Mike Conley
The McDowell News
Fri, 02 Nov 2007 14:17 EDT
Nearly a century ago, a tremendous explosion rocked the remote forests of Siberia. To this day, the weird event is considered to be one of the world's greatest unsolved mysteries.
On the morning of June 30, 1908, a massive explosion occurred in the air above the remote, isolated forests near the Stony Tunguska River in Siberia, Russia. For that reason, it is often called the Tunguska event.
The blast was estimated to be between 10 and 20 megatons of TNT -- 1,000 times more powerful than the atomic bombs dropped on Hiroshima and Nagasaki in 1945. The explosion felled an estimated 80 million trees over an area of 830 square miles. The shock wave is estimated to have measured 5.0 on the Richter scale, according to a Web site.
One eyewitness who lived about 40 miles south of the explosion described the sky being "split in two" and fire appearing high and wide over the vast forest.
"At that moment, I became so hot that I couldn't bear it, as if my shirt was on fire; from the northern side, where the fire was, came strong heat," the witness said. "I wanted to tear off my shirt and throw it down, but then the sky shut closed, and a strong thump sounded, and I was thrown a few yards. I lost my senses for a moment, but then my wife ran out and led me to the house.
"After that such noise came, as if rocks were falling or cannons were firing, the earth shook, and when I was on the ground, I pressed my head down, fearing rocks would smash it. When the sky opened up, hot wind raced between the houses, like from cannons, which left traces in the ground like pathways, and it damaged some crops. Later we saw that many windows were shattered, and in the barn a part of the iron lock snapped."
That account is only one of many from the Siberian villagers who were around to experience the enormous blast. Some of them were convinced that the explosion signaled the end of the world and the final judgment. It is fortunate that the explosion happened in a remote, unpopulated area. If it had occurred over a major city, there is no doubt that the city would have been utterly destroyed and millions of people killed.
But how could such an explosion happen 37 years before the invention of the atomic bomb?
Because the Tunguska region was so isolated, the first recorded expedition to the site didn't happen until the 1920s. Russian scientist Leonid Kulik first journeyed to the site in 1921 and spoke to local people who saw and felt the blast. He deduced that the explosion had been caused by a giant meteorite impact. He persuaded the Soviet government to fund an expedition to the Tunguska region.
Kulik's party finally reached the site in 1927. To their surprise, no crater was to be found. Instead, a vast region of downed trees was found stretching about 30 miles across. Later expeditions would further explore the region devastated by the blast. It is interesting to note that no elevated levels of radiation, which are typical of nuclear explosions, have been found at the site.
Today many scientists believe that the Tunguska event was caused by a meteor or comet which blew up just prior to hitting the Earth's surface. It is often used as an example of what could happen if a meteor or comet were to hit the Earth today, especially over a large metropolitan area.
But others are not sure about that explanation. Some believe that the Tunguska event was caused by the explosion of an alien spaceship. In 1998, a TV show on Turner Network Television referred to the Tunguska event as the "Russian Roswell" and claimed that UFO debris has been recovered from the site. In 2004, a group of Russian UFO enthusiasts claimed to have found the wreck of an alien spacecraft at the blast site.
So today, the Tunguska event remains as one of the strangest episodes in history. And we can only pray that something like that doesn't happen over a populated area.
Contact Mike Conley at 652-3313, ext. 3422 or e-mail nconley@mcdowellnews.com
Richard L. Hill
The Oregonian
Thu, 01 Nov 2007 05:51 EDT
Overhunting. Abrupt climate change. Disease.
Scientists have cited those and other theories in their decades-old debate about why mammoths, mastodons, sloths, saber-toothed cats, camels, horses and other large creatures disappeared from North America at the end of the last ice age.
The researchers say the impact also may have wiped out or fragmented the prehistoric Clovis people who flourished in North America at the time.
UO archaeologists Douglas Kennett and Jon Erlandson are among about two dozen scientists who say the impact also could have led to the abrupt cooling known as the Younger Dryas, which lasted 1,200 years.
"I initially thought this idea for a comet impact was preposterous," Erlandson said. "But as I started reviewing the data from multiple locations, the concept began to capture my imagination. There was dramatic change going on at that time. A comet contributing to that change is just a hypothesis at this point, and it's probably going to take at least 10 more years of research to figure out if that occurred."
The researchers laid out their proposed theory recently in the Proceedings of the National Academy of Sciences. They say the evidence is in a 2-inch-thick carbon-rich black mat found in about 50 sites across North America.
Their article says the layer contains grains with iridium, carbon spherules and fullerenes packed with concentrations of helium 3 -- "all of which are evidence for an extraterrestrial impact" about 12,900 years ago and the raging wildfires that followed.
The scientists studied samples of black mats from 10 Clovis archaeological sites in Canada, California, Arizona and South Carolina. Evidence of mammoths and other animals and early human hunters are found beneath the black mat but are missing within or above the strip.
They suggest that heat from the detonation or impact may have set off wildfires across the continent and destabilized the vast Laurentide Ice Sheet that covered much of Canada and the northern United States. The melting of ice may have led to a flood of fresh water, changing ocean currents in the North Atlantic and contributing to the cooling climate that reduced human populations and added to the demise of the animals.
No giant crater has been found from the impact, but the scientists say the comet may have broken into smaller pieces and detonated in various places.
"If a comet hit the Laurentide Ice Sheet, it would not have left a big crater," Erlandson said. "It's ice on ice, and it's going to throw up enormous amounts of shattered ice and debris."
Geological features known as Carolina Bays -- hundreds of thousands of small depressions from New Jersey to Florida -- may have been caused by the disintegrating object. Samples from 15 of the depressions contained the iridium-rich magnetic grains and carbon spherules.
The elliptical depressions are oriented in a northwest-southeast direction that point toward Canada and the Great Lakes, suggesting the object disintegrated in that area.
"The initial impact would have been very heavy in eastern North America, and western North America would have been more of a refuge," Erlandson said. "Some of the initial modeling of this impact indicated that it would have created an enormous rolling fireball and force wave that engulfed the entire continent and wiped out everything. Archaeology tells us that it didn't do that; there were animals and people that survived."
Erlandson said the reduced populations of large animals in the West probably would have been under tremendous pressure from changes in the environment and from hunting by remnants of Clovis populations.
The tell-tale black mats have not been found in the Northwest, Kennett said, but scientists "have some leads on sites to visit and sample." They include a site near Mill Creek in Woodburn's Legion Park, where a treasure trove of remains from extinct ice age mammals has been uncovered in recent years.
His father, James Kennett, a paleoceanographer at the University of California at Santa Barbara, introduced the impact idea with Richard Firestone of the Lawrence Berkeley National Laboratory and Allen West, an Arizona researcher.
Douglas Kennett is in Spain looking for potential effects of the impact in Europe and soon will look at sites in the Netherlands.
One of the archaeological sites being investigated is about 30 miles off the Southern California coast on Daisy Island, where Erlandson has uncovered evidence that humans used the islands about 13,000 years ago. Erlandson plans to return to the island with other researchers to determine whether there's additional evidence that would support the comet impact concept.
Idea has its critics
The new hypothesis already has drawn critics.
"I think we would all like to see a smoking gun," said Alison Stenger, a Portland archaeologist who has led excavations in Woodburn and McMinnville that have turned up ice age animals. "We have not seen any evidence of a black mat at these sites, and we've examined a lot of sediment."
Not all large animals died off at the end of the ice age, and many "were alive and well" at Woodburn and Rancho La Brea tar pits in Los Angeles nearly 2,000 years after the proposed impact.
"I'm convinced that a group of things led to the extinction of these animals," she said. "A comet certainly would be tidy explanation, but I'm not seeing the physical evidence that this occurred."
Donald Grayson, a University of Washington anthropology professor who has studied the animal extinctions, also is skeptical.
Grayson said there are other explanations for the black mats, which "are most assuredly not an indicator of an impact event." There's no evidence of massive burning at the end of the last ice age, he said, and there's no evidence suggesting that "post-Clovis human densities in North America were less than Clovis ones."
Comment: This is clearly untrue, given the evidence presented in the article:
In the 1990s, W. Topping (14) discovered magnetic microspherules and other possible ET evidence in sediment at the Gainey PaleoAmerican site in Michigan (see also ref. 15), and Lougheed (16) and Bi (17) reported that late Pleistocene glacial drift contained similar cosmic spherules. We now report substantial additional data from multiple, well dated stratigraphic sections across North America supporting a major ET airburst or collision near 12.9 ka. Directly beneath the black mat, where present, we found a thin, sedimentary layer (usually 5 cm) containing high concentrations of magnetic microspherules and grains, nanodiamonds, iridium (Ir) at above background levels, and fullerenes containing ET helium. These indicators are associated with charcoal, soot, carbon spherules, and glass-like carbon, all of which suggest intense wildfires. Most of these markers are associated with previously recorded impacts, but a few are atypical of impact events. We identify this layer as the YD boundary (YDB), and we refer to this incident as the YD event.
...
Ten Clovis and equivalent-age sites were selected because of their long-established archeological and paleontological significance, and, hence, most are well documented and dated by previous researchers (see SI Table 2). Two are type-sites where unique PaleoAmerican projectile point styles were first named: the Clovis-point style at Blackwater Draw, NM, and the Gainey-point style at Gainey, MI. Three of the sites are confirmed megafaunal kill sites, and six of 10 have a black mat overlying the YDB. At Blackwater Draw and Murray Springs, the YDB is found directly beneath the black mat and overlying Clovis artifacts with extinct megafaunal remains.
The other sample sites were in and around 15 Carolina Bays, a group of 500,000 elliptical lakes, wetlands, and depressions that are up to10 km long and located on the Atlantic Coastal Plain (SI Fig. 7). We sampled these sites because Melton, Schriever (20), and Prouty (21) proposed linking them to an ET impact in northern North America. However, some Bay dates are reported to be 38 ka (22), older than the proposed date for the YD event.
©PNAS Fig. 7. Aerial photo (U.S. Geological Survey) of a cluster of elliptical and often overlapping Carolina Bays with raised rims in Bladen County, North Carolina. The Bays have been contrast-enhanced and selectively darkened for greater clarity. The largest Bays are several kilometers in length, and the overlapping cluster of them in the center is ≈8 km long. Previous researchers have proposed that the Bays are impact-related features.
It's interesting to note that the 38 Ka dates of some of the Carolina Bays correspond to two 19,000 year precessional periods.
The skepticism is natural "given the magnitude of this hypothesis and its potential significance in the history of our planet," and more research is needed, Douglas Kennett said. "The scale of the inquiry is also massive, and we have just started to scratch the surface "
Richard L. Hill: 503-221-8238; richardhill@news.oregonian.com
Comment: The fact that large scale cometary impacts have happened so relatively recently, and seem to happen in cycles, and are getting so much attention lately, makes one wonder if Something Wicked This Way Comes.
Right now, NASA is tracking 127 asteroids that have a very small chance of striking the planet. That number is about to get a lot higher. Stronger telescopes, and a new mandate from Congress, will allow scientists to detect thousands of smaller asteroids more likely to hit Earth. And scientists are plotting ways to stop them, from "gravity tractors" to solar ray guns. "There is no question that these will hit the Earth," says Russell Schweickart, a former Apollo astronaut who is involved in a group studying asteroids. "The question is how often we will have to do something about it." In fact, Schweickart thinks world leaders might have to do something about it very soon, within the next 15 years.
Stronger telescopes or more asteroids and comets?
And what would cause these cycles?
Cometary evidence of a massive body in the outer Oort cloud
Approximately 25% of the 82 new class I Oort cloud comets have an anomalous distribution of orbital elements that can best be understood if there exists a bound perturber in the outer Oort cloud. Statistically significant correlated anomalies include aphelia directions, energies, perihelion distances and signatures of the angular momentum change due to the Galaxy. The perturber, acting in concert with the galactic tide, causes these comets to enter the loss cylinder - an interval of Oort cloud comet perihelion distances in the planetary region which is emptied by interactions with Saturn and Jupiter. More concisely, the impulse serves to smear the loss cylinder boundary inward along the track of the perturber. Thus it is easier for the galactic tide to make these comets observable. A smaller number of comets are directly injected by the impulsive mechanism. We estimate that the perturber-comet interactions take place at a mean istance of 25000 AU. The putative brown dwarf would have a mass of 3 +/- 2M Jupiter and an orbit whose normal direction is within 5 degrees of the galactic midplane. This object would not have been detected in the IRAS database, but will be detectable in the next generation of planet/brown dwarf searches, including SIRTF. It is also possible that its radio emissions would make it distinguishable in sensitive radio telescopes such as the VLA.
Jon Nance
The Springfield News-Leader
Thu, 01 Nov 2007 09:20 EDT
The first literate humans, living in Mesopotamian cities like Ur and Erech more than 5,000 years ago, seemed to believe that comets caused bad things to happen or, at the very least, they foretold that bad things would happen. Either way, they regarded a new comet in the evening sky as a portent of some future disaster.
If they were right, then the time has come for us to don sackcloth and ashes, because a new comet appeared last week in the constellation Perseus.
Well, almost.
The "new" comet turns out to be a familiar one with a period of 6.9 years, now about 100 million miles from Earth. It was discovered by British amateur astronomer Edwin Holmes in 1896 and, according to custom, given his name.
Comet Holmes was, until last week, a tiny ball of dusty ice only a couple of miles in diameter, held together by electrochemical forces as much as by gravity. Its gritty surface reflected just enough sunlight to make it shine at 17th magnitude, far beyond the reach of unaided human eyes. It then brightened abruptly to magnitude 2.5 and became the third-brightest object in Perseus, brighter than all but two of the constellation's stars.
It remains about that bright as I write this.
It is clearly visible even to my feeble eyes and is a rather large and quite unstarlike fuzzy blob when viewed with binoculars.
Try finding it about 7:40 tonight. It will be about halfway down from the "W"-shaped asterism of Cassiopeia to the northeastern horizon and a little to the left of Mirfak, Perseus' brightest star. If you have trouble using this description, try consulting the finder chart at the Web site of Sky and Telescope Magazine, www.skyandtelescope.com.
How did comet Holmes manage to increase its brightness almost a millionfold in only a few days? Some kind of explosion seems to have blown a large quantity of dust and grit from its surface out into the surrounding space.
Moving outward at more than 1,000 miles per hour, this dust now occupies a volume nearly equal to that of the sun.
But what caused the explosion? Not many astronomers seem willing
even to guess about that in print right now. So we can be pretty sure
that no one knows.
Jon Nance is professor emeritus at Missouri State University.
Glenn K. Roberts
The Guardian
Thu, 01 Nov 2007 15:44 EDT
Though the nights are definitely chillier now, there's much to see in the night sky worth getting out for, especially this month.
Dress warmly and head for a dark site away from city lights and enjoy the special treats on display for those with the fortitude to venture forth.
The show starts just after sunset, with Jupiter shining brightly low in the southwest sky. You'll have to be quick to spot Jupiter's four largest moons - Io, Europa, Callisto and Ganymede - as Jupiter will follow the sun below the horizon soon after darkness falls. On Nov. 12, look for the slender, three-day old crescent moon just to the lower left of Jupiter.
Mars is preparing for its best showing in the past two years next month by nearly doubling in brightness and increasing significantly in apparent size in November. Mars is heading towards opposition in December, when it will be at its brightest and peak visibility.
It begins November in a slightly gibbous phase, but by month's end, its disk will be nearly full. Look for Mars rising in the east about three hours after sunset in the constellation of Gemini - the Twins. If you have a telescope, begin observing just before midnight, watching for subtle dark and bright markings. Make a note of your observations, perhaps even making a coloured sketch, so that you can compare your observations with those in December.
As November opens, Saturn struts onto the night's celestial stage in the east around 2 a.m. By month's end, it will rise shortly before midnight. Always a spectacular sight in a telescope, Saturn's ring system is worth looking for. If your telescope is a decent size and has good optics, you might catch a glimpse of Saturn's brightest moon - Titan - north of the planet on Nov. 3 and 19, and south of the planet on Nov. 11 and 27.
Bright Venus returns to the early morning sky this month, rising an hour and a half after Saturn appears above the eastern horizon and four hours before the sun. An excellent photo opportunity is in the pre-dawn sky of Nov. 4, when the crescent moon sits between Saturn and Venus. The next morning, the moon will sit to the right of Venus.
Mercury makes its best showing of the year this month, reaching its highest point in the east-southeast sky (approximately a hand's width at arm's length) about 45 minutes before sunrise on Nov. 8. The solar system's innermost planet rises about 90 minutes before the sun.
On Nov. 7, look for the crescent moon to the right of Mercury, with bright Spica (the brightest star in the constellation of Virgo - the Maiden) just below. If you've never seen Mercury, try and see it this month as by month's end it disappears from view.
The second of the year's two premiere meteors showers - the Leonids (radiant in Leo - the Lion) - arrives this month, peaking in the pre-dawn sky of Nov. 18. Although it is expected that the peak, which arrives about 3 a.m. on Nov. 18 when the Leo is high in the eastern sky, will generate 20-40 meteors/hour, in the Maritimes we may be treated to increased numbers of meteors just before midnight on Nov. 17 when Earth crosses the orbital node of the Leonids' parent comet, Temple-Tuttle. Dress warmly, get comfortable with a chair or lots of blankets, get out early and get ready for the show. It just might be one of those rare times when we will be treated to a meteor storm.
In the hours just preceding dawn, when the Leonids strike Earth's atmosphere almost head on, expect to see some very bright meteors and perhaps even some fireballs, streaking across the sky.
Even as the stars fade and the eastern horizon starts to glow, keep watching, as fireballs can easily be seen through the twilight.
Two comets can be found in the November night sky. Soon after the sun has set and twilight deepens, use binoculars or a telescope to scan just above the southwest horizon. Comet LONEOS should be visible just above the horizon, with its tail angling up towards Jupiter. A decent telescope should show the comet's two tails - the bright, yellowish, dust tail curving towards the north and the duller, bluish, ion tail streaking straight out from the comet's southeastern flank. Be quick to see this visitor to the solar system as after the first week of November, the comet will be all but impossible to see in binoculars or small telescopes.
The other comet now in the sky is something of a pleasant surprise. Just last week, in the latter days of October, Comet Holmes (discovered in 1892 by British astronomer, Edwin Holmes) suddenly blossomed from an extremely faint comet (visible in only the largest of telescopes) to naked-eye visibility, a million-fold increase in brightness. It now sits in the constellation of Perseus - the Warrior Prince in the northeast sky as darkness falls. It is clearly visible to the naked-eye as a bright, fuzzy ball which, as has just been reported, has swollen in size to an object larger than Jupiter (at an equal distance). Go to SpaceWeather.com for more information, pictures and a sky chart on this amazing comet and get outside the first clear night available and have a look at Comet Holmes.
Until next month, clear skies and good hunting.
Events (ADT):
Nov. 1 - Last quarter moon; 6:18 p.m.
Nov. 9 - Moon at apogee (farthest from Earth; 404,310 kms); 8:32 a.m.
Nov. 9 - New Moon; 7:03 p.m.
Nov. 17 - First Quarter Moon; 6:33 p.m.
Nov. 17 - Leonid meteor shower (start looking before midnight)
18 - Leonid meteor shower peak (around 3 a.m.)
Nov. 23 - Moon at perigee (closest to Earth; 355,120 kms); 8:13 p.m.
Nov. 24 - Full moon; 10:30 a.m.
Glenn K. Roberts, a member of the Charlottetown Astronomy Club, writes for The Guardian the first Thursday of the month. To comment on his column e-mail him at groberts @isn.net.
BBC News
Fri, 02 Nov 2007 15:51 EDT
A Devon astronomer was able to track the unexpected brightness of a comet with a telescope in the Canary Islands.
 |
| ©n/a |
| The earth in relation to the comet is 244 million km (151 614 570 miles) away |
Professor Tim Naylor from Exeter University saw Holmes Comet using the Isaac Newton Telescope at La Palma.
Professor Naylor said: "Comets are not normally my thing, so it was a challenge to observe something so bright with a large telescope."
The comet has brightened by a factor of a million and can now be seen across the UK with the naked eye.
Fuzzy object
On Monday the comet was a very faint object that needed a large telescope to see it, then on Tuesday night, Professor Naylor saw it suddenly become much brighter.
The comet is seen as a small fuzzy object as bright as a medium-brightness star in the constellation Perseus and can be viewed for the next few weeks.
Back in Exeter the professor said: "I walk out in to my back garden and my eight year old can see it.
"The best time is early evening before the moon comes up."
Astronomers believe a build-up of gas under part of the surface has ruptured it making it appear brighter but they are still studying it to find out the cause.
Dawn Stover
popsci.com
Tue, 30 Oct 2007 18:02 EDT
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| ©Nick Kaloterakis |
| On the Rocks: Deep-space travelers arrive at their destination. Lack of gravity could make exploring the asteroid tricky. |
A manned mission to an asteroid sounds far-fetched, but a new study says it will soon be possible. The goal?: "to significantly alter the orbit of an asteroid, in a controlled manner, by 2015."
Here we are, nearly eight years into the 21st century, and the most spectacular manned mission NASA can pull off is a trip to the International Space Station, a mere 210 miles above the Earth. Even the most ambitious part of NASA's current plans for human spaceflight involves visiting a celestial body we've already been to: the moon. Astronauts, space buffs and an unimpressed public hunger for space exploration that's more dramatic, more heroic, more new. Something like, say, landing astronauts on a distant rock hurtling through space at 15 miles per second.
That's exactly the kind of trip NASA has been studying. In fact, scientists at the space agency recently determined that a manned mission to a near-Earth asteroid would be possible using technology being developed today. The mission wouldn't be easy. A crew of two or three would spend months riding in a cramped spacecraft before reaching their barren, nearly gravity-free target. That such a mission is even being considered, though, says a lot about the versatility of NASA's next fleet of spacecraft and the ambitions the agency has for them. If nothing else, it's a signal that space exploration could soon get much more exciting.
The Allure of an Asteroid
This wouldn't be our first trip to an asteroid. We've been visiting them by proxy for years now, using unmanned space probes. In 2000 NASA's NEAR Shoemaker spacecraft arrived at 433 Eros, which a century earlier became the first near-Earth asteroid known to man; five years later, the Japanese Hayabusa probe touched down on asteroid 25143 Itokawa.
Yet unmanned probes have their limitations. NEAR Shoemaker and Hayabusa gathered a good deal of data, but we still don't know the exact composition and internal structure of the asteroids they visited. And although Hayabusa was designed to collect two small samples from Itokawa, it's doubtful the probe will actually have anything onboard when it returns in 2010.
Humans, however, could be much more effective. Unlike robots, we adapt to our environment in real time. "We spend weeks at a rock with a Mars rover, trying to determine what it is," says Rob Landis, an engineer at NASA's Johnson Space Center and one of the co-leaders of the mission feasibility study. "An astronaut could make that determination in a matter of seconds."
A human crew could travel across an asteroid more intelligently than a robot, making it easier to deploy scientific instruments, collect samples, and zero in on the areas of greatest interest. "No doubt, on a human mission we would characterize an asteroid better than we ever have," says Bruce Betts, director of projects for the Planetary Society.
Plenty of characterization needs to be done. While most asteroids are a safe distance from Earth (in an approximately 190-million-mile-wide expanse between Mars and Jupiter), Jupiter's gravitational tug and, less often, collisions between asteroids can kick these objects into orbits that pass uncomfortably close to Earth. The 270-meter-wide asteroid 99942 Apophis, for example, will pass within roughly 24,000 miles of Earth in 2029, and could come back for a direct hit in 2036.
And if we're to have any hope of deflecting asteroids, we need to know a lot more about them than we do now. First off: What, exactly, are they made of? Measurements taken by Hayabusa indicate that 40 percent of Itokawa's volume is empty space. If some asteroids are truly this porous, that's helpful information for any plan to destroy or deflect an Earth-bound object.
Averting the apocalypse isn't the only reason to study near-Earth asteroids, though. They could be floating gold mines for future deep-space expeditions. Preliminary observations suggest that some asteroids are rich in useful minerals and, better yet, frozen water - the most valuable resource a space traveler could hope to find. If water could be extracted from asteroids, it could not only be used for drinking, but also broken down into oxygen for breathing and hydrogen for rocket fuel. "It might be an ultimate way to get to Mars," Landis says.
Far beyond the Moon
Forty-one years ago, a scientist at Northrop (now Northrop Grumman) proposed using moon rockets to go to an asteroid. In some ways, NASA's latest plan is similar; it too relies on spacecraft designed for lunar travel - the vehicles belonging to the Constellation program, which NASA is building to replace the shuttle and then go to the moon and beyond.
But although the hardware is similar, an asteroid mission couldn't be more different from a trip to the moon. Actually, an asteroid mission has one clear advantage: The virtually negligible gravity at the crew's destination means they need less fuel to get home.
That lack of gravity, however, means that the first person to reach an asteroid will not take one giant leap for mankind, and he will not drive a dune buggy. "You're going to be wearing a backpack and flying around," says Rusty Schweickart, an Apollo 9 astronaut who is now chairman of the B612 Foundation, whose goal is "to significantly alter the orbit of an asteroid, in a controlled manner, by 2015." Astronauts might explore the asteroid from inside their spacecraft using remotely controlled instruments, or they might anchor their spacecraft to the surface of the asteroid by firing hooks into the object and reeling themselves in.
The biggest logistical hurdle is the sheer distance involved. It takes a few days to travel the 238,855 miles to the moon, but it will take more than a month to cover the distance of up to 4.5 million miles separating us from just about any asteroid of interest. The crew of two or three will live in their small quarters for several months. Psychological experiments and historical precedent show that isolation and boredom can mentally break an otherwise sane person; NASA will have to find a way to keep an asteroid-bound crew from losing their minds. It will also have to engineer a means to shelter the astronauts from the intense cosmic radiation found outside the protection of Earth's magnetic field.
Most ominously, though, there's this little wrinkle: If anything goes wrong out there for an asteroid-bound space traveler, there's almost no chance of rescue.
Destination: Unknown
Which asteroids would we visit? "You need an asteroid that's in an orbit very similar to the orbit of the Earth," says David Morrison, a senior scientist at the NASA Astrobiology Institute. "There aren't many, so we would be quite dependent on carrying out a new survey." The ideal target asteroid will also be at least a couple hundred meters in diameter, will have a very slow rotation of 10 hours or more, and will have the potential to come too close to Earth for comfort. Scientists suspect approximately 1,000 asteroids meet these criteria - but we have yet to find them.
In 2005, Congress ordered NASA to develop a program to detect, track, catalog, and characterize, by the end of 2020, 90 percent of all near-Earth objects (an expanded category that includes comets as well as asteroids) 140 meters in diameter and larger. The hitch: Right now, NASA doesn't have the budget to get it done by that deadline.
The interplay between Congress and NASA brings up the more terrestrial matter of politics. The stated goal of President George Bush's administration is to launch an "extended" moon mission by 2020 and, later, to build a permanent moon base that could function as a springboard for a manned mission to Mars. That could all change after next year's election, however. A new administration could divert money from human space exploration to any number of other projects - say, satellite-based climate science. "I don't think that the Vision" - the Bush administration's plan for a new era of human space exploration - "as written today is likely to survive the election, even if a Republican is elected," says Robert Zubrin, president of the Mars Society.
Then again, some experts believe the Constellation program will move forward no matter who wins in '08; if it doesn't, NASA won't have any spacecraft after the shuttle retires. And although the feasibility study doesn't mean we're headed to an asteroid soon, it does tell us that if we decide to go, we can get there. So if, say, we find one day that we need to visit 99942 Apophis to find the best way to knock it off a collision course with Earth, or if we need a refueling station for astronauts headed for Mars, we might be in luck.
Comment: To add another possibility for NASA's growing interest in near earth asteroids, be sure to see the SOTT Focus Feature: Something Wicked This Way Comes
Associated Press
Mon, 05 Nov 2007 20:43 EST
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| ©Unknown |
| Comet Holmes is seen among the stars of the constellation Perseus in the North-Eastern sky.
|
KNOXVILLE, Tenn. - A comet that unexpectedly brightened in the last couple of weeks and is now visible to the naked eye is attracting professional and amateur interest.
Paul Lewis, director of astronomy outreach at the University of Tennessee, is drawing students to the roof of the Nielsen Physics Building for special viewings of Comet 17P/Holmes.
The comet is exploding and its coma, a cloud of gas and dust illuminated by the sun, has grown to be bigger than the planet Jupiter. The comet lacks the tail usually associated with such celestial bodies but can be seen in the northern sky, in the constellation Perseus, as a fuzzy spot of light about as bright as the stars in the Big Dipper.
"This is truly a celestial surprise," Lewis said. "Absolutely amazing."
Until Oct. 23, the comet had been visible to modern astronomers only with a telescope, but that night it suddenly erupted and expanded.
A similar burst in 1892 led to the comet's discovery by Edwin Holmes.
"This is a once-in-a-lifetime event to witness, along the lines of when Comet Shoemaker-Levy 9 smashed into Jupiter back in 1994," Lewis said.
Scientists speculate the comet has exploded because there are sinkholes in its nucleus, giving it a honeycomb-like structure. The collapse exposed comet ice to the sun, which transformed the ice into gas.
"What comets do when they are near the sun is very unpredictable," Lewis said. "We expect to see a coma cloud and a tail, but this is more like an explosion, and we are seeing the bubble of gas and dust as it expands away from the center of the blast."
Experts aren't sure how long the comet's show will last but estimate it could be weeks if not months. Using a telescope or binoculars help bring the comet's details into view, they said.
New Scientist
Tue, 06 Nov 2007 11:13 EST
Comet 17P/Holmes has certainly given sky-watchers - backyard and professional astronomers alike - a thrilling chance to see a cometary outburst on a grand scale. After we posted my story about on-going speculation about what could have caused this outburst (and the one 115 years ago), many readers posted comments related to two questions: Could this have been triggered by a collision with an object in the main asteroid belt? And why can't we see more of a tail on this comet?
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| ©Pic du Midi Observatory/Francois Colas/Jean Lecacheux/Boris Baillard |
| Holmes |
Here's what I found out: Michael Mumma at the Goddard Center for Astrobiology says such a collision in the asteroid belt is theoretically conceivable. He noted that comet guru Fred Whipple suggested that a collision with a small asteroid could have provided the right amount of energy to produce the ejecta and brightening observed in the comet's 1892 flare-up.
But Mumma himself thinks it would be "very surprising" if a collision were the cause of the outburst. He says part of the difficulty in weighing this possibility is that it's very hard to estimate how many small boulders are in the asteroid belt. These tiny objects - on the order of one-metre across - are beyond the detection limits of telescopes.
Brian Marsden, former director of the International Astronomical Union's Minor Planet Center, says plainly that he doesn't believe this to be a viable explanation for the outburst. He says it's hard to believe that this comet, among all those that pass through the asteroid belt, has been struck twice by objects in the belt - once in 1892 and again this year.
Many people have been discussing whether or not this comet has a tail. Comets typically have two types of tail - a dust tail and an ion tail. The dust tail is made of fine dust from the comet's main body, or nucleus, that has been swept out by the Sun's radiation. It usually points in the direction from which the comet came. The ion tail is caused by the Sun's magnetic field sweeping ions (which start out as neutral gas particles on the body of the comet) into a line that always points directly away from the Sun.
Marsden says the there isn't much of either type of tail. He says it's possible that there just isn't enough very fine dust in the material coming off the nucleus to be pushed by sunlight into a nice dust tail. (He says there may only be "fairly hefty dust" in the comet's coma.)
Some people have argued that we can't see the comet's ion tail because the orientation of the Sun, Earth and comet means the tail is mostly pointing away from Earth.
But though the tail does look fore-shortened, Mumma says the accumulated surface brightness would be greater seen from one end than if it were seen spread out, from the side. He likened it to looking at the contrail of a plane. If we saw the stream from the side, we would basically see right through it. But if we were in front of or behind the contrail, looking into it, it would appear many times brighter.
Marsden says the comet is so far from the Sun that the solar wind is not interacting strongly enough with the ionised gas to produce a fantastic ion tail. But he says it doesn't bother him that it doesn't have much of a tail. After all, the "fuzzy head" is putting on such a great show of its own.
Kimm Groshong, contributor
Maria Cristina Valsecchi
National Geographic
Thu, 08 Nov 2007 06:06 EST
Almost a century after a mysterious explosion in Russia flattened a huge swath of Siberian forest, scientists have found what they believe is a crater made by the cosmic object that made the blast.
The crater was discovered under a lake near the Podkamennaya Tunguska River in western Siberia, where the cataclysm, known as the Tunguska event, took place.
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| ©www-th.bo.infn.it/tunguska / University of Bologna |
| A three-dimensional rendering of Lake Cheko in Tunguska, Siberia. The level of the lake is lowered 40 meters (131 feet) to emphasize its cone-like shape. |
On June 30, 1908, a ball of fire exploded about 6 miles (10 kilometers) above the ground in the sparsely populated region, scientists say. The blast released 15 megatons of energy - about a thousand times that of the atomic bomb dropped on Hiroshima - and flattened 770 square miles (2,000 square kilometers) of forest.
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| ©unk |
| The Tunguska event devastated parts of Siberia in 1908 |
Since then many teams of scientists have combed the site, but none was able to find any fragments of an object, like a rocky asteroid or a comet, that might have caused the event.
In their new study, a team of Italian scientists used acoustic imagery to investigate the bottom of Lake Cheko, about five miles (eight kilometers) north of the explosion's suspected epicenter.
"When our expedition [was at] Tunguska, we didn't have a clue that Lake Cheko might fill a crater," said Luca Gasperini, a geologist with the Marine Science Institute in Bologna who led the study.
"We searched its bottom looking for extraterrestrial particles trapped in the mud. We mapped the basin and took samples. As we examined the data, we couldn't believe what they were suggesting.
"The funnel-like shape of the basin and samples from its sedimentary
deposits suggest that the lake fills an impact crater," Gasperini said.
A "Soft Crash"
The basin of Lake Cheko is not circular, deep, and steep like a typical impact crater, the scientists say.
Instead it's elongated and shallow, about 1,640 feet (500 meters) long with a maximum depth of only 165 feet (50 meters).
It also lacks the rim of debris usually found around typical impact craters, such as the Meteor Crater in Arizona.
Gasperini's team says that the basin's unusual shape is the result of a fragment thrown from the Tunguska explosion that plowed into the ground, leaving a long, trenchlike depression.
"We suggest that a 10-meter-wide [33-foot-wide] fragment of the object escaped the explosion and kept going in the same direction. It was relatively slow, about 1 kilometer a second [0.6 mile a second]," Gasperini said.
The lake is located along the most probable track of the cosmic body, he added, which likely made a "soft crash" in the marshy terrain.
"It splashed on the soft, swampy soil and melted the underlying permafrost layer, releasing CO2 [carbon dioxide], water vapor, and methane that broadened the hole, hence the shape and size of the basin, unusual for an impact crater.
"Our hypothesis is the only one that accounts for the funnel-like morphology of Lake Cheko's bottom," he added.
In a previous expedition, Russian scientists studied Lake Cheko and concluded that it had formed before 1908, indicating that it was not formed by the Tunguska event.
The team had measured sediments on the bottom of the lake and determined that the deposits were accumulating there at about 0.4 inch (1 centimeter) a year. This suggested that Lake Cheko was several centuries old.
But Gasperini's team argues that the older deposits found by the Russians were already there when the explosion took place.
"We found evidence that only the topmost, one-meter-deep [three-foot-deep] layer of debris actually came from the inflowing river," Gasperini said.
"[The] deeper sediments are deposits that predate 1908. They were the target over which the impact took place, so Lake Cheko is only one century old."
The team's findings are based on a 1999 expedition to Tunguska and appeared in the August issue of the journal Terra Nova.
Asteroid or Comet?
William Hartmann, senior scientist of the Planetary Science Institute in Tucson, Arizona, said the new findings are compelling but do not address all of the lingering questions about the event.
"It's an exciting result that might shed new light on the Tunguska explosion," he said. "Certainly it warrants new studies of the area.
"But it raises a question in my mind: If one large fragment hit the ground, we would normally expect thousands of smaller fragments also to hit the ground along the path, and many searches have failed to find such meteorite fragments. So, why no smaller pieces?"
Finding fragments from the explosion is considered key to determining what kind of object made the impact. An asteroid would probably leave some remains, while a comet might be annihilated in the blast, Hartmann said.
"Our crater hypothesis is consistent with both possibilities," Gasperini said.
"If the body was an asteroid, a surviving fragment may be buried beneath the lake. If it was a comet, its chemical signature should be found in the deepest layers of sediments."
Gasperini and his colleagues are planning to go back to Siberia next year to search for more, and perhaps more conclusive, clues to the century-old puzzle.
"We want to dig deeply in the bottom of the lake to definitively test our hypothesis and try to solve the Tunguska mystery," he stated.
Curtis Roelle
carrollcountytimes.com
Sat, 10 Nov 2007 00:34 EST
November's annual Leonid meteor shower is associated with debris left behind during passages of Comet 55P/Tempel-Tuttle. Although this year's shower is expected to be unremarkable, there is a chance that short-lived outbursts could occur.
The 2007 shower may be unremarkable but it is notable for several reasons. First, it is expected to peak on a weekend night, making it easier for observers who like staying up late. The nominal predicted peak should occur on the night of Nov. 17 to Nov. 18.
Second, the moon gets out of the way before things get going. According to Sky & Telescope magazine, the best viewing "starts around midnight, when Leo rises." In Westminster, the moon cooperates, setting at 12:53 Sunday morning. The magazine says you will "likely see the most meteors 2-3 hours before sunrise."
The best way to increase the number of meteors you can expect to see during any shower is to observe from a dark sky site far away from interference from artificial outdoor lighting. This means traveling away from any nearby cities. The darker the sky is at your observing site the more meteors you will see.
Third, depending on which model you subscribe to, one or more outbursts may happen in which the expected hourly meteor rate spikes briefly. In his "Astronomical Calendar 2007," Guy Ottewell writes of a predicted outburst with a "zenithal hourly rate" (ZHR) of up to 200 meteors per hour between 11 p.m. Saturday and midnight.
Another outburst prediction is based on a model derived by Esko Lyytinen and Tom van Flandern. It was used to successfully predict an outburst in the 2006 Leonid shower. In a recent e-mail message to StarPoints, Mr. Lyytinen of Finland noted that he expects this outburst "to be quite weak" consisting primarily of "faint meteors" and fewer in number than last year's modest outburst of "only a few dozens" of meteors.
The underlying cause is that the Earth is expected to travel through debris left by Tempel-Tuttle during its 1932 passage. Unfortunately, this outburst is predicted to occur around 6 p.m. Nov. 18. Thus it won't be well suited for viewing from the United States.
Another outburst prediction by Russian Mikhail Maslov is based on a modified version of the Lyytinen-van Flandern model. It expects the surge to have a ZHR up to 60 to 65 meteors per hour.
The ZHR is an idealized rate with a technical meaning. It is the number of meteors that may be expected in one hour if the "radiant" - the point in the sky from which all meteors in a given shower appear to emanate from - was located at the observer's zenith (straight overhead) and viewed from a dark sky site free from light pollution. Of course, the radiant won't be that high in the sky, so the actual rate will be lower.
SpaceWeather.com
Sat, 10 Nov 2007 00:40 EST
"Is Comet 17P/Holmes losing its tail?" asks Italian astronomer Paolo Berardi. "Last night I recorded an image showing a big disconnection event that was not present on Nov 8th."
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| ©Paolo Berardi |
Jack Newton of the Arizona Sky Village saw it, too. "The comet has a huge eruption moving along its tail. Holmes is more bizarre with each passing day."
This event does not necessarily signal a new outburst of Comet Holmes. Comet tails can be disconnected by gusts of solar wind which trigger magnetic storms around the comet akin to geomagnetic storms which fuel auroras on Earth.
BBC News
Sat, 10 Nov 2007 08:35 EST
A supposed asteroid, which it was feared was going to have a near-miss with Earth next week, has been identified as a spacecraft.
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| ©ESA |
| The unmanned Rosetta craft has already flown past Earth once |
Professor Alan Fitzsimmons of Queen's University Astrophysics Research Centre told the BBC there is "no longer any need for concern".
"The 'asteroid' has been identified as the European spacecraft Rosetta," he said.
The spacecr
aft is en route to a comet near Jupiter.
Earlier this year, the unmanned Rosetta craft, which has already flown past Earth once, passed within 250 km (150 miles) of Mars.
In a precise move, the probe used the planet's gravity to change course on its voyage to the Churyumov-Gerasimenko comet.
Helen Altonn
Star Bulletin
Sun, 11 Nov 2007 17:13 EST
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| ©University of Hawaii |
| A comparison of Comet Holmes, the sun and Saturn (inset) is shown in this image from the University of Hawaii. |
Once a faint, obscure comet, 17P/Holmes has eclipsed the sun as the largest object in the solar system and it's still growing, Hawaii astronomers say.
The spectacular comet has dazzled astronomers since it exploded Oct. 24 from a tiny nucleus of ice and rock about 2.2 miles in diameter.
On Friday, the mass of ejected dust was measured at 900,000 miles across by Rachel Stevenson, Pedro Lacerda and Jan Kleyna of the University of Hawaii Institute for Astronomy.
They used observations from the Canada-France-Hawaii Telescope on Mauna Kea, which has a wide-field camera capable of capturing the whole comet in one image, the astronomers said.
Also participating in the research were astronomy professor David Jewitt, researcher Nuno Peixinho and graduate student Bin Yang.
People can see the comet as a fuzzy object with the unaided eye but it's much better with binoculars, Jewitt said.
The comet is expanding at about 1,100 mph and is "an unprecedented million times brighter" than before its outburst, UH astronomers said.
The comet's nucleus appears as a white "star" near the center of the cloud of dust on the image. A tail also is starting to grow, the scientists reported.
Jewitt said about 10 million tons of dust erupted from the comet.
"It's like something broke on the nucleus and all this stuff poured out into space," he said.
The comet was discovered in an outburst in November 1892, then faded and burst again in January 1893, he said. Both outbursts were almost the same size, Jewitt said, explaining they probably occurred when the comet was at its closest to the sun and were triggered by the sun's heat.
The IFA team will continue observations from Mauna Kea in case the comet follows the same pattern as it did more than 100 years ago, he said. "The comet is well placed in the sky for a long time so we'll be able to follow it from Mauna Kea for many, many months."
Comet Holmes, with an orbit period of about six years, is in a class of "Jupiter Family Comets" with orbits influenced strongly by Jupiter, the astronomers said.
It's believed these objects orbited the sun beyond Neptune in the Kuiper Belt region for most of the last 4.5 billion years, they said.
In a few thousand years, the astronomers said the comet is likely to either hit the sun or a planet, be ejected from the solar system, or simply run out of gas and disappear.
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| ©Sky and Telescope |
CQ Congressional Testimony
Thu, 08 Nov 2007 08:51 EST
Statement of Donald K. Yeomans Manager, NEO Program Office Jet Propulsion Laboratory
Committee on House Science and Technology Subcommittee on Space and Aeronautics
Mr. Chairman and members of the Subcommittee, thank you for the opportunity to appear today to discuss the potential threats of near-Earth objects (NEOs), our progress toward meeting the discovery goal articulated in the NASA Authorization Act of 2005, the role of the Arecibo planetary radar within the NEO program and the response options available if a NEO is found to be on an Earth impacting trajectory.
The Near-Earth Object Population: When the Earth was young, frequent collisions of comets and asteroids likely delivered much of the water and carbon-based molecules that allowed life to form, and once life did form, subsequent collisions may have punctuated the evolutionary process and allowed only the most adaptable species to progress further. We may owe our very existence atop the world's food chain to these objects. As the Earth's closest neighbors (some pass within the moon's distance), these icy comets and rocky asteroids have been termed near-Earth objects. Their proximity to Earth presents an opportunity to utilize their vast metal, mineral and water ice resources for future space structures and habitats. Their water resources can be broken down into hydrogen and oxygen - the most efficient form of rocket fuel. These near-Earth objects may one day be the resources, fueling stations and watering holes for human interplanetary exploration. While these objects are of extraordinary scientific interest, likely enabled the origin of life itself, and may loom large for the future development of space exploration, their proximity to Earth also presents a potential horrific threat should a relatively large near-Earth object once again strike Earth without warning. Potentially Hazardous Asteroids: Near-Earth objects are comets and asteroids that can pass within 45 million kilometers of the Earth's orbit. While some showy, naked-eye comets may occasionally pass close to Earth, it is the difficult to find (but far more numerous asteroids) that are of most concern in near-Earth space today. About one fifth of the near-Earth asteroids can approach the Earth's orbit even closer (to within 7.5 million kilometers), and these so-called potentially hazardous asteroids (PHAs) are of most concern for near-term hazard avoidance.
Celestial debris hits the Earth all the time, but the vast majority of it is so small that it does not survive passage through the Earth's atmosphere. The debris is created over millions of years, as asteroids inevitably run into each other, producing smaller fragments, which themselves collide yielding even more debris. Over time, the fragments and debris spread out, and some of it migrates into Earth approaching orbits. The Earth is pummeled with more than 100 tons of impacting material each day but almost all of it is far too small to cause anything other than a harmless meteor, or shooting star, or the occasional fireball event. Larger objects are less numerous than smaller objects and hit the Earth less often. While a basketball-sized object strikes the Earth's atmosphere daily, larger car-sized impactors hit only a few times each year, and even these generally break up into smaller pieces as they streak through the atmosphere. Occasionally a fragment of a larger impactor will reach the Earth's surface -- one such hit may have occurred less than two months ago when a reported asteroid fragment perhaps one meter in diameter struck in southern Peru creating a 13-meter crater near Lake Titicaca.
Larger impactors with diameters in the 50 to 140 meter range, while they do not usually impact the ground, can result in damaging air blasts that cause significant destruction. For example, on June 30, 1908, an impactor with a diameter of about 50 meters detonated over the Tunguska region of Siberia and leveled trees for 2000 square kilometers. Its impact energy has been estimated at about 10 million tons of TNT explosives (10 megatons or 10 MT), comparable in energy with a modern nuclear weapon. Roughly speaking, PHAs that have diameters larger than 140 m can punch through the Earth's atmosphere and cause regional damage if they strike land or create a harmful tsunami should they impact into an ocean. There are thought to be about 20,000 PHAs in this size range, each with a potential impact energy of 100 MT or more. On average, one of these objects would be expected to strike Earth every 5000 years and therefore would have a 1% probability of impact in the next 50 years. Although their mean impact frequency would be about once every 500,000 years, PHAs larger than a kilometer in diameter could cause global consequences due to not only the extraordinary blast itself (50,000 MT) but also the dust and debris thrown into the air, and the subsequent firestorms and acid rain. The extinction of the dinosaurs and a sizable fraction of the Earth's other species some 65 million years ago is thought to be due to an impactor with a diameter of about 10 kilometers that created an impact energy of as much as 50 million MT. Over very long time intervals, PHAs with diameters greater than one kilometer are statistically the most dangerous objects because their impacts would cause global consequences.
NASA Responses to the PHA Issues: In 1998, before the Subcommittee on Space and Aeronautics, a NASA representative outlined the goal to discover and catalog 90% of the NEOs larger than one kilometer by the end of 2008. There are currently thought to be over 900 of these objects, and about 80% of them have already been found and cataloged. Roughly the same percentage of PHAs in this size range has also been found. When this goal has been reached, 90% of the global risk from PHAs would be retired. Almost all of these discoveries have come by way of NASA supported search programs.
As part of the NASA Authorization Act of 2005, NASA was asked to consider options for extending the search down to objects as small as 140 meters in diameter, and to find and catalog them within 15 years of the Act becoming law (i.e., by the end of 2020). By finding and cataloging 90% of this population of PHAs, the statistical or actuarial risk to Earth from PHAs of all sizes would be reduced by 99% from pre-survey levels. We can speak of risk reduction in this case because once an object is discovered and cataloged, its future motion can accurately be predicted and, in the unlikely case where it does threaten Earth, there would be sufficient time to deflect it, thus saving the enormous costs due to fatalities and/or infrastructure damage. According to a 2003 NASA NEO Science Definition Team study that undertook a cost/benefit analysis for the discovery of PHAs, the risk reduction accruing from this next generation PHA search would pay for itself in the first year of operations. While an impact by a 140 meter-sized object would not generate global physical consequences, its impact energy would still be about 100 MT, and the likelihood of one of these impacts is 100 times greater than an impact by one of the less numerous one kilometer-sized PHAs. With regard to the uncertainty associated with threats from PHAs, the largest factor, by far, is the large number of undiscovered objects in the size ranges that are small enough to be very numerous but large enough to easily penetrate the Earth's atmosphere. For example, we have discovered only about 4% of the 20,000 PHAs larger than 140 meters and less than 1% of the 200,000 objects larger than 50 meters. The solution to this uncertainty is to continue and hopefully accelerate the search for PHAs. Once we find the vast majority of them, they can be tracked, cataloged and then ruled out (or in) as threats during the next 100 years or so. This process can continue year after year so the window of safety is always at least 100 years. There are other, less significant, uncertainties dealing with the refinement of a particular object's size, mass and structure as well as the dynamical model that is used to accurately predict the object's motion over 100 year time scales. For example, over long time intervals, the minute pressure of sunlight and its thermal re-radiation can significantly affect a PHA's motion. For a select number of Earth approaching objects, we will need the use of the planetary radars, or possibly rendezvous spacecraft missions, to better understand their sizes, shapes, masses, surface properties, and possible binary natures.
The Next Generation of Search: As noted, the current NASA NEO goal is focused upon the discovery and tracking of objects one kilometer in diameter and larger. It is not realistic to expect the current survey program, with its modestly sized telescopes, to efficiently find the 140 meter-sized objects that are nearly 50 times fainter compared to a one kilometer-sized object at the same distance and with the same reflectivity. Because all PHAs do eventually come very close to the Earth, the current ongoing surveys could complete the goal outlined in the 2005 NASA Authorization Act but it would likely take over a century to do so. We cannot afford to wait that long.
In the report to Congress requested by the 2005 NASA Authorization Act, several options were outlined, both ground- based and space-based, that could meet the goal of finding 90% of the PHAs larger than 140 meters by the end of 2020. For example, a one-meter aperture infrared telescope in a heliocentric orbit near Venus could do the job three years early. Within this report, NASA noted that it did not have the resources to carry out a survey option that would meet the 2020 deadline set by the 2005 Act and that, in an attempt to achieve the legislative goal by the end of 2020, it would seek to continue the current survey programs and look for opportunities to use dual use telescope facilities and spacecraft along with partnering with other agencies as feasible.
At least two next-generation, ground-based, wide-field search telescope surveys are in development. The Panoramic Survey Telescope and Rapid Response System (PanSTARRS), under development at the University of Hawaii with Air Force funding, will have one of its four 1.8 meter telescopes operational in Hawaii in early 2008. If the planned, four telescope version of PanSTARRS is completed by 2010, it could help reach the goal by about 2040. Likewise the 8.4 meter aperture Large Synoptic Survey Telescope (LSST) that is under development with funding from NSF, DoE and other partners, could help reach the goal by about 2034 if it began operation in 2014. If we assume that both the PanSTARRS four telescope system and the LSST operate in their planned shared modes, which includes many observations unrelated to PHAs, then the goal could be reached by about 2026. The PHA discovery rate could be increased beyond the results shown in the NASA response to the 2005 Act if the observing time and sequences of PanSTARRS and LSST were optimized for PHA observations.
In terms of actual discoveries of new PHAs, there has been little success beyond the survey programs supported by NASA. However, the international community, including many sophisticated amateur astronomers, is very active in providing the follow-up observations necessary to secure an object's orbit once it has been found. The NEODyS program in Pisa Italy works closely with, but independent of, the NEO Program Office at JPL to compute impact probabilities for predicted Earth close approaches for at least 100 years into the future. It is also encouraging to note the activities of a NEO Action Team within the UN Committee on the Peaceful Uses of Outer Space (COPUOS) includes an effort to encourage more international efforts on the NEO issues.
The importance of Radar Observations: There are only two planetary radars in existence (and no alternatives) that can routinely observe close Earth approaching asteroids, and both of them are critically important for investigating the nature of these objects and for rapidly refining their trajectories. The 70- meter Goldstone antenna in California's Mojave desert is fully steerable, can track an asteroid and can cover large regions of sky while the larger 305-meter Arecibo antenna in Puerto Rico has twice the range but only observes within a 40-degree zone centered on the overhead position (20 degrees on either side of zenith). The capabilities of these two telescope complement one another and often a significantly better and longer set of observations can be achieved using both radars on a close approaching target asteroid.
Most positional data for PHA orbit determination and trajectory predictions are based upon optical, plane-of-sky observations. Because the radars provide line-of-sight velocity and range information accurate to about the 1 mm/s and 10 meter levels, these data when used in conjunction with the optical data provide a secure orbit and trajectory far more rapidly than if only optical data are available. With only a limited amount of optical data to work with, the orbit of a newly discovered PHA is often not accurate enough to immediately rule out a future Earth impact. However, with radar data in hand, the orbit of a newly discovered PHA can be quickly and more precisely determined, its motion accurately projected far into the future and future impact possibilities can usually be quickly ruled out. Likewise, in the rare situation when an object is actually on an Earth threatening trajectory, radar observations will be critical in quickly identifying this case.
Unfortunately the Arecibo radar program is not funded by the NSF beyond FY2007 and the planetary science community is in danger of losing one of its instrumental crown jewels. As a measure of this radar facility's importance, note that 65% of all radar experiments to characterize near-Earth asteroids were performed at Arecibo, 47% of all binary near-Earth asteroids were discovered at Arecibo and 85% of the near-Earth asteroids with the critical astrometric radar data for orbit improvement have data from Arecibo. All of this was accomplished with only 5% of this instrument's time. The superior sensitivity of the giant Arecibo radar can determine the sizes, shapes, rotation characteristics, surface characteristics and binary nature for many PHAs. All of these physical characteristics are important criteria to understand before a deflection mission is considered. Radar observations are responsible for the best physical characterization of any PHA as large as a kilometer (i.e., the binary asteroid 1999 KW4). Radar observations reduce a PHA's orbit uncertainties quickly and dramatically so that future impact possibilities can be quickly knocked down thus reducing the odds that we will need to invest in a spacecraft investigation to characterize the PHA's nature in preparation for a precautionary deflection mission. Thus the relatively modest costs of maintaining the Arecibo radar in a robust state could prevent the future need for 100's of millions of dollars per case for spacecraft reconnaissance of an object to determine whether or not it is an actual threat.
What Should be Done in the Event of an identified NEO Threat? A number of existing technologies can deflect an Earth threatening asteroid - if there is time. The primary goal of the PHA survey programs is to discover them early and provide the necessary time. An asteroid that is predicted to hit Earth might require a change in its velocity of only 3 millimeters per second if this impulse were applied twenty years in advance of the impact. The key to a successful deflection is having sufficient time to carry it out, whether it is the slow, gentle drag of a gravity tractor or a more impulsive shove from an impacting spacecraft or explosive device. In either case, a verification process would be required to ensure the deflection maneuver was successful and to ensure the object's subsequent motion would not put it on yet another Earth impacting trajectory. While suitable deflection technologies exist, none of them can be effective if we are taken by surprise. It is the aggressive survey efforts and robust planetary radars that must ensure that the vast majority of potentially hazardous objects are discovered and tracked well in advance of any Earth threatening encounters. The first three steps in any asteroid mitigation process are: Find them early, find them early, and find them early!
Lee Pullen
Astrobio.net
Mon, 12 Nov 2007 20:45 EST
Jupiter is known as many things: king of the planets, an impressive gas giant, defender of the inner solar system. This last notion comes from the idea that Jupiter is so massive that its gravitational influence deflects objects like comets, which, as they spiral toward the Sun, could potentially hit inner planets such as the Earth.
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| ©Unknown |
| Comet impacts pose a serious threat to life on Earth. |
Without Jupiter acting as a "cosmic vacuum cleaner" sucking up these dangerous objects, there would be so many catastrophic impacts that life probably wouldn't have evolved on the Earth and we wouldn't be here today. At least, this is the commonly accepted wisdom. Like so many topics in astrobiology, it isn't as straightforward as it first seems. Jonti Horner and a team from the UK's Open University have been addressing the question of whether Jupiter is our friend or foe.
"This vacuum cleaner idea goes back to when the long-period comets coming in from the Oort Cloud were viewed as being the only significant impact risk," says Horner. "In the 1950s there were only one or two near-Earth asteroids known, so they were viewed as oddities."
Astronomers in the 1950s realised that comets were approaching the solar system from extreme distances - so far away that the Sun, Jupiter, and other planets were essentially a single point-source of gravitational influence. When the comets got close enough to resolve the Sun and Jupiter as separate objects, they then had different forces pulling at them, resulting in a change of direction.
"The comets get a very slight kick, an increase in energy, from Jupiter," says Horner. "For these comets, Jupiter stops them from coming back time and time again; Jupiter makes them leave. The great majority of long-period comets only come through once but they have a very small chance of hitting the Earth."
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| ©Unknown |
| Jupiter can act as a shield, soaking up impacts as happened in 1994 with comet Shoemaker-Levy 9. |
Since the 1950s, scientists have discovered more objects in the solar system, and they say many of them could collide with us. The objects are found primarily in the asteroid belt between Mars and Jupiter, but a few remnants from the planet formation era 4.6 billion years ago are dotted around the solar system. Horner believes it's these two groups of asteroids - and not comets - that are most dangerous to life on Earth.
"Occasionally there are collisions between these objects, and when they collide they get nudged onto different orbits and into unstable regions," says Horner. "Then Jupiter can start to perturb them and nudge them around. That's where we get the near-Earth asteroids from, and these are now perceived to be the greatest risk to our planet."
But just how common are these impacts? Do they occur often enough to endanger life? Horner and many other scientists believe so. Part of the danger depends on the size of the object. It's been estimated that about 75 million meteors hit the Earth every day, but because they are typically no bigger than a grain of sand, they'll just leave a pretty trail in the night sky. It's not these tiny meteors that concern Horner, it's their larger relatives that inhabit the solar system.
"The bigger they are, the less frequent the impacts are, but the more interesting they become, and certainly more threatening," says Horner. "A figure that's banded around is that a one kilometer-sized object would hit the Earth on average every 300,000 years. A one kilometer object is the threshold between being a locally-damaging event and a globally-damaging event. Bigger than this, and you get a lot of people falling over."
It's not just the size or frequency of impacts that has to be taken into consideration. Speed also is an important factor. Doubling the velocity can put four times more energy into the impact.
"The long-period comets are more of a threat at a given size because they hit harder and faster," says Horner. "With the near-Earth asteroids, you'd need a bigger object hitting us to have the same amount of devastation."
Horner and his team reasoned that for a planet to be habitable over appreciable periods of time, it would have to somehow avoid impacts of extinction-level size and speed. However, smaller and slower impacts also may stop life from developing if they hit regularly enough.
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| ©Unknown |
| Horner's graph simulates impact rates on the Earth over a ten million year timescale. Changing the mass of Jupiter has a dramatic effect. |
Despite the apocalyptic potential of asteroids and comets, Horner's research suggests we're more likely to find habitable worlds elsewhere in the galaxy. He says that the presence of a gas giant planet isn't as important as everyone thinks, and that means there is greater wiggle room in our definition of what makes a solar system habitable. He also theorises that impacts may not always be detrimental to life -- in fact, they may be essential.
"It may be that if you have too few impacts, life will stagnate," he says. "It may even be that our Earth is not the ideal in terms of intelligent life evolving. Maybe we have too few impacts, which is why it's taken us four and a half billion years to get here."
However, until life is found elsewhere scientists can only guess at what environmental conditions are best for intelligent life to evolve and persist. In the meantime, Horner's results may cause us to alter our ideas of where life could form, and the conditions under which it can develop. The next step in his research is to look at the effect of smaller planets, such as Neptune. Could it be that they have more of an influence on our own world than we currently believe? Horner also hopes to use complex computer simulations to move Jupiter into different orbits, experimenting with how the distance of a gas giant from a habitable world affects impact rates. Jupiter may well have more surprises in store.
icRenfrewshire.co.uk
Mon, 12 Nov 2007 09:30 EST
Stargazers will be in seventh heaven when one of the most spectacular sights in the night sky becomes visible above Paisley.
And, to make the outlook even brighter, Buddies won't even need binoculars or telescopes to identify the celestial wanderer.
They'll see it all with the naked eye.
 |
| ©Sky and Telescope |
Comet Holmes, first discovered in 1892 by English amateur astronomer Edwin Holmes, has now come back into view during its seven-year orbit around the Sun.
And, during the next few weeks, it will be seen as a yellow-coloured star surrounded by a hazy cloud in the constellation Perseus, which begins its nightly journey in the north-east sky - that's in the Glasgow direction.
One man who'll have his head in the clouds while it's all happening will be top astronomer John Pressly, information officer at Coats Observatory in Paisley.
"What makes Comet Holmes unusual is that it literally brightened overnight, from a very faint object detectable only with a powerful telescope to an object visible to the naked eye," said Mr Pressly. "The comet has just become one million times brighter than it had been, most likely because of explosions within it.
"These explosions ejected a massive cloud of dust surrounding the centre. This dust cloud reflects sunlight, which is why we can see it so easily.
"A comet is like a dirty snowball, composed of dust and gas, which periodically orbits around our sun. Comets are believed to be the leftovers from the time that the planets formed and could even contain clues to the origins of life on our planet.
"The centre of the comet is known as the nucleus. As the comet nears the sun, it will start to melt, giving off dust and gas, which usually forms in a tail at the back of the comet, pointing away from the Sun."
Mr Pressly added: "Comet Holmes can be seen in the constellation of Perseus, which rises in the early evening and which should be high enough in the sky by 8pm for people to be able to find the comet.
"The easiest way to find it is to look for the distinctive W shape of the constellation Cassiopeia, high in the north-eastern sky. Perseus lies just below Cassiopeia.
"Comet Holmes looks different than the surrounding stars, shining with a constant, yellowish colour as opposed to the bluish twinkling light of the surrounding stars.
"At present, Comet Holmes is some 150 million miles from Earth and should stay at this distance as it orbits the Sun.
"The comet is visible to the naked eye, even with the heavily light polluted skies of Paisley.
"Through binoculars, it looks like a circular hazy cloud, very different from the background stars.
"In our telescope at the observatory, the nucleus should be visible as a faint point of light surrounded by a cloud of bright dust."
Buddies who want to see the comet at close quarters are being invited along to the observatory in Oakshaw Street West.
They'll get the chance when Mr Pressly and his colleagues at the observatory train their large telescope on the cosmic comet to allow visitors a chance to see for themselves the rare sky marvel.
The observatory will be open to the public on Tuesday and Thursday nights from 6.30pm to 9.30pm, with last admission at 9pm. Entry is free and there is no need to book. Viewing is only possible on clear windless evenings.
Physorg.com
Mon, 12 Nov 2007 09:40 EST
 |
| ©NASA |
| Artist's concept of a catastrophic asteroid impact |
Hollywood thrillers such as Deep Impact helped to jump-start America's interest in knowing what our "deflection strategy" would be if a giant asteroid was on a potentially catastrophic collision course with Earth.
Chris Palma, senior lecturer in astronomy and astrophysics at Penn State, says that such events are statistically highly probable. "Throughout Earth's history, we have been bombarded by comets and asteroids from space," Palma notes. "Impacts happened more frequently in the past, but they will happen again. It is just a matter of when."
Explains Palma, a law was passed two years ago requiring NASA to "to both survey for near Earth objects and come up with a plan to divert those objects." Yet, some experts have criticized both NASA and the United States government for not doing enough to prevent potential impacts with Earth.
The so-called Tunguska event in 1908, believed to have been the only large-scale meteorite hit within recorded human history, reportedly flattened over 830 square miles of Siberia, with an explosion a thousand times more powerful than the atomic bomb dropped on Hiroshima. While it is staggering to imagine such damage in a heavily populated area, Palma cautions that "we have no experience with these scenarios and can't do more than estimate the number of lives that will be lost and the amount of damage to the infrastructure in the impact region."
Programs have been set into place to help predict and monitor threats posed by meteorite and asteroid impacts, such as NASA's Near Earth Object Program and University of Arizona's SpaceWatch group. However, Palma's impression is that the majority of similarly focused programs are spearheaded by "individual researchers."
What would happen if an asteroid was detected heading toward Earth? A number of different ideas have been proposed, says Palma, including "sending a very massive unmanned spacecraft towards the asteroid and using the ship's gravitational pull to nudge the asteroid off course." Adds Palma, the idea isn't to physically push it, but rather to use the spacecraft's strong gravitational pull to cause the asteroid to move into a different orbit without directly impacting the asteroid."
Would such a dramatic, heroic endeavor succeed? "My guess," says Palma," is that this particular model is a good theoretical starting point, but not one that is necessarily going to be feasible if applied."
Is enough being done to prepare for potential threats? As with so much else, it all depends on who you ask, though all agree that the stakes are high. After all, the most popular explanation for dinosaur extinction is the widespread after-effects of a giant asteroid impact.
Regarding our current state of deflection readiness, Palma says, "I think it is a bit of a stretch to say that NASA is doing nothing about this, but at the same time, I think you can argue that they should be doing more."
thunderbolts.info
Tue, 13 Nov 2007 22:44 EST
Spacecraft have now visited four comets. What they found contradicts what was expected and falsifies accepted comet theory. But that theory is woven with every other astronomical theory into a cosmology that defines the universe as we know it. The fall of comet theory will inevitably bring us a new and different universe.
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| ©NASA/JPL/Malin Space Science Systems |
| Comet Wild 2 is shown in close-up above. Beside it is a microscopic view of an EDM (electrical discharge machined) surface. Note the flat-floored depressions with steep scalloped walls and terracing. The small white spots on the comet can then be reasonably identified as the active cathode arcs that produce the cometary jets. |
Comets are giving accepted comet theory a hard time. Close-up images of comet nuclei from spacecraft have contradicted about every expectation of theory. ("Expectation" is a euphemism for "prediction"; a disappointed expectation is practically the same thing as a failed prediction, except with the former you don't expect you'll have to discard the theory.) "If astronomy were a science," as one astronomer put it, theoreticians would admit that the theory had been falsified, and they would start over with an eye to the evidence. Instead, they hang on to the theory with ever more stubbornness and hope a little tinkering and adjusting will bring the facts into line.
The facts are apt to be more stubborn than the theoreticians: Deep Impact kicked up ten times more dust than expected and stimulated the comet's activity a magnitude less than expected. The dust was not a conglomeration of sizes as expected but was consistently powder-fine. The nucleus of the comet was covered with sharply delineated features, two of which were circular enough to be called impact craters. This was not expected for a dirty snowball or a snowy dirtball or even a powdery fluffball.
The craters, of course, weren't actually called impact craters. They must have been caused by subsurface explosions, because they had flat floors and terraced walls, despite the myriad of other craters on rocky planets and moons with flat floors and terraced walls that are called impact craters. All the other circular depressions with flat floors and terraced walls weren't craters because they had "unusual shapes."
The hard times began with Comet Halley. Theory expected more or less uniform sublimation of the surface as the nucleus rotated in the sun, much as you would expect of a scoop of ice cream on a rotisserie. But Halley had jets. Less than 15% of the surface was sublimating, and the ejecta was shooting away in thin beams.
The theory was adjusted to introduce hot spots, chambers below the surface in which pressure could build up and erupt through small holes to produce the jets. It went unmentioned that the holes must have been finely machined, like the nozzle of a rocket engine, in order to produce the collimation of the jets: Just any rough hole would result in a wide spray of gases.
Borrelly made the hard times harder. It was dry. And black. Theoreticians tinkered with the dirty snowball theory until they got the dirt to cover the outside and to hide the snow inside. Somehow they got the dirt, which ordinarily is an insulator, to conduct heat preferentially into the rocket chambers to keep the jets going.
Wild 2 defied them. Its jets were not just around the sub-solar point, where the Sun's heat would be greatest. This comet sported jets on the night side. The rocket chambers now had to store heat for half a "comet day". And something was needed to keep the jets coherent over great distances and to gather their emissions into a stream of clumps: Clusters of particles repeatedly struck the spacecraft.
Comet theorists announced that comets were mysteries and that the theorists knew nothing, that they had to "think differently". Then they proposed adjustments to the accepted theory that would be acceptable to the accepted way of thinking.
Different theories abound - but outside the walls of astronomical acceptability. For an astronomer to recognize their existence would be to jeopardize his position and salary. But the characteristics of comets that are so difficult to explain with snowballs are fairly easy to explain with electricity.
Electrical theories date back to the 1800s, before "electricity" became taboo in astronomy. They were well-founded on observations and on the proven laws of electromagnetism. In the last few decades, they have been refined to the point where they expected the findings that were so hard on the fashionable theory:
Comets are electrical discharges in the thin plasma that permeates the solar system. Because they spend most of their time far from the Sun, their rocky nuclei are in equilibrium with the voltage at that distance. But as they accelerate in toward the Sun, their voltage is increasingly out of equilibrium with the voltage and increasing density of the solar plasma. A plasma sheath forms around them - the coma and tail. And filamentary currents - jets - between the sheath and the nucleus erode, particle by powdery particle, the circular depressions with terraced walls that are typical of electrical discharge machining. As the discharge channels move across the surface of the comet, they burn it black.
If it were only a matter of explaining with plasma discharges the jets and the blackened rocky surfaces and the powder-fine dust and the terraced depressions, there might not be so much blinkered stubbornness. But modern astronomical theories have been worked into an interlocking web of explanation. Each theory supports, and is in turn supported by, nearly every other theory. If one theory frays, if one loose thread is pulled, the entire fabric will unravel.
An electrified comet requires an electrified Sun. The Sun is the focus of the electric field that causes the comet to discharge. For the Sun to maintain its electric field, it (and all stars) must be the focus of another electric discharge within an electrified galaxy. And electrified galaxies, with their magnetic fields and x-ray emissions and ejections of quasars, must be connected in larger circuits that render meaningless such fancies of cosmology as the Big Bang theory.
If you pull one electrified comet out of the well-knit structure of accepted theories, the entire garment will become unacceptable. Either the universe is an agglomeration of isolated, gravitating, non-electrical bodies, or else it is a network of bodies connected by and interacting through electrical circuits. Either the universe is a gravity universe or it is an Electric Universe.
And comets are the loose thread.
David Jewitt
University of Hawaii
Thu, 15 Nov 2007 04:04 EST
Formerly, the Sun was the largest object in the Solar System. Now, comet 17P/Holmes holds that distinction.
Spectacular outbursting comet 17P/Holmes exploded in size and brightness on October 24. It continues to expand and is now the largest single object in the Solar system, being bigger than the Sun (see Figure).
The diameter of the tenuous dust atmosphere of the comet was measured at 1.4 million kilometers (0.9 million miles) on 2007 November 9 by Rachel Stevenson, Jan Kleyna and Pedro Lacerda of the University of Hawaii Institute for Astronomy.
They used observations from a wide-field camera on the Canada-France-Hawaii Telescope (CFHT), one of the few professional instruments still capable of capturing the whole comet in one image. Other astronomers involved in the UH program to study the comet include Bin Yang, Nuno Peixinho and David Jewitt.
The present eruption of comet Holmes was first reported on October 24 and has continued at a steady 0.5 km/sec (1100 mph) ever since. The comet is an unprecedented half a million times brighter than before the eruption began. This amazing eruption of the comet is produced by dust ejected from a tiny solid nucleus made of ice and rock, only 3.6 km (roughly 2.2 miles) in diameter.
 |
| ©Sun and Saturn images courtesy of NASA's SOHO and Voyager projects |
| (Left) Image of comet Holmes from the 3.6-meter Canada-France-Hawaii telescope on Mauna Kea showing the 1.4 million km diameter coma. The white ''star'' near the center of the coma is in fact the dust-shrouded nucleus. (Right) the Sun and planet Saturn shown at the same scale for comparison. |
The new image also shows the growth of a tail on comet Holmes (the fuzzy region to the lower right in the comet picture), caused by the pressure of sunlight acting on dust grains in the coma.
Over the next few weeks and months, the coma and tail are expected to expand even more while the comet will fade as the dust disperses. Comet Holmes showed a double outburst in November 1892 and January 1893. It is not known if the present activity in the comet will follow the pattern from 1892, but continued observations from Mauna Kea are planned to watch for a second outburst. Most comets show small fluctuations in brightness and some have distinct outbursts.
The huge event on-going in comet Holmes is unprecedented, however.
The orbit period of comet Holmes is about 6 years, putting it in the class of Jupiter Family Comets whose orbits are strongly influenced by Jupiter. These objects are thought to have spent most of the last 4.5 billion years orbiting the Sun beyond Neptune, in a region known as the Kuiper Belt. Holmes probably was deflected into its present orbit within the last few thousand years and is losing mass as it evaporates in the heat of the Sun.
In another few thousand years it is likely either to hit the Sun or a planet, be ejected from the Solar system, or simply die by running out of gas.
Contacts Rachel Stevenson [rach@ifa.hawaii.edu 808-956-6680] David Jewitt [jewitt@ifa.hawaii.edu 808-956-7682]
Comment: The same image is available from the University of Hawaii as a 300 dpi tif file.
Julie Steenhuysen
Reuters
Thu, 15 Nov 2007 23:10 EST
The normally sedate Comet Holmes made a bright splash in the sky about two weeks ago, unexpectedly becoming a million times brighter than normal overnight and causing a stir among astronomers.
 |
| ©REUTERS/NASA, ESA, and H. Weaver/The Johns Hopkins University Applied Physics Laboratory/Handout |
| A Hubble image (R), taken November 4, 2007, shows the heart of Comet 17P/Holmes. The central portion of the image has been specially processed to highlight variations in the dust distribution near the nucleus. About twice as much dust lies along the east-west direction (the horizontal direction) as along the north-south direction (the vertical direction), giving the comet a "bow tie" appearance. The composite color image at left, taken on November 1, 2007, by an amateur astronomer shows the complex structure of the entire coma, consisting of concentric shells of dust and a faint tail emanating from the comet's right side. |
The comet and its expanding ball of dust have become the biggest object in the solar system, with a diameter appearing even bigger than the sun, according to astronomers at the University of Hawaii Institute for Astronomy.
The fireworks began on October 23, when the comet brightened in a 24-hour period. It is now fading but can still be seen by the naked eye in the northeastern sky.
"Something that spectacular is almost like a supernova going off," said Hal Weaver, a comet expert at The Johns Hopkins University Applied Physics Laboratory.
"Now, we're trying to observe the event and figure out what the heck happened," Weaver said in a telephone interview on Thursday.
Weaver and fellow astronomers, using the powerful Hubble telescope, have some clues that may help explain the display. So far they have noticed that the comet's nucleus, the small solid body that is the main source of all the comet's activity, is still surrounded by dust.
He and colleagues believe some sort of explosion sheared off a pancake-shaped slab of the comet, which crumbled into tiny dust particles that are being lit up by the sun.
Hubble images of the comet from June 1999 showed no dusty halo. At that time, they measured the comet's nucleus at some 2.1 miles, about the length of New York City's Central Park.
DELAYED EFFECT
They are now hoping to examine the comet's size to see how much of it was sheared away in the blast.
Weaver said comets typically get most active when they are nearest to the sun, but Comet Holmes, known officially as 17P/Holmes, made its closest approach to the sun six months ago.
One reason he offered for the delayed effect was the presence of volatile ice made up of carbon monoxide, dry ice, ethane, methane and acetylene and hydrogen cyanide. These, he said, may have gotten heated up but could not escape the comet's nucleus, causing a build-up of pressure that eventually exploded.
Weaver also thinks there might be a seasonal effect, in which different portions of the comet's nucleus are visible only at certain points of the comet's orbit around the sun, which happens every seven years.
Comet Holmes put on a similar display in 1892, which astronomers believed was caused by a collision with another comet, which sliced off a piece of Holmes' nucleus that slammed back into it again, sending up a showy spray of dust.
"Now, we step forward to 2007, and the same thing is happening again. It indicates that hypothesis is incorrect," Weaver said.
While the magnitude of the light show is spectacular, he said comets do tend to flare up every now and then.
(Editing by Will Dunham and Xavier Briand)
Dr Derek Ward-Thompson
Cardiff University
Tue, 03 Feb 2004 17:46 EST
Scientists at Cardiff University, UK, believe they have discovered the cause of crop failures and summer frosts some 1,500 years ago - a comet colliding with Earth.
The team has been studying evidence from tree rings, which suggests that the Earth underwent a series of very cold summers around 536-540 AD, indicating an effect rather like a nuclear winter.
The scientists in the School of Physics and Astronomy believe this was caused by a comet hitting the earth and exploding in the upper atmosphere. The debris from this giant explosion was such that it enveloped the earth in soot and ash, blocking out the sunlight and causing the very cold weather.
This effect is known as a plume and is similar to that which was seen when comet Shoemaker-Levy-9 hit Jupiter in 1995.
Historical references from this period - known as the Dark Ages - are sparse, but what records there are, tell of crop failures and summer frosts.
The work was carried out by two Cardiff undergraduate students, Emma Rigby and Mel Symonds, as part of their student project work under the supervision of Dr Derek Ward-Thompson.
Their findings are reported in the February issue of Astronomy and Geophysics, the in-house magazine of the Royal Astronomical Society.
The surprising result of the new work is just how small a comet is needed to cause such dramatic effects. The scientists calculate that a comet not much more than half a kilometre across could cause a global nuclear winter effect. This is significantly smaller than was previously thought.
Dr. Ward-Thompson said: "One of the exciting aspects of this work is that we have re-classified the size of comet that represents a global threat. This work shows that even a comet of only half a kilometre in size could have global consequences. Previously nothing less than a kilometre across was counted as a global threat. If such an event happened again today, then once again a large fraction of the earth's population could face starvation."
The comet impact caused crop failures and wide-spread starvation among the sixth century population. The timing coincides with the Justinian Plague, widely believed to be the first appearance of the Black Death in Europe. It is possible that the plague was so rampant and took hold so quickly because the population was already weakened by starvation.
There's A Mystery Object Not Far From The Earth
New Scientist
Wed, 24 Feb 1999 15:14 EST
A chunk of rock some 50 metres across has been found circling the Sun in an orbit close to Earth's. The object, which was discovered on 10 February by an automated asteroid-hunting telescope in New Mexico called Linear, is probably a chip off the Moon, say astronomers.
After six nights of observations, Gareth Williams of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, calculated that it circles the Sun every 1.09 years. Its nearly circular orbit is just nine million kilometres farther from the Sun than the Earth's.
The object's orbit is extremely unusual. Comets and asteroids that cross the Earth's orbit normally have eccentric orbits. There is only one asteroid-like object, called 1991 VG, that has a similar orbit to that of the Earth. When it was discovered, eight years ago, astronomers thought it might be a spacecraft that had escaped the Earth's gravity.
The new object, designated 1999 CG9, is considerably brighter than 1991 VG, indicating that it is much larger. Brian Marsden of Harvard-Smithsonian estimates it to be between 30 and 50 metres across, too big to be the final stage of a rocket. "The most likely explanation is that it's a chip off the Moon," he says.
Although the Moon is small, its low gravity makes it easy to blast debris into orbit. "We have seen there are chips off the Moon," says Marsden. "Twelve small lunar meteorites have been found on the Earth."
"If you can shoot things off the Moon, they would continue to go around the Sun in an orbit not too different from the Moon," Marsden adds. So far, astronomers do not know the object's composition, which could cast light on its origins. However, the astronomers hope to analyse the rock's spectrum to see how it compares with that of the Moon.
Sara Dixon
Borehamwood and Elstree Times
Sat, 17 Nov 2007 17:19 EST
MYSTERY surrounds unidentified flaming objects which Borehamwood residents claim to have spotted in the night sky in the past two months.
On September 6, Khristian Rawlings was shocked to see two large balls of fire, the size and height of a large aeroplane, whizzing across the sky as he stood on the balcony of his home in Howard Drive.
A month later, on November 5, Lisa Talbot saw a brightly burning flying object, also travelling at the height of a plane, as she left a fireworks display at the town's Meadow Park.
Father-of-one Mr Rawlings, 24, said: "They came across at around 9.15pm. They were orange, and the only way I could describe them is as a bubble with a fireball in the middle. They were very bright, going at some speed, and travelling towards London.
"They were very small at first and I thought they were a blip on my glasses but they got bigger and I really thought something was amiss. It was a bit creepy.
"I was scared to death. I told my girlfriend to get the baby, but she told me to calm down and not go crazy."
Mr Rawlings believes the peculiar sight could have been Russian spy planes or meteors.
Miss Talbot, 37, spotted the other mysterious object, also travelling towards London, as she was returning to her Farriers Way home with her nine-year-old daughter.
She said: "It was like a flame going though the sky and the ball was turning around and around, glowing orange. The fireworks had finished and it couldn't have been a firework, it was burning for too long. Everybody stopped and stared at the object. It looked like a meteor.
"I immediately called my mother who had walked the opposite way to me, up Shenley Road towards the old Holmshill School site. She too had seen the object along with the crowd following her the same way. Everybody was totally dumbfounded by what it could have been.
"I'll be keeping an eye out on December 5, to see if they come back."
A spokesman for Hertfordshire Constabulary said police had received no reports of unidentified flaming objects.
Mystery Event In Australian Outback: Nuclear Blast, Earthquake Or Meteorite?
University of Colorado at Boulder
Wed, 28 May 1997 15:11 EDT
At the request of a U.S. Senate subcommittee on investigations, a group of scientists has been analyzing a mysterious seismic event that took place in a remote part of southwest Australia on May 28, 1993.
On that date, a group of aboriginal prospectors witnessed a radiant, star-like object traveling low across the horizon followed by a bright flash of light and a powerful explosion when the object disappeared behind a ridge. The terrorist group responsible for the March 20, 1995 poison gas attack in a Tokyo subway had attempted to enrich uranium near the epicenter of the mystery event, and Senate investigators feared the group was conducting nuclear tests in the area.
Scientists examining the event are Christal B. Hennet and Gregory E. van der Vink of Incorporated Research Institutions for Seismology in New York, Danny Harvey of the University of Colorado at Boulder, and Christopher Chyba of the University of Arizona. Harvey is a research associate at the Joint Seismic Program Center in the CU-Boulder physics department.
The researchers looked at factors such as location, depth and magnitude to distinguish between possible causes of the event, including an earthquake, a meteorite or an explosion. Their analysis ruled out a nuclear explosion and suggests an iron meteorite more than 3 meters in diameter may have been the cause of the mysterious blast.
The group, which presented its findings at this week's meeting of the American Geophysical Union in Baltimore on May 28, used seismic data collected from various stations in Australia to analyze the event.
Such a meteorite would have left a crater more than 90 meters in diameter, and the scientists are now attempting to define an area of impact so that a ground search can be undertaken.
Anton Wylie
The Register
Sun, 18 Nov 2007 19:56 EST
But what's a Comet, anyway?
|
| ©REUTERS/NASA, ESA, and H. Weaver/The Johns Hopkins University Applied Physics Laboratory/Handout |
| A Hubble image (R), taken November 4, 2007, shows the heart of Comet 17P/Holmes. The central portion of the image has been specially processed to highlight variations in the dust distribution near the nucleus. About twice as much dust lies along the east-west direction (the horizontal direction) as along the north-south direction (the vertical direction), giving the comet a "bow tie" appearance. The composite color image at left, taken on November 1, 2007, by an amateur astronomer shows the complex structure of the entire coma, consisting of concentric shells of dust and a faint tail emanating from the comet's right side. The normally sedate Comet Holmes made a bright splash in the sky about two weeks ago, unexpectedly becoming a million times brighter than normal overnight and causing a stir among astronomers. |
The Web is abuzz about Comet Holmes.
Comet 17P/Holmes had been expected to make just another routine ultra low visibility departure from perihelion passage this year. But in a record for a comet, it unexpectedly brightened by a factor of around a million on October 24, making it more reminiscent of a stellar nova explosion.
"Amateur astronomers the world over have been stunned and amazed by the weirdest new object to appear in the sky in memory," wrote Sky and Telescope.
"The comet shocked skywatchers as it went from a dim 17th magnitude then suddenly to 3 magnitude" wrote Theo from the Pacific Northwest.(*)
Holmes brightened from below the threshold of binoculars to being clearly visible with the unaided eye. The outburst presented as a circular fuzzy patch in the constellation of Perseus, and has proceeded to grow in size. The comet was then reported to have spawned a tail.
More drama was to come.
Spaceweather currently reports that "last Friday, astronomers watched in amazement as the comet's tail broke off!".
And Comet Holmes may yet make further news, should this be a prelude to the full-on fissioning of the comet's core into several pieces. The comet is expected to remain visible to the naked eye for some weeks.
Why did Comet Holmes flare up?
Yet Comet Holmes has brightened up unexpectedly on a previous
occasion: that of November 1892 led to its discovery by E. Holmes in
England. It was subsequently determined to be a periodic comet, with a
revolutionary period of about every seven years. You can see its orbit
in relation to other planets courtesy of Larry's animation here.
Much less, though, has been made of the fact of where it was when the current flare-up occurred. The Armagh Observatory's website puts the comet at some 230m miles from the Sun - a distance from, and quite a long time after, its closest point to the Sun, which occurred on May 4, 2007.
In the accepted view, comets are thought to comprise rocky and icy solids in a mixture termed "rocky snowballs" by some and "icy rockballs" by others. They get brighter and sprout tails as the "icy" component is thought to sublimate from solid to gaseous state under the influence of solar heating, which typically begins affecting them at a point just inside the orbit of Jupiter. This gives rise initially to an expanding light-reflecting aura known as the coma, which is then "blown away" in the opposite direction from the sun by the solar "wind".
Multiple repeated thermally-induced mechanical stresses are thought to give rise to a cometary aging process, whereby a large single core disintegrates after multiple closer solar encounters into much smaller fragments. When such orbiting debris intersects the Earth's orbit, it can give rise to meteor showers.
Professionals, however, are well aware of exceptions.
Comet Wirtanen fragmented in 1957 when it was just inside the orbit of Saturn. Conversely, in December 1680, the eponymous comet studied by Halley and Newton passed intact within 100,000km of the Sun.
Things took a more serious turn, as reported in 1990 by New Scientist.
The object named Chiron, discovered in 1977 as an asteroid orbiting between Jupiter and Neptune, had begun to "look like a gigantic comet".
Forget for a moment the stuff comets are made of - here, the very categories of astronomy were under attack.
An ontological debate ensued, mostly in private, but recently resulting in the public ejection of Pluto from the category of "planet". In this debate, the retention of a solar system cosmogony - including attachment to a primeval outer comet reservoir with links to the present (the Oort Cloud) - has been a significant feature.
Why do comets split?
Yet as far back as 1989, Carl Sagan and Nancy Druyan had remarked on the fact that 80 per cent of comets which split do so when they are far from the Sun.
In their book Comet, they wrote:
The gravitational tides of the Sun or unequal heating cannot be sole causes of the splitting of comets. We still do not know why comets split.
Stranger still, Dr Brian Marsden, for many years astronomy's Mr Orbital Elements extraordinaire, had noted in the 1960s that two comets, 1882 II and 1965 VIII, looked as if they had split apart near aphelion (their farthest distance from the Sun), beyond the orbit of Neptune and above the ecliptic plane. Has nothing progressed?
Contemporary authorities such as David C. Jewitt of the Institute for Astronomy, University of Hawaii, concede that still "most splitting events occur without obvious provocation and their cause is unknown". (See pdf, 1.2MB.)
This has not stopped cometologists devising ever more complex structures for comets to account for the more evident facts: some comets are conceived of as comprising an icy core well sealed in a rocky shell; others as having a refractory mantle for their orbital phase. But can the counter-intuitive nature of such theoretical elaborations equal some of the more counter-intuitive facts which recent observations have adduced, such as the production of X-rays?
Some commentators think that the standard narrative of comets has been allowed to grow in an ad hoc manner for too long.
The Institute of Electrical and Electronics Engineers (IEEE) has for many years had a Nuclear and Plasma Sciences Society subgroup, and has published papers since 1986 on the application of plasmas to the phenomena of astronomy. A 7th series is underway.
Countering the astronomical consensus, plasma physicists account for comet features in terms of a varying electrical potential experienced by the comet as it changes location within the electrical plasma field. This is the "solar wind" - centred on the Sun - which extends beyond Pluto, and which is modified by the magnetic and electrical contribution of the planets.
In this account, cometary comae and tails are the result of electrical arcing, analogous to electrical discharge machining, rather than sublimation.
The dual flashes of light observed when the Deep Impact spacecraft mission despatched a copper impactor into Comet Temple 1 were consistent with the expectations of plasma physicists. Scientists observed two flashes: the second flash was due to the impact, but the first flash was due to electrical discharge between the comet and the impactor, and resulted in failure of the on-board data collection and transmission systems.
A compilation of predictions about the Deep Impact encounter from the point of view of a plasma universe can be found here.
So a possible fragmentation of comet Holmes is not the only thing to look forward to. Some are asking if God if not after all a crude materialist, but a subtle electrician?
Follow the link above Larry's page for a comet-locating starmap. UK readers should crane their necks round midnight to the zenith, and adjust the gaze slightly north-east. With binoculars the fuzzy coma is clearly visible. ®
(*) Bootnote
Unlike the rest of science, the "order" of stellar magnitude is not computed to base 10, but to Pogson's Ratio of 2.512. To know exactly why, you would need to build a time machine, travel back to the ancient Greek period, and ask them how they could conceive of a sixth rate star, when you or I might make do with third or fourth rate ones.
Comment: Enjoy our latest Forum's Topic:
Speculations about the Comet 17P/Holmes
NASA
Thu, 15 Nov 2007 00:00 EST
NASA's Hubble Space Telescope has probed the bright core of Comet 17P/Holmes, which, to the delight of sky watchers, mysteriously brightened by nearly a millionfold in a 24-hour period beginning Oct. 23, 2007.
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| ©NASA |
| Image above: Images of Comet 17P/Holmes as seen from the ground (left) and the Hubble Space Telescope (right). Click image for enlargement. Credit: A. Dyer, Alberta, Canada (left); NASA/ESA/H. Weaver/The Johns Hopkins University Applied Physics Laboratory (right) |
Astronomers used Hubble's powerful resolution to study Comet Holmes' core for clues about how the comet brightened. The orbiting observatory's Wide Field Planetary Camera 2 (WFPC2) monitored the comet for several days, snapping images on Oct. 29, Oct. 31, and Nov. 4. Hubble's crisp "eye" can see objects as small as 33 miles (54 kilometers) across, providing the sharpest most detailed view yet of the source of the spectacular brightening.
The Hubble image at right, taken Nov. 4, shows the heart of the comet. The central portion of the image has been specially processed to highlight variations in the dust distribution near the nucleus. About twice as much dust along lies along the east-west direction (the horizontal direction) as along the north-south direction (the vertical direction), giving the comet a "bow tie" appearance.
The composite color image at left, taken Nov. 1 by an amateur astronomer, shows the complex structure of the entire coma, consisting of concentric shells of dust and a faint tail emanating from the comet's right side.
The nucleus-the small solid body that is the ultimate source of all the comet's activity-is still swaddled in bright dust, even 12 days after the spectacular outburst. "Most of what Hubble sees is sunlight scattered from microscopic particles," explained Hal Weaver of The Johns Hopkins University Applied Physics Laboratory in Laurel, Md., who led the Hubble investigation. "But we may finally be starting to detect the emergence of the nucleus itself in this final Hubble image."
Hubble first observed Comet 17P/Holmes on June 15, 1999, when there was virtually no dusty shroud around the nucleus. From that observation, astronomers deduced that the nucleus had a diameter of approximately 2.1 miles (3.4 kilometers), about the length of New York City's Central Park. Astronomers hope to use the new Hubble images to determine the size of the comet's nucleus to see how much of it was blasted away during the outburst.
Hubble's two earlier snapshots of Comet Holmes also showed some interesting features. On Oct. 29, the telescope spied three "spurs" of dust emanating from the nucleus, while the Hubble images taken on Oct. 31 revealed an outburst of dust just west of the nucleus.
The Hubble images, however, do not show any large fragments near the nucleus of Comet Holmes, unlike the case of Comet 73P/Schwassmann-Wachmann 3 (SW3). In the spring of 2006 Hubble observations revealed a multitude of "mini-comets" ejected by SW3 after the comet increased dramatically in brightness.
Ground-based images of Comet Holmes show a large, spherically symmetrical cloud of dust that is offset from the nucleus, suggesting that a large fragment did break off and subsequently disintegrated into tiny dust particles after moving away from the main nucleus.
Unfortunately, the huge amount of dust near the comet's nucleus and the comet's relatively large distance from Earth (149 million miles, or 1.6 astronomical units, for Holmes versus 9 million, or 0.1 astronomical unit for SW3), make detecting fragments near Holmes nearly impossible right now, unless the fragments are nearly as large as the nucleus itself.
The Hubble Comet Holmes observing team comprises H. Weaver and C. Lisse (The Johns Hopkins University Applied Physics Laboratory); P. Lamy (Laboratoire d'Astrophysique de Marseille, France); I. Toth (Konkoly Observatory, Hungary); M. Mutchler (Space Telescope Science Institute); W. Reach (California Institute of Technology); and J. Vaubaillon (California Institute of Technology).
The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. The Space Telescope Science Institute conducts Hubble science operations. The institute is operated for NASA by the Association of Universities for Research in Astronomy, Inc., Washington.
The Applied Physics Laboratory (APL) is a not-for-profit laboratory and division of The Johns Hopkins University. APL conducts research and development primarily for national security and for nondefense projects of national and global significance. APL is located midway between Baltimore and Washington, D.C., in Laurel, Md.
Scott Carney
Discover Magazine
Thu, 15 Nov 2007 07:44 EST
The serpent's tails coil together menacingly. A horn juts sharply from its head. The creature looks as if it might be swimming through a sea of stars. Or is it making its way up a sheer basalt cliff? For Bruce Masse, an environmental archaeologist at Los Alamos National Laboratory, there is no confusion as he looks at this ancient petroglyph, scratched into a rock by a Native American shaman. "You can't tell me that isn't a comet," he says.
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| ©Discover |
| The Fenambosy chevrons at the tip of Madagascar. Image courtesy of Dallas Abbott |
In Masse's interpretation, the petroglyph commemorates a comet that streaked across the sky just a few years before Europeans came to this area of New Mexico. But that event is a minor blip compared to what he is really after. Masse believes that he has uncovered evidence that a gigantic comet crashed into the Indian Ocean several thousand years ago and nearly wiped out all life on the planet. What's more, he thinks that clues about the catastrophe are hiding in plain sight, embedded in the creation stories of cultural groups around the world. His hypothesis depends on a major reinterpretation of many different mythologies and raises questions about how frequently major asteroid impacts occur. What scientists know about such collisions is based mainly on a limited survey of craters around the world and on the moon. Only 185 craters on Earth have been identified, and almost all are on dry land, leaving largely unexamined the 70 percent of the planet covered by water. Even among those on dry land, many of the craters have been recognized only recently. It is possible that Earth has been a target of more meteors and comets than scientists have suspected.
Masse's epiphany came while poring over Hawaiian oral histories regarding the goddess Pele and wondering what they might reveal about the lava flows that episodically destroy human settlements and create new tracts of land. He reasoned that even though the stories are often clouded by exaggerations and mystical explanations, many may refer to actual incidents. He tested his hypothesis by cross-checking carbon-14 ages for the lava flows against dates included in royal Hawaiian genealogies. The result: Several flows matched up with the specific reigns associated with them in the oral histories. Other myths, Masse theorizes, hold similar clues.
Masse's biggest idea is that some 5,000 years ago, a 3-mile-wide ball of rock and ice swung around the sun and smashed into the ocean off the coast of Madagascar. The ensuing cataclysm sent a series of 600-foot-high tsunamis crashing against the world's coastlines and injected plumes of superheated water vapor and aerosol particulates into the atmosphere. Within hours, the infusion of heat and moisture blasted its way into jet streams and spawned superhurricanes that pummeled the other side of the planet. For about a week, material ejected into the atmosphere plunged the world into darkness. All told, up to 80 percent of the world's population may have perished, making it the single most lethal event in history.
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Up to 80 percent of the world's population may have perished.
Why, then, don't we know about it? Masse contends that we do. Almost every culture has a legend about a great flood, and - with a little reading between the lines - many of them mention something like a comet on a collision course with Earth just before the disaster. The Bible describes a deluge for 40 days and 40 nights that created a flood so great that Noah was stuck in his ark for two weeks until the water subsided. In the Gilgamesh Epic, the hero of Mesopotamia saw a pillar of black smoke on the horizon before the sky went dark for a week. Afterward, a cyclone pummeled the Fertile Crescent and caused a massive flood. Myths recounted in indigenous South American cultures also tell of a great flood.
"These stories are all exactly what you would expect from the survivors of a celestial impact," Masse says, leafing through 2,000-year-old drawings by Chinese astronomers that show comets of all shapes and sizes. "When a comet rounds the sun, oftentimes its tail is still being blown forward by the solar winds so that it actually precedes it. That is why so many descriptions of comets in mythology mention that they are wearing horns." In India, he notes, a celestial fish described as "bright as a moonbeam," with a horn on its head, warned of an epic flood that brought on a new age of man.
Among 175 flood myths, Masse found two of particular interest. A Hindu myth describes an alignment of the five bright planets that has happened only once in the last 5,000 years, according to computer simulations, and a Chinese story mentions that the great flood occurred at the end of the reign of Empress Nu Wa. Cross-checking historical records with astronomical data, Masse came up with a date for his event: May 10, 2807 B.C.
On its own, the mythological evidence is weak, as even Masse recognizes. "Mythology can help us hypothesize about events that might have occurred," he says, "but to prove the reality of them, we have to go beyond myths and search for physical evidence."
In 2004, at a conference of geologists, astronomers, and archaeologists, Masse outlined his evidence for a world-ravaging impact in the middle of the Indian Ocean. Ted Bryant, a geomorphologist at the University of Wollongong in New South Wales, Australia, was intrigued and enlisted the help of Dallas Abbott, an assistant professor at the Lamont-Doherty Earth Observatory at Columbia University. In 2005, they formed the Holocene Impact Working Group (referring to the geological period covering the last 11,000 years) to seek out the geological signatures of a megatsunami. If a 600-foot-high wave ravages a coastline, it should leave a lot of debris behind. In the case of waves generated by asteroid impacts, the debris they leave in their wake is believed to form gigantic, wedge-shaped sandy structures - known as chevrons - that are sometimes packed with deep- oceanic microfossils dredged up by the tsunami.
When Abbott began searching satellite images on Google Earth, she saw dozens of chevrons along shorelines and inland in Africa and Asia. The shape and size of these chevrons suggest that they might have been formed by waves emanating from the impact of a comet slamming into the deep ocean off Madagascar. "The chevrons in Madagascar associated with the crater were filled with melted microfossils from the bottom of the ocean. There is no explanation for their presence other than a cosmic impact," she says. "People are going to have to start taking this theory a lot more seriously." The next step is to perform carbon-14 dating on the fossils to see if they are indeed 5,000 years old.
Meanwhile, Bryant contends that chevrons found (pdf) 4 miles inland from the shore of Madagascar were formed by a wave that traveled 25 miles along the coast, moving almost parallel to the shoreline. "Neither erosion nor any other terrestrial process could have caused these formations. The biggest marine landslide ever recorded happened 7,200 years ago off the coast of Norway, and there was a tsunami, but it was a far cry from leaving deposits 200 meters above sea level," Bryant says.
Not everyone is convinced, to say the least. "I don't believe the evidence of a crater off Madagascar, and the impetus is on Abbott to prove it," says Jay Melosh, an impact expert at the University of Arizona and an outspoken critic of the theory. To make a case for the impact, Melosh says, Abbott "should be finding layers of glassy droplets and fused rock in sea-core samples, the sorts of things we find at all other similar impact sites."
On the other hand, a lot remains unknown about impacts. As recently as 60 years ago, some geologists believed that the Barringer Meteor Crater in Arizona - now considered the prototypical impact scar - was caused by a volcanic explosion, and they regarded impacts as a minor if not inconsequential influence on Earth's history. Just 25 years ago, Luis and Walter Alvarez raised eyebrows with their idea that an asteroid collision helped kill off the dinosaurs. So Abbott continues to hunt for evidence that will clinch the idea that Noah's flood was yet another example of extraterrestrial meddling. "It is still up to us to prove it, but if we have unequivocal impact ejecta," she says, Melosh "is going to have to eat his words."
Meteor theory's impact: Cosmic blows could occur more frequently
By Sandra Blakeslee
The New York Times
Tue, 14 Nov 2006 12:00 EST
Most astronomers doubt that any large comets or asteroids have crashed into the Earth in the past 10,000 years. But the self-described "band of misfits" that make up the two-year-old Holocene Impact Working Group say astronomers simply have not known how or where to look for evidence.
Scientists in the working group say the evidence for such impacts during the past 10,000 years, known as the Holocene epoch, is strong enough to overturn current estimates of how often the Earth suffers a violent impact on the order of a 10-megaton explosion. Instead of once in 500,000 to 1 million years, as astronomers now calculate, catastrophic impacts could happen every few thousand years.
At the southern end of Madagascar lie four enormous wedge-shaped sediment deposits, called chevrons, that are composed of material from the ocean floor. Each covers more than 100 square kilometers with sediment hundreds of meters deep.
On close inspection, the chevron deposits contain deep-ocean microfossils that are fused with a medley of metals typically formed by cosmic impacts. And all of them point in the same direction - toward the middle of the Indian Ocean where a newly discovered crater, 29 kilometers, or 18 miles, in diameter, lies 3,800 meters, or 12,500 feet, below the surface.
The explanation is obvious to some scientists. A large asteroid or comet, the kind that could kill a quarter of the world's population, smashed into the Indian Ocean 4,800 years ago, producing a tsunami at least 183 meters thigh, about 13 times as big as the one that inundated Indonesia nearly two years ago. The wave carried the huge deposits of sediment to land.
Most astronomers doubt that any large comets or asteroids have crashed into the Earth in the past 10,000 years. But the self-described "band of misfits" that make up the two-year-old Holocene Impact Working Group say astronomers simply have not known how or where to look for evidence.
Scientists in the working group say the evidence for such impacts during the past 10,000 years, known as the Holocene epoch, is strong enough to overturn current estimates of how often the Earth suffers a violent impact on the order of a 10-megaton explosion. Instead of once in 500,000 to 1 million years, as astronomers now calculate, catastrophic impacts could happen every few thousand years.
The researchers, who formed the working group after finding one another through an international conference, are based in the United States, Australia, Russia, France and Ireland. They are established experts in geology, geophysics, geomorphology, tsunamis, tree rings, soil science and archaeology, including the structural analysis of myth. Their efforts are just getting under way, but they will present some of their work at the American Geophysical Union meeting in December in San Francisco.
This year the group started using Google Earth, a free source of satellite images, to search the globe for chevrons, which they interpret as evidence of past giant tsunamis. Scores of such sites have turned up in Australia, Africa, Europe and the United States.
When the chevrons all point in the same direction to open water, Dallas Abbott, an adjunct research scientist at Lamont-Doherty Earth Observatory in Palisades, New York, uses a different satellite technology to look for oceanic craters. With increasing frequency, she finds them, including an especially large one dating back 4,800 years.
So far, astronomers are skeptical but willing to look at the evidence, said David Morrison, a leading authority on asteroids and comets at the NASA Ames Research Center in California.
Surveys show that as many as 185 large asteroids or comets hit the Earth in the far-distant past, although most of the craters are on land. No one has spent much time looking for craters in the deep ocean, Morrison said, assuming that young ones do not exist and that old ones would be filled with sediment.
Astronomers monitor every small space object with an orbit close to the Earth. "We know what's out there, when they return, how close they come," Morrison said. Given their observations, "there is no reason to think we have had major hits in the last 10,000 years," he continued, adding, "But if Dallas is right and they find 10 such events, we'll have a real contradiction on our hands."
Peter Bobrowski, a researcher of natural hazards at the Geological Survey of Canada, said that "chevrons are fantastic features" but do not prove that megatsunamis are real. There are other interpretations for how chevrons are formed, Bobrowski said, and it is up to the working group to prove its claims.
Ted Bryant, a geomorphologist at the University of Wollongong in Australia, was the first person to recognize the palm prints of megatsunamis. Large tsunamis of nine meters or more are caused by volcanoes, earthquakes and submarine landslides, he said, and their deposits have different features.
Deposits from megatsunamis contain unusual rocks with marine oyster shells, which cannot be explained by wind erosion, storm waves, volcanoes or other natural processes, Bryant said.
"We're not talking about any tsunami you're ever seen," Bryant said. "Aceh was a dimple. No tsunami in the modern world could have made these features. End-of-the-world movies do not capture the size of these waves."
For example, Bryant identified two chevrons found more than six kilometers inland near Carpentaria in north- central Australia. Both point north. When Abbott visited a year ago, he asked her to find the craters.
To locate craters, Abbott uses sea-surface altimetry data. Satellites scan the ocean surface and log the exact height of it. Underwater mountain ranges, trenches and holes in the ground disturb the Earth's gravitational field, causing sea-surface heights to vary by milimeters. Within 24 hours of searching the shallow water north of the two chevrons, Abbott found two craters.
"We think these two craters are 1,200 years old," Abbott said. The chevrons are well-preserved and date to about the same time.
Abbott and her colleagues have located chevrons in the Caribbean, Scotland, Vietnam and North Korea, and several in the North Sea.
But Madagascar provides the smoking gun for geologically recent impacts. In August, Abbott, Bryant and Slava Gusiakov, from the Novosibirsk Tsunami Laboratory in Russia, visited the four huge chevrons to scoop up samples.
Last month, Dee Breger, director of microscopy at Drexel University in Philadelphia, looked at the samples under a scanning electron microscope and found benthic foraminifera, tiny fossils from the ocean floor, sprinkled throughout. Her close-ups revealed splashes of iron, nickel and chrome fused to the fossils.
When a chondritic meteor, the most common kind, vaporizes upon impact in the ocean, those three metals are formed in the same relative proportions as seen in the microfossils, Abbott said.
Breger said the microfossils appear to have melded with the condensing metals as both were lofted up out of the sea and carried long distances.
About 1400 kilometers southeast from the Madagascar chevrons, in deep ocean, is Burckle Crater, which Abbott discovered last year. Burckle Crater has not been dated, but Abbott estimates that it is 4,500 to 5,000 years old.
It would be a great help to the cause if the National Science Foundation sent a ship equipped with modern acoustic equipment to take a closer look at Burckle, said William Ryan, a marine geologist at the Lamont-Doherty observatory. "If it had clear impact features, the nonbelievers would believe," he said.
But they might have more trouble believing one of the scientists, Bruce Masse, an environmental archaeologist at the Los Alamos National Laboratory in New Mexico. He thinks he can say precisely when the comet fell: on the morning of May 10, 2807 B.C.
Masse analyzed 175 flood myths from around the world and tried to relate them to known and accurately dated natural events like solar eclipses and volcanic eruptions. Among other evidence, he said, 14 flood myths specifically mention a full solar eclipse, which could have been the one that occurred in May 2807 B.C.
Half the myths talk of a torrential downpour, Masse said. A third tells of a tsunami. Worldwide, they describe hurricane-force winds and darkness during the storm. All of these could come from a megatsunami.
Of course, extraordinary claims require extraordinary proof, Masse said, "and we're not there yet."
The Times of India
Tue, 20 Nov 2007 14:35 EST
London: A new study by scientists suggests that asteroids which are deflected on a collision course with Earth are likely to return for another potential clash.
According to the study presented to the US House Science and Technology Committee last week, methods like nuclear explosions might deflect an asteroid temporarily, but it does not guarantee safety next time its orbit brings it close.
Rusty Schweickart, who heads an asteroid research group, told the committee that the effects of powerful blasts are hard to predict, especially if the Earth's gravitational pull acts on the object.
"An asteroid could pass through one of the 'keyholes' that would nudge it back onto a collision course with Earth," Schweickart said. "So once diverted, it might need to be steered past Earth to prevent this," he added.
At the same hearing, members attacked NASA for ignoring smaller asteroids.
Krzysztof Czart
Astronomia.pl
Thu, 22 Nov 2007 09:41 EST
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| ©Nicolaus Copernicus University in Toruń. |
| Sequence of images of Comet 17P/Holmes obtained with the TSC 60/90 telescope in the V filter. They show the increase in the comet's envelope size. The colours are chosen here in order to best show the cometary nucleus (the bright point in the centre) and matter moving away from the nucleus (to the right of the nucleus). |
Comet 17P/Holmes has been intriguing astronomers since the end of October, when its sudden outburst in brightness, the biggest in the history of comet research, was observed. Scientists from Nicolaus Copernicus University in Torun in Poland have published a series of images illustrating the evolution of the comet.
Astronomers from the Torun Centre for Astronomy of Nicolaus Copernicus University in Torun (Poland) pointed their 0.9 m optical telescope at the comet. At optical wavelengths, they obtained many images. The first images were obtained on 26th October, three days after the outburst. The following images were taken on 2nd, 8th, 10th November and finally on 15th November.
By composing these photos into a sequence of images using the same scale in each picture, the increase in the size of the comet's envelope can be seen. The comet's envelope on November 15th was seven times bigger than that of 26th October. On the website of the Torun Centre for Astronomy a movie presenting the comet, obtained with 0.6 m telescope, is available.
17P/Holmes is now 1.6 astronomical units (nearly 250 million kilometers) from the Earth. The comet-Earth distance is increasing. The next return of Comet Holmes is expected in about 7 years' time.
"We have been doing observations to detect fast changes in brightness of the nucleus, over a range of minutes or even seconds. Our data do not show changes of brightess on this time scale during one night session." said Ernest Swierczynski, student and one of the observers of the comet from the Nicolaus Copernicus University.
"From experience with similar comets, astronomers know that after a rapid outburst in brightness during about 2.5 days, a comet should then return back to its previous brightness in about 20-30 days. 17P/Holmes does not behave according to this rule, it is still bright, even though it is almost one month since the outburst (the comet's outburst happened around 23th October)." said Dr Maciej Mikolajewski from Nicolaus Copernicus University.
The comet can be seen in Perseus, near the brightest star of this constellation. 17P/Holmes' brightness was 3 magnitudes on 15th November. It is recommended to watch it with binoculars on a non-cloudy night.
The Torun Centre for Astronomy is an astronomical observatory of Nicolaus Copernicus University, located 10 km north of Torun city in central Poland. Among its telescopes are 0.6 m and 0.9 m optical telescopes and 15 m and 32 m radiotelescopes. Nicolaus Copernicus University in Torun is one of the biggest universities in Poland, with about 40,000 students.
More information:
* Torun Centre for Astronomy - images of the comet
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| ©Nicolaus Copernicus University in Toruń. |
| Sequence
of images of Comet 17P/Holmes obtained with the TSC 60/90 telescope in
the V filter. They show the increase in the comet's envelope size.
Exposition times varied from 8 to 300 seconds. |
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| ©Nicolaus Copernicus University in Toruń. |
| Photo of Comet 17P/Holmes taken on 2.11.2007 with the TSC 60/90 telescope (0.9 m diameter). The image is created from photos in the B, V and R filters. |
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| ©Nicolaus Copernicus University in Toruń. |
| Image of Comet 17P/Holmes taken in the V filter on 10.11.2007 with the TSC 60/90 telescope (0.9 m diameter). The colour palette was chosen to emphasize the cometary nucleus (the bright point in the centre) and the comet's envelope. |
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| ©Nicolaus Copernicus University in Toruń. |
| Image of Comet 17P/Holmes taken in V filter on 10.11.2007 with the TSC 60/90 telescope (0.9 m diameter). |
Translation: Krzysztof Czart, Boud Roukema
Sira Habibu
The Star
Sat, 24 Nov 2007 16:31 EST
The mystery "blast" that rocked Kuala Terengganu, Dungun and Marang in Terengganu for several seconds on Friday turned out to be sonic boom from the newly-acquired state-of-the-art Sukhoi fighter jet.
Two of the fighter jets were involved in a non-combatant training in preparation for the Langkawi International Maritime and Aerospace (LIMA) air show.
Royal Malaysian Air Force (RMAF) public relations officer Maj Zulkiflee Abdul Latiff said the fighter jets travelled at supersonic speed, emitting loud sonic booms.
"We hope the people in Terengganu do not panic upon hearing the sound,'' he said.
RMAF cleared the air following reports in the media that the "mysterious blast" shook high-rise buildings, causing some dwellers to run out of their homes.
The Star office in Kuala Terengganu was inundated with calls on Friday from people who wanted to know the cause of the 4.10pm "blast".
Zulkiflee, when contacted, said air force pilots need to undergo training exercises, not only for the air show but also for defence purposes.
Malaysia acquired six Sukhoi fighter jets from Russia recently.
"The fighter jets were flying more than 10,000m above sea level,'' he said, adding that the training exercise commenced on Friday.
"The exercises are being carried out in the interest of the nation,'' he said.
Jan Pomierny
SOHO
Fri, 30 Nov 2007 04:44 EST
Michal Kusiak, a student of astronomy at Jagiellonian University in Krakow and an editor of Astronomia.pl has discovered a new comet. This young astronomy enthusiast found the object in images sent back to Earth by the SOHO Solar Observatory. Information on the discovery has been already published on a Web Site of the British Astronomical Association.
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| ©SOHO |
| Comet belonging to the Kreutz family |
Michal Kusiak discovered the comet on 24th November. Soon after his discovery was confirmed by an observer from China, Bo Zhou. Currently the object awaits the confirmation of its orbit by the coordinator of the SOHO Comets Programme, Karl Battams. The official confirmation of the discovery is expected any day soon.
Kusiak's comet belongs o the Kreutz family, that is, to a formation of comets whose perihelion (the greatest distance of the orbit away from the Sun) is situated in the vicinity of the photosphere of our star. Such a small distance from the Sun results in total evaporation of almost all objects belonging to the family.
Michal Kusiak discovered the previously unknown object in images taken by the SOHO Solar Observatory. In orbit since 1995, the instrument has provided loads of data for heliophysicists, yet also astronomers have benefited from its capabilities, with more than 1300 comet discoveries so far.
Comets are spotted quite often in images taken by the LASCO Coronograph, a component of the SOHO. They are usually small objects and their number is so great that also amateur astronomers have been involved in their discoveries. These astronomy enthusiasts analyse images and report any 'suspected' objects. Polish amateur-astronomers are the strongest group in the project. Last year it was the Polish student who became famous as regards comet discoveries. Arkadiusz Kubczak, from Piotrkow Trybunalski, discovered the thousandth SOHO comet belonging to the Kreutz family.
Michal Kusiak comes from Zywiec and is currently a student of astronomy at Jagiellonian University in Krakow. He has participated in the SOHO Comets Projects for three years. The comet discovered by the student is his first discovery, yet he also contributed to the discoveries made by Arkadiusz Kubczak, whom he introduced to the comet-search project.
In order to participate in the project one needs to have access to a computer and a permanent connection to the Internet. The person must also be very patient and commit him/herself to conducting systematic analyses.
More information:
* Official SOHO Comets Project
[ Author: Astronomia.pl - Jan Pomierny ]
[ Translation: Marek Łukasik ]
Original Polish version: Nowa polska kometa
Trevor Davis
Oregon Daily Emerald
Sat, 01 Dec 2007 15:54 EST
A group of University scientists have proposed a controversial new theory about the end of the last ice age
For the record, they're not crazy.
But they do admit their theory is out there.
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| ©Ryan Heidt |
| Two University researchers theorize that a comet may have hit North America about 13,000 years ago, causing an end to several species of animals near the end of the last ice age. |
University researchers Douglas Kennett and Jon Erlandson are part of a group of scientists proposing that a comet or asteroid hit North America about 13,000 years ago - near the end of the last ice age - and contributed to major events in the continent's history, including the die-off of horses, mammoths and other large mammals around the same time.
The theory is turning decades of research on its head. The die-off of animals is usually explained by humans over-hunting the animals or an abrupt climate change.
"There are people who have made their whole careers on human hunters causing the extinction of animals," Erlandson said. "They've been writing about it for 40 years. There are some people who are not likely to be really happy with this theory."
Researchers say the comet - a ball of ice, rock and dust from outer space - hit the Laurentide ice sheet in Canada.
"It wouldn't have left a crater because it would have exploded and sent a shower of debris and chunks of ice," said Erlandson, adding the impact would have been ice on ice.
Heat from impact may have sparked fires across the continent, and the melting of the ice sheet may have caused flooding. Researchers say the comet may have contributed to human population reduction and localized animal extinction.
Researchers say the comet may have helped cause a cold climate period that lasted for about 1,300 years, called the Younger Dryas, and may have wiped out or fragmented the prehistoric Clovis tribe.
A carbon-rich black layer found at more than 50 sites around North America is evidence for the impact, according to the article published in the Proceedings of the National Academy of Sciences. The layer contains iridium, carbon spherules and fullerenes with helium 3. Evidence of mammoths and other animals, along with early human hunters, are found beneath the black mat, but are missing within or above the strip.
More evidence is found in the Carolina Bays, which are depressions from New Jersey to Florida. Erlandson says the depressions point toward the ice sheet, possibly a result of the comet.
The theory, which is known as the "YDB Comet Theory," was first proposed by University of California at Santa Barbara paleoceanographer James Kennett, Douglas Kennett's father, Richard Firestone of the Lawrence Berkeley National Laboratory and Arizona researcher Allen West. Douglas Kennett often collaborates with his father.
The theory has generated its share of naysayers.
University of Nevada at Reno anthropologist Gary Haynes says he and archeologist Stuart Fiedel object to the comet theory. In an e-mail, he listed reasons for the skepticism.
"In spite of what the comet theorists claim, Paleo-Indians thrive after the time of the supposed comet impact," Haynes said. "Clovis culture is transformed into Folsom, Dalton and Eastern U.S. variants, and all of these are much more numerous than Clovis, suggesting a human population increase, not collapse."
Graduate student Brendan Culleton, who is involved in the research, admits it's both scary and exciting to be involved in the studies.
"It's a crazy idea," Culleton said. "You should think this is insane when you hear about this."
Science and Nature magazines declined to publish the article.
"If the theory's true, it's the biggest story of the year - maybe the decade," Erlandson said.
Douglas Kennett, who is in Spain on sabbatical, said in an e-mail that there are and will be doubters.
"This is natural given the magnitude of this hypothesis and its potential significance in the history of our planet," Douglas Kennett said. "The scale of inquiry is also massive and we have just started to scratch the surface in terms of this event and its consequences."
Even the researchers themselves say the theory needs more work.
"I'm not 100 percent convinced, but there's tantalizing evidence," Erlandson said. "There's a lot more work that needs to be done to confirm this."
Erlandson said it could take a decade worth of research to prove the theory.
Douglas Kennett said the group needs to replicate some of its findings at existing localities with more refined techniques, and said they need to locate additional study sites both in the northern and southern hemispheres to determine if the effects are global beyond the effects of the Younger Dryas cold interval.
Erlandson said he will continue to have an open mind when it comes to the theory.
"Science moves on," he said. "You have to be driven by data."
Thomas F. King
About.com: Archaeology
Thu, 06 Dec 2007 15:45 EST
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| ©Gustave Moreau (1826-1898) |
| The Fall of Phaethon |
Italian geologist Luigi Piccardi and archaeologist Bruce Masse recently teamed to co-edit Myth and Geology (2007-Geological Society of London Special Publication 273), the first professional textbook on the nascent subdiscipline of geomythology. Geomythology pairs geological evidence of catastrophic events and reports of such events encoded into the mythological lexicon of ancient societies.
In the following contributed essay, archaeologist Thomas F. King discusses Masse's chapter "The archaeology and anthropology of Quaternary period cosmic impact," in the 2007 Springer Press book Comet/Asteroid Impacts and Human Society: An Interdisciplinary Approach, edited by geologist Peter Bobrowsky and astronomer Hans Rickman. The chapter uses geomythology to investigate the possible catastrophic comet or asteroid strike which may have led to disaster legends which have come down to us today.
Do Global Myths Reflect an Ancient Disaster?
Exploring the Nature of Myth
Scientists who model the probabilities of comet and asteroid impacts on Earth estimate that a really devastating impact--capable of killing more than a billion people (at today's standards) and wiping out civilization as we know it--has happened only every million years or so. Archaeologist Bruce Masse thinks such impacts may have happened more frequently, or at least more recently than believed by the astrophysical community. If he's right, the danger posed by near earth objects (NEOs) is possibly greater than we've thought. Masse's ideas are detailed in "The archaeology and anthropology of Quaternary period cosmic impact," a chapter in the 2007 Springer Press book Comet/Asteroid Impacts and Human Society: An Interdisciplinary Approach, edited by geologist Peter Bobrowsky and astronomer Hans Rickman.
Bruce Masse's Passion
Masse, like many of today's archaeologists, isn't based in a museum or university, but works for a government agency--in his case, Los Alamos National Laboratory in New Mexico. His day job involves managing the more than 2,000 archaeological sites on Laboratory lands--making sure they're not damaged by the Laboratory's operations. But his passion over the last few decades has been studying the archaeological and anthropological record of celestial phenomena and earthly catastrophes. In the Springer chapter he presents a startling picture of how such events may have been linked during the course of the Quaternary period--the last 2.6 million years.
Masse became interested in how cosmic phenomena like eclipses and comet encounters were perceived by ancient people while doing research in Hawaii in the late 1980s. The genealogical traditions of Hawaiian royalty, he found, were full of descriptions of things that happened in the sky--comet encounters, meteor showers, eclipses, supernovae. Some of the same events are described in historic European, Chinese, and Muslim records. Masse was able to plot dozens of precise matches between Hawaiian tradition and the astronomical observations of literate observers elsewhere in the world. The more he looked at mythology, the less mythical it appeared, where celestial phenomena were concerned.
Encoding a Cosmic Event
When he thought objectively about how myths come to be, and who creates and sustains them, it made sense that they would encode impressive and hard-to-account-for events. "A myth," he says, "is an analogical story created by highly skilled and trained cultural knowledge specialists (such as priests or historians) using supernatural images in order to explain otherwise inexplicable natural events or processes." The priest doesn't just invent his story of the sun being eaten by a giant dog; he comes up with it as a means of explaining an eclipse that has his people scared out of their wits.
Masse began examining both the mythology and the archaeology of areas around the sites where asteroids or comets were known or suspected to have fallen to earth during the Quaternary, and especially during the last 11,000 years, known as the Holocene. Science is aware of at least twenty-seven known Quaternary impact sites, marked by craters and often the remnants of meteoritic iron and melted stone. Other impacts are known from the presence of glassy melts and tektites created by an impact or explosion in the atmosphere (an airburst). Virtually all are on land, where scientists have been able to record, study, and date them using radiocarbon age determination and other geophysical methods. Since the Earth's land masses make up only about a third of the planet's surface, it follows that in the last 2.6 million years there have been roughly 75 comet/asteroid strikes potentially big enough to leave physical signs on the ground, with even larger numbers striking the oceans. Few of these were big enough to have wiped out a civilization had one existed in the neighborhood, but each one could have killed a lot of our ancestors.
Archaeological Traces of Holocene Impacts
We have no myths extending back 2.6 million years, of course, but myths have survived in some cultures for hundreds and even thousands of years (Consider Jason and the Argonauts). So it isn't outlandish to think that Holocene impacts might be reflected in the myths of nearby peoples. They might also have left archaeological traces. Masse began to compile the results of ethnographic, oral historical, and archaeological studies in areas surrounding known and probable Holocene impact sites, and he found evidence suggesting that such traces do exist. At Saaremaa Island in Estonia, for example, where a meteor is known to have struck sometime between about 6400 and 400 BC, myths speak of a god that flew to the island along the track the meteor is calculated to have taken, and of a time when the island burned.
Archaeological and paleobotanical evidence suggests a multi-generational break in human occupation and farming in the area beginning sometime between 800 and 400 BC, and a village about 20 km from the impact crater shows evidence of having burned at about the same time. At Campo de Cielo in Argentina, a crater field littered with small meteorites, dated to between 2200 and 2700 BC, myths recorded in the early 20th century reportedly tell of an impact by a piece of the sun. In most cases where impacts are well documented, however, no pertinent archaeological or ethnographic studies have been reported, and in most places where myths or archaeology suggest the possibility of cataclysms, no obvious craters or tektite fields have been yet documented by geophysicists.
But if myths can codify records of celestial phenomena, as Masse's
Hawaiian work shows, then a consistent regional pattern of mythic
accounts describing catastrophe from the sky might suggest the
existence of an impact event that has not yet been identified
geophysically, and indicate fruitful locations for geophysical
investigation. To pursue this possibility, Masse and his
geologically-trained brother Michael undertook a comprehensive analysis
(reported in Myth and Geology) of over four thousand myths
recorded throughout South America east of the Andes, conveniently
gathered into a database by UCLA. What particularly stood out in the
analysis were 284 myths describing cataclysms that, in the view of
those reciting the story, caused more or less universal death,
triggering a new creation of humanity.
Destruction Myths
The Masse brothers found that the destruction myths almost always described one or more of four phenomena--a great flood, a world fire, the falling of the sky, and a great darkness. When two or more of these phenomena were described by myths in the same culture, they fell into a consistent sequence. At least in the Gran Chaco, the flood was earliest, then the fire, and more recently the falling sky and the darkness. Their analysis suggested that the last two events--falling sky and great darkness--reflect aspects of volcanic eruptions. The world fire and great flood myths are different.
Some of the world fire stories quite explicitly describe the impacts of celestial objects. The Toba-Pilaga of the Gran Chaco, for example, speak of a time when fragments of the moon fell to earth, igniting a fire that incinerated the whole world, burning people alive and leaving corpses floating in the lagoons. Evidence suggests that this event may be associated with the Campo del Cielo impact crater field in northern Argentina dated around 4500 years ago. In the highlands of Brazil there are stories of Sun and Moon fighting for a red feather ornament, which fell to earth together with hot coals that started a world fire so hot that even the sand burned. The UCLA database contains a number of such stories.
Do these myths reflect one or more cataclysmic fires caused by cosmic impacts that devastated eastern South America? Masse thinks it likely enough to justify more research.
There Was a Great Flood....
But the stories of the great flood give even more cause for thought. In South America it is the most commonly reported worldwide catastrophe. Masse found it in 171 myths among groups scattered from Tierra del Fuego in the south to the far northwest part of the continent. It is consistently the earliest disaster, always reported prior to the world fire, falling sky and darkness. In the vast majority of cases only a single great flood is described, which Masse thinks makes it unlikely that it represents recollection of local or regional flooding. And South America isn't the only place it occurs.
Of course, the biblical story of Noah's flood is well known, as is the related Mesopotamian story of Gilgamesh and the flood. Many explanations have been advanced for these flood stories and others in the Middle East, most involving regional events like the sudden flooding of the Black Sea in the early Holocene. Back in 1994 Alexander and Edith Tollmann foreshadowed Masse's research by proposing a cosmic impact as the cause of a worldwide flood in about 9600 BC. The Tollmann's proposal has been widely rejected by scholars, and Masse is very critical of it, saying that the Tollmanns "mix the Biblical creation myth with flood myths, and make generalizations not warranted by the myths they use." Masse emphasizes the need to apply to myth research the same rigorous standards applied to other kinds of scientific study.
Attempting to apply such standards, Masse examined a worldwide sample of flood myths in 175 different cultures all over the world (most gathered and reported by noted anthropologist Sir James George Frazer in the early 1900s)--representing about 15% of the "great flood" myths that have been published in English. He hypothesized that if these myths reflected a single worldwide cataclysm, then the information encoded in them--the environmental aspects of the flood that they describe--should form a pattern across cultures that is consistent with a single event. Collectively they should create a plausible description of the event as experienced in different parts of the world, and that description should be consistent with archaeological and geophysical data. He analyzed his 175 myths with this hypothesis in mind, and found that "only a globally catastrophic deep-water oceanic comet impact can account for all the environmental information encoded in the corpus of worldwide flood myths."
Tsunamis and Rainstorms
The majority of the myths describe a torrential, long-duration rainstorm, in many cases accompanied by a huge tsunami. The water is often described as hot, sometimes coming as hot ocean swells, sometimes as burning rain. The described durations of the flood storm in the various myths, when plotted, form a bell-shaped curve with the great majority clustering between four and ten days. Tsunamis are described as extending between 15 and 100 km inland. Survivors typically find refuge in places between 150 and 300 meters above sea level.
Supernatural creatures are associated with the flood storm in nearly half the cases Masse studied. Typical are giant snakes or water serpents, giant birds, giant horned snakes, a fallen angel, a star with fiery tail, a tongue of fire, and similar elongated things in or from the sky. Looking in detail at descriptions in the mythology, particularly those of the Indian subcontinent, Masse sees a close resemblance to the naked-eye appearance of a near-earth post-perihelion comet.
Sixteen of the myths Masse examined describe when the flood storm occurred in terms of seasonal indicators. Fourteen myths are from Northern Hemisphere groups, and place the event in the spring. The one from the Southern Hemisphere places it in the fall--that is, spring north of the equator. Seven stories give the time in terms of lunar phase--six at the time of the full Moon, another two days later. Stories from Africa and South America say it happened at the time of a lunar eclipse, which can only occur when the Moon is full. A 4th century BC Babylonian account specifies a full Moon in late April or early May.
Chinese sources recount how the cosmic monster Gong Gong knocked over a pillar of heaven and caused flooding toward the end of the reign of Empress Nu Wa, around 2810 BC. The 3rd century BC Egyptian historian Manetho says there was an "immense disaster" (but doesn't say what kind) during the reign of the pharaoh Semerkhet, around 2800 BC. The tomb of Semerkhet's successor, Qa'a, was built of poorly dried mud bricks and timbers showing unusual decay; the following pharaohs of the second dynasty relocated the royal cemetery to higher ground. Masse's analysis of astrological references in multiple myths from the Middle East, India and China--describing planetary conjunctions associated with the flood storm, whose actual times of occurrence can be reconstructed using contemporary astronomy software--leads him to conclude that the event happened on or about May 10, 2807 BC.
What was it that happened? Masse thinks the myths provide clues to that, too. For one thing, they report massive rain, falling for days at a time. This turns out to be exactly what can be expected if a large comet plunged into the deep ocean--it would loft nearly ten times its mass of water into the upper atmosphere, where it would spread widely and then fall, taking days to empty the skies. A large impact in the ocean would also cause gigantic tsunamis, as many of the myths report. In India, for example, Tamil myths tell of the sea rushing 100 km inland, a hundred meters deep.
Plotting Mythic Events: The Burckle Crater
Plotting the distribution of great flood myths together with specific reported phenomena like directions from which great winds blew or tsunamis came, Masse finds that the most efficient way to account for them is by positing a very large comet impact in the central or southern Indian Ocean. This might not account very well for flood myths in the Americas, but Masse thinks that flooding there could have resulted from partial disintegration of the incoming comet, with two or more pieces falling on different parts of the earth over a period of hours or days. Some of the myths speak of multiple events happening in close succession. But the really big impact, he thinks, the most lethal of the bunch, occurred somewhere south of Madagascar.
Where, it turns out, there is a possible impact crater on the sea floor 1500 kilometers southeast of Madagascar. Named Burckle Crater and discovered only recently by Masse's colleague Dallas Abbott from Lamont Doherty Earth Observatory, it is a little under 30 km in diameter and is visible on bathymetric maps. Stratigraphic cores taken near there suggest that it is an impact crater, but are not definitive. The Burckle Crater needs more study, but it is 3800 meters deep, so it's not an easy place to explore. More readily accessible is the southern coast of Madagascar where recently studied chevron-shaped dune deposits of potential tsunamic origin may be indicative of giant waves more than 200 meters in height. Masse and Abbott have joined together with more than 25 other scientists to form the "Holocene Impact Working Group," to better explore Burckle Crater, Madagascar, and other locations bearing potential Holocene physical evidence of impact.
If Masse is right, a comet impact big enough to have devastating effects on human civilization occurred in 2807 BC--a bit under 5,000 years ago. Other smaller impacts and airbursts have happened since then--the most recent being at Sikhote Alin near Vladivostok in 1947. None of these were as devastating as the K-T event that doomed the dinosaurs, but many were big enough to wipe out cities or whole nations if there had been any in the vicinity at the time. And the 2807 BC event, to judge from the myths, made the December 2004 Indian Ocean tsunami look like a ripple on the beach.
The Past as Prologue
Would confirmation of a civilization-killing impact 5,000 years ago mean that another one is likely tomorrow or the next day? No, but the more large impacts there have been in the recent past, the more troubling become our prospects for the future. In fact, in the November 2007 issue of the Proceedings of the National Academy of Sciences, physicist Richard Firestone and colleagues suggest that the major climatic perturbations and extinctions at the beginning of the Younger Dryas event some 12,900 years ago were caused by an comet impact even more catastrophic than that of the 2807 BC event.
Masse's research highlights the importance not only of studying Earth's past for evidence of impacts, but of searching space for the NEOs that may be incoming. It also shows that when it comes to identifying impacts that have occurred over the last few thousand years, geophysical research isn't the only game in town. Archaeology and the study of humankind's oral traditions have unique contributions to make as well.
Rex Dalton
Nature
Thu, 13 Dec 2007 12:22 EST
Bullet-like pieces of what is thought to be an ancient meteorite shower have been found embedded in mammoth tusks and bison bone.
The discovery of the 2 - 5 millimetre holes left by meteorites opens a window into a impact event thought to have happened over Alaska and Russia tens of thousands of years ago. And it could provide a whole new way to chart impacts from space.
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| ©Firestone et al. |
| The 'bullet holes' in this tusk are found only on the skyward side. |
The fragments, found in seven mammoth tusks and the skull and horns of a Siberian bison, match the geochemical composition of iron meteorites. "We think that the micrometeorites came from an air-burst of a meteor 30,000 to 34,000 years ago," says Richard Firestone, co-author of the study and a chemist at the Lawrence Berkeley National Laboratory in California. "We think a wave of meteoric material sprayed the region."
Some of the tusks are peppered with hundreds of the fragments, which had burnt grooves into the bone. All the pieces entered the bones on the skyward surfaces of the tusks and skull.
The researchers presented their findings on 11 December at the American Geophysical Union meeting in San Francisco.
Motel dream
Strangely, the trail to finding the tusks began at a fossil sale in a motel in Arizona.
Allen West, a self-taught geophysicist based in Arizona, was looking for evidence of a meteorite that he and his colleagues think caused the wipe-out of large mammals and the Clovis people in North America some 13,000 years ago. Recalling previous visits to the annual Tucson Gem and Mineral Show, West says, "A bulb went on in my head; I remembered seeing a room full of mammoth tusks there." He reasoned that tusks or antlers of deer or elk might have inadvertently captured exploding meteoritic material. So he went to a motel that shows the fossils, and sifted through the tusks.
"I spent two or three hours looking at dirty old tusks, when suddenly there was a burnt hole," he says. He tested it with a small magnet, as he knew many meteorites were mostly iron. "Bang; it stuck right to the hole," he says.
West bought the 60-centimetre tusk for about US$200, and later headed to the warehouse of the company that he bought it from: Canada Fossils.
After three days of searching through the company's collection of some 15,000 tusks, West started to find more evidence of micrometeorites in a batch from the Yukutia Peninsula in eastern Siberia. His magnet again repeatedly hit the mark on tell-tale burn holes.
West bought these tusks too and took them to Firestone and his colleagues for geochemical analysis and radiocarbon dating.
Past blast
The geochemical analysis confirmed that the pieces had a high iron and nickel content, and were low in titanium, making them more likely to be from meteorites than from Earth-bound rocks.
The dating showed that most of the tusks were 30,000 to 34,000 years old, and so not relevant to their theory about the end of the Clovis people (for more on that theory, see Blast in the past?). One tusk dated to 21,000 years ago, and the bison skull to 26,000 years old, but Firestone thinks that the dating of these specimens might have been affected by contamination of the samples. Future work, he thinks, will probably show them to be from the same meteorite shower as the other samples. They plan to refine the dates on all specimens as they move towards publication.
Firestone and his colleagues note that other scientists have found evidence that the populations of some large mammals - such as bison, horses and mammoths - declined about 34,000 years ago. That could go well with a theory of a meteor impact at that time.
Comment: Note that 30,000 to 34,000 years is almost precisely seven to eight 4,200 year periods, coinciding with the Cycle of Cosmic Catastrophes.
The researchers hope that their find will spur others to look through fossils for signs of meteor impacts. "We're hoping that museums and universities will start examining their collections for similar specimens," says West.
NASA
Mon, 03 Dec 2007 19:50 EST
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| ©Christopher Colley |
Mark your calendar: The best meteor shower of 2007 peaks on Friday, December 14th.
"It's the Geminid meteor shower," says NASA astronomer Bill Cooke of the Marshall Space Flight Center. "Start watching on Thursday evening, Dec. 13th, around 10 pm local time," he advises. "At first you might not see very many meteors - but be patient. The show really heats up after midnight and by dawn on Friday, Dec. 14th, there could be dozens of bright meteors per hour streaking across the sky."
The Geminids are not ordinary meteors. While most meteor showers come from comets, Geminids come from an asteroid - a near-Earth object named 3200 Phaethon.
"It's very strange," says Cooke. How does an asteroid make a meteor shower?
Comets do it by evaporating. When a comet flies close to the sun, intense heat vaporizes the comet's "dirty ice" resulting in high-speed jets of comet dust that spew into interplanetary space. When a speck of this comet dust hits Earth's atmosphere traveling ~100,000 mph, it disintegrates in a bright flash of light - a meteor!
Asteroids, on the other hand, don't normally spew dust into space - and therein lies the mystery. Where did Phaethon's meteoroids come from?
One possibility is a collision. Maybe it bumped against another asteroid. A collision could have created a cloud of dust and rock that follows Phaethon around in its orbit. Such collisions, however, are not very likely.
Cooke favors another possibility: "I think 3200 Phaethon used to be a comet."
Exhibit #1 in favor of this idea is Phaethon's orbit: it is highly elliptical, like the orbit of a typical comet, and brings Phaethon extremely close to the sun, twice as close as Mercury itself. Every 1.4 years, Phaethon swoops through the inner solar system where repeated blasts of solar heat could easily reduce a flamboyant comet to the rocky skeleton we see today.
If this scenario is correct, Phaethon-the-comet may have produced many rich streams of dust that spent hundreds or thousands of years drifting toward Earth until the first Geminid meteors appeared during the US Civil War. Since then, Geminids have been a regular shower peaking every year in mid-December.
3200 Phaethon is now catalogued as a "PHA" - a potentially hazardous asteroid whose path misses Earth's orbit by only 2 million miles. It measures 5 km wide, about half the size of the asteroid or comet that wiped out the dinosaurs 65 million years ago, and can be seen through backyard telescopes - in fact, now is a good time to look:
"3200 Phaethon is flying past Earth just a few days before this year's Geminid meteor shower," notes Cooke. On Dec. 10th, Phaethon will be about 11 million miles away shining like a 14th magnitude star in the constellation Virgo: ephemeris. That's too dim for the naked eye, he says, but a good target for amateur telescopes equipped with CCD cameras.
Cooke doesn't expect the flyby to boost the Geminids - "11 million miles is too distant to affect meteor rates" - but the Geminids don't really need boosting. "It's always a great shower," he says. "Don't miss it."
Paul Icamina
All Headline News
Wed, 12 Dec 2007 11:06 EST
Bangor, Maine - Frantic calls from New Hampshire to Canada about strange lights in the sky had police scrambling to look for unidentified flying objects only to find out the fireballs coincided with Monday evening's launch from Kennedy Space Center in Florida.
A defense agency spokesman described the launch was for a "national security satellite."
Sgt. Derek Strong of the Royal Canadian Mounted Police told the Bangor Daily News that the orange lights were caused by debris re-entering the earth's atmosphere and crashing into the ocean off Point Lepreau, New Brunswick.
Ken Stewart of the U.S. Coast Guard said calls were fielded from Portsmouth, N.H., "all the way to Nova Scotia," The Associated Press reported.
The satellite launch that brought the fireballs that prompted many calls to local police.
Translated from Hebrew
Ynet
Sun, 09 Dec 2007 14:11 EST
Concerned citizens reported to Ynet about loud sounds of explosions in the area of the Central District. Some feared it was an earthquake, although the Geophysical Institute refuted this possibility. Later today the IDF responded that it is probably a sonic boom.
Several loud explosions were heard this afternoon in the Central District area. The IDF responded that apparently those were sonic booms, and the matter is under investigation. They added that during their activity, IAF makes all the possible effort to avoid interfering with the citizens' quality of life.
Not long after 16:00, Ynet was flooded with "red email" reports from concerned readers. Many readers from the Central District reported extremely loud noises and strong tremors.
According to the readers' reports, there were three sounds of explosions, with small intervals between them. Some of the readers reported that they felt the earth trembling, although Geophysical Institute refuted any possibility of an earthquake.
Jonathan, resident of Ashkelon, said that two explosion sounds were clearly heard above his house in the north part of the city. "It was a very strong boom, and the house was trembling. At first I thought that it was a bomb and immediately went outside to see what's happening, but couldn't see a thing."
Other reader reported about "two explosions at 16:05, with a two minutes interval, that shook the street. They sounded from the distance and caused car alarms to go off."
Or-Yehuda resident reported that three loud booms were heard and caused light tremor. In Kiriat Ono people reported that booms shook the houses.
During the last years there were several cases of sonic booms caused by IAF flights above the Israeli sky.
IAF used to cause sonic booms above Gaza. In 2005, the organization "Doctors for Human Rights" submitted a petition to the high court against this practice, claiming that those booms cause significant damage to the civilian population and children in Gaza. The court claimed in return that this practice has an operational importance and can't be renounced.
Comment: According to one of our Israeli readers, those booms were heard and felt along the coastline (from Ashkelon - South of the country, to Hedera - North of the country) and not only in the Central District. And although several reported the sighting of two jet fighters above the sea, it still doesn't explain the intensity and the distance those booms could be heard from.
By CHRIS LAMBIE and BRIAN MEDEL Staff Reporters
Halifax Chronicle-Herald
Fri, 14 Dec 2007 18:16 EST
The bright ball of flame that streaked across the winter sky Monday night wasn't a shooting star - it was a booster rocket that had carried a U.S. military satellite into orbit.
The fireball was visible along the South Shore as the booster plummeted into the ocean off Nova Scotia.
"We just happened to be looking in a southerly direction and (saw) a bright ball of yellow-orange flame," Yarmouth firefighter Peter Poirier said Tuesday.
He was with a crew fighting a house fire in the south end of town when firefighters spotted the ball of fire in the clear sky. They were able to track the booster's descent for about 10 seconds before it vanished.
The light definitely wasn't close, Mr. Poirier said.
"It had that orange glow that would resemble what you'd see from a flare," he said.
"But it was too big, physically, for it to be a flare."
At first, some people thought it was a small plane in trouble.
"All kinds of calls came in," Yarmouth Fire Chief Ken Kelly said Tuesday.
"A few people reported an airplane down."
The spectacular light show came courtesy of the U.S. air force, which launched the first of a new generation of military communication satellites Monday from Cape Canaveral, Fla.
The booster stage of the rocket burned up on re-entry far off the coast, said 2nd Lt. Noel Paine, a spokesman for the rescue co-ordination centre in Halifax.
"There was a fair amount of debris," Lt. Paine said. "The reason there were a lot of calls and interest was the debris burning up was quite visible, possibly from both the Nova Scotia and New Brunswick coasts."
The navy doesn't know exactly where the booster landed, said Lt.-Cmdr. Mary-Claude Gagne of Joint Task Force Atlantic.
"If we did, we probably would have recovered it, or somebody would have," she said, noting the projected drop zone for the booster ranged from 185 to 460 kilometres off Nova Scotia.
The booster was visible because it was burning as it re-entered the atmosphere, Lt.-Cmdr. Gagne said.
"It's no different than a shooting star," she said.
Most satellites are launched near the equator because it saves on fuel, said Richard Wassersug, an anatomy and neurobiology professor at Dalhousie University who has worked with NASA to conduct projects in space.
That makes seeing the rocket booster falling here an extraordinary occurrence.
"It's going to be very rare at this latitude," Mr. Wassersug said.
"It's uncommon to put something into a strongly polar orbit. So it's going to be rare to have seen boosters off of our coast coming down."
The satellite it was carrying was likely destined for a polar orbit, he said.
It will probably be used to conduct surveillance on the Russians and monitor communications in the Arctic, Mr. Wassersug said.
The booster would have been "pretty huge," he said, noting it was probably heavily damaged by heat while re-entering Earth's atmosphere.
But the odds of it falling on someone, or a ship, were astronomical.
"There's always the slim possibility of space junk coming down and hitting someone," Mr. Wassersug said. "Not all this stuff burns up completely."
Monday marked the 11th flight of an Atlas V rocket from Cape Canaveral.
The Atlas V booster carried a Wideband Global SATCOM satellite into space. The American satellite system is expected to provide better communications for marines, soldiers, sailors and airmen.
"Once the satellite we launched (Monday) becomes operational, it will become the Department of Defence's highest-capacity communications satellite and provide critical effects for our war fighters," Brig.-Gen. Susan Helms, commander of 45th Space Wing in Florida, said in a news release.
"This mission proves that control of the battlefield really does begin here."
Irene Klotz
Reuters
Fri, 14 Dec 2007 05:53 EST
CAPE CANAVERAL, Florida - Two astronauts on the International Space Station will make a spacewalk next week to find out if a micrometeoroid strike damaged a critical part of the outpost's power system, officials said on Thursday.
The station is not in any danger and is still producing enough power to support the arrival of a Russian cargo ship this month, said station deputy program manager Kirk Shireman.
Analysis is under way to determine if changes need to be made to NASA's plan to launch the space shuttle Atlantis in January with Europe's Columbus science module on board.
That flight, originally planned for last week, was postponed when sensors in the shuttle's fuel tank failed during two launch attempts.
NASA had said it would try again no earlier than January 2. But on it said it had reset the target date to January 10 to give workers more time with their families during the holidays.
Shireman said the power problem would probably not affect plans to attach Columbus to the station next month. But flights of Japanese modules in February and April could be affected.
Without repairs, "we know we can't go too much farther," he said.
Station commander Peggy Whitson and flight engineer Dan Tani are scheduled for a 6.5-hour spacewalk on Tuesday to inspect two joints needed to position the station's right-side solar panels toward the sun.
The primary joint, which rotates the panels 360 degrees, was locked in place by spacewalking astronauts in October.
A problem with a second joint, which lets the panels pivot while the primary joint is locked, surfaced on December 8. "It makes power generation much more difficult," Shireman said.
Because several independent pieces of equipment were
simultaneously affected, engineers suspect a micrometeoroid strike may
be to blame.
They also theorized a piece of debris may have worked itself free
and floated into an area that shorted out electrical components.
Spare parts to fix the second joint are on board the station, though if the problem is with the device's cables a repair would have to wait until supplies arrive on the next cargo ship or aboard the shuttle, Shireman said.
"This (spacewalk) is a fact-finding mission," he said. "It is hoped that something the crew sees can help us narrow down the problem."
(Editing by Jane Sutton)
Eric Russell
Bangor Daily News
Sat, 15 Dec 2007 07:59 EST
More strange lights were seen in the skies over Maine late Thursday night, but it's unlikely they were related to an incident earlier this week.
An Air Force spokeswoman said Friday that the sighting of "fireballs in the sky" off Maine's coast Monday evening was almost definitely part of a U.S. Air Force booster rocket.
Between 10 and 11 p.m. Thursday, Bangor police and Penobscot County sheriff dispatchers received several calls describing shafts of yellow and white light that extended from the ground to the sky. Additional sightings of an orange glow over northern Penobscot County also were reported.
A meteorologist with the National Weather Service in Caribou said there was no meteorological explanation for the lights. Rebecca Hupp, director at Bangor International Airport, said the airport did not field any calls overnight Thursday.
On Monday evening, reports flooded dispatch centers in Washington County and New Brunswick describing strange orange lights in the sky. At first there was concern that a plane had crashed in the Bay of Fundy, but a quick search by the U.S. Coast Guard revealed that was not the case.
Air Force Lt. Col. Maria Carl confirmed Friday that the Air Force launched an Atlas V booster shortly after 5 p.m. Monday from Cape Canaveral Air Force Station in Florida. It was carrying what she called National Reconnaissance Office payload, but she didn't elaborate because it was a classified mission.
Ten minutes after the booster was launched north, an expendable fuel tank separated and dropped into the Atlantic Ocean about 100 miles off Nova Scotia, she said.
"Obviously, I don't know for sure what people saw, but based on the trajectory and the timing, it seems accurate that it would have been the booster," Carl said Friday.
While her explanation might close the door on Monday's sightings, it doesn't explain the reports of orange and yellow light shafts seen Thursday.
"I can't speak to that," the Air Force spokeswoman said, "but we didn't have any additional launches, so that wasn't us."
Comment: That's an odd lack of concern over strange lights in North American air space coming from the air force.
Neil Comins, an astronomy professor at the University of Maine, said Thursday's light show could have been several things. For example, a variety of gases glow in the atmosphere.
"It's entirely plausible that what people saw last night was frozen residue [from the gases] that re-entered the atmosphere," he said.
Comins did not rule out the possibility that Thursday's sighting was related to the incident from Monday.
"There is a slim but not negligible possibility that something in orbit could have decayed at a slower rate," he said, referring to the Air Force launch.
While strange reports of lights in the sky occur several times a year, Comins said, it's uncommon to see two reports in the same week.
"So, in that sense, I can't say, 'No, they are definitely not connected,'" he said.
The lack of a conclusive explanation for either incident this week has conjured up memories of an incident that was reported 40 years ago in waters off Nova Scotia.
The "Shag Harbor Incident," which occurred Oct. 4, 1967, is one of the most-documented potential UFO sightings in history.
Similar to Monday's incident, residents of the small Nova Scotia fishing village of Shag Harbor saw unusual orange lights in the sky. After that, others saw an object descend toward the water, but instead of crashing into the ocean, it hovered on the surface, according to reports by MUFON, a large organization that investigates reports of unidentified flying objects.
The Bangor Daily News reported that residents of Washington County and elsewhere in Maine reported strange lights in the sky the same night.
The Shag Harbor Incident was investigated by the U.S. Coast Guard, and some reports indicate that an unsuccessful search was conducted.
Because the sightings could not be attributed to any military or civilian launch, the incident quickly gained infamy.
Carl didn't comment on the Shag Harbor Incident but she said that anytime the Air Force launches a booster, her office gets numerous calls, so she wasn't surprised this week.
Anne Minard
National Geographic News
Sat, 15 Dec 2007 09:09 EST
An ancient meteor impact in North America sent up waves of rock fragments that peppered prehistoric mammals with "space shrapnel" about 34,000 years ago, scientists say.
Many of the animals, particularly in the region near present-day Alaska, didn't survive.
That's the story being pieced together by a research team led by Richard Firestone of the Lawrence Berkeley National Laboratory in Berkeley, California.
The team had done previous work on a suspected impact that occurred 13,000 years ago. But while looking for evidence of that more recent blast in mammoth tusks, the scientists found traces of the much older event.
"The surprise was the tusks were dating back to 30,000 to 34,000 years ago," Firestone said.
"Nobody had thought of it before. It was serendipitous."
The work was presented this week at the fall meeting of the American Geophysical Union in San Francisco, California.
Tiny "Bullet Holes," Micrometeorites Found
While searching for evidence of the more recent cosmic impact, team member Allen West, an Arizona geophysicist, noticed an odd pattern as he was combing through thousands of ancient tusks.
He found that the top-facing sides of a few tusks were pockmarked by holes 0.08 to 0.11 inch (2 to 3 millimeters) across.
The pockmarks were found on seven mammoth tusks - most likely from near Alaska's Yukon River - and the skull and horns of a Siberian bison (see a map of Alaska).
That the holes were found on only one side of the bones indicated that the impacts came from a single direction, Firestone said.
The researchers believe the damage was caused by micrometeorites, each less than a millimeter in size, thrown off by an object that collided with Earth.
The researchers found fossilized meteorites in the holes and determined that they were rich in iron and nickel but poor in titanium - chemical traits that suggest celestial and not earthly origins, they say.
West also discovered that the tiny rocks were highly magnetic. When he suspended a magnet on a string over the holes, the magnet held fast.
The team additionally found that the bison skull showed bone growth around the holes, suggesting that the animal had survived the blast.
Catastrophic Event
Firestone said the evidence corroborates previous work done by Ian Barnes, a paleobiologist at Royal Holloway University of London.
In a paper published in the journal Current Biology in June of this year, Barnes reported molecular evidence for a die-off of mammoths around the time of the newly suspected impact.
"We are pretty certain there was one event that occurred in that region," Firestone said.
Barnes agreed the data so far could suggest a connection, but he said it's tenuous at best and more information is needed.
"Brown bears underwent a local extinction in Alaska 35,000 years ago, and there may be some turnover or reduction of the Alaskan mammoth population around 35,000 [years ago], but that data hasn't been published yet," he said.
"Whether it only happened in North America or farther afield, I don't have the data for that yet."
More Tusks Ahead
Firestone and his colleagues expect to submit their work for publication in a scientific journal in the coming year.
Meanwhile, the early evidence has already raised some perplexing questions.
"The big mystery is the nature of the impact," Firestone said.
"We don't know whether a meteor exploded or what happened. It's confounding the impact [experts]."
Barnes pointed out there have been plenty of hazards for Earth's creatures aside from meteor blasts, including volcanic eruptions and rapid climate change.
(Read related story: "Volcano Theory of Dino Die-Off Gets New Support" [November 5, 2007].)
Celestial pockmarks notwithstanding, Firestone hesitated to pin mass extinction on any one event.
"There are all sorts of events that might cause a reduction in population size, so I'm cautious about ... actually ascribing causation," he said.
Nevertheless, Barnes called the findings "pretty extraordinary," particularly because they were uncovered so unexpectedly.
"You got to give it to them - it's pretty exciting stuff," he said. "Pretty amazing."
Dave Mosher
livescience.com
Mon, 17 Dec 2007 21:28 EST
Space rocks are blamed for a lot of rough times on Earth, from the die-off of most marine animals some 250 million years ago to the disappearance of the dinosaurs 65 million years in the past.
A new theory, however, suggests that catastrophic meteorite impacts are linked to an explosion in biodiversity about 470 million years ago, during the Ordovician Period. Within a few million years, the number of trilobite species and scores of other creatures on Earth jumped at least three to four times.
Birger Schmitz, a geologist at the University of Lund in Sweden who worked for more than 10 years to help gather evidence backing up the claim, is the first to admit that his group's findings are hard to swallow.
"It seems completely at odds with anyone's expectations," Schmitz said, "but you have to remember, for example, that it was at first difficult for many scientists to accept asteroid explanations for the disappearance of the dinosaurs."
Schmitz and his colleagues detail their findings in the Dec. 16 advance issue of the journal Nature Geoscience.
Smackdown
Just before the jolt to Ordovician life, Schmitz said two massive bodies in the Asteroid Belt slammed into one another, littering the solar system with rocks the size of Manhattan island and ranging down to microscopic bits of dust.
"Even today, more than 20 percent of the meteorites we see came from this breakup event," Schmitz said. That makes the L-chondrite meteorites, as they're known, the most common kind to rain down on Earth.
Such extraterrestrial rocks contain a unique form of radioactive chromium, so Schmitz and his team were able to figure out precisely when, how much and how often the cosmic debris slammed into Earth.
"We saw a sudden jump in meteorite material around the time of increased biodiversity," Schmitz said - greater than 100 times more material, in fact. "That's a major event, and an incredible coincidence that I don't think we should ignore," he told LiveScience.com.
Schmitz cautioned that while the two events line up in an uncanny way, there is still a lot of work left to do to connect the increased meteorite impacts to inflating biodiversity.
"It took us about 15 years to accumulate data for this finding, and it's something that isn't just a computer model or simulation. It's real, tactile evidence," he said of the work, which included slowly acid-dissolving almost a ton of rock collected from around the world to sift out bits of chromium.
The scientists compared their meteorite record to layers of fossilized plants and animals, determining that the cosmic smashup happened shortly before the biodiversity boost.
"I expect that it will take us another 15 years of playing in the dirt to get there, to find Ordovician impact craters and beds associated with this breakup," he said.
Pushing their luck
Schmitz isn't certain exactly how pummeling the planet with rocks could cause life to thrive, but he thinks it has something to do with creating new nooks and crannies for life to adapt to in its new environment.
"Before the breakup you had primitive animals adapted to rough conditions, so you could say they were prepared for the storm," Schmitz said.
Schmitz also explained that evolution is very much "give-and-take," as radiating into new species requires a figurative kick in the shins.
"If you push an ecosystem too hard, you'll destroy it," he said. "But for the organisms living on Earth at the time, [the environment] pushed them to adapt and fill new niches. It's like at the university: I tell my students all the time that if we don't push you, you don't evolve."
Whether or not the cosmic smashup ultimately caused life on Earth to thrive 470 million years ago, the connection between events in space and life on Earth is intriguing, Schmitz said.
"There's much more to be learned how the history of Earth and its life is related to the universe," he said. "We're only in the beginning of exploring that connection."
David Shiga
New Scientist
Mon, 17 Dec 2007 03:35 EST
A comet targeted for a flyby with NASA's Deep Impact spacecraft cannot be found, forcing mission planners to send the probe to a different comet. The comet may have evaded telescopes simply because its predicted orbit was incorrect, or, more intriguingly, it might have disintegrated completely.
 |
| ©Illustration: JPL/NASA |
| The Epoxi mission was diverted to comet Hartley 2, after its original target comet, 85P/Boethin, could not be found |
The Deep Impact spacecraft completed its main mission in 2005, when it slammed a metal impactor into comet Tempel 1 and watched the debris fly. After the successful encounter with Tempel 1, the mission team had hoped to carry out a second rendezvous, this time with a comet called 85P/Boethin, in late 2008.
But the team now says comet Boethin is nowhere to be found, forcing them to target a different comet called Hartley 2 instead.
Comet Boethin has been spotted only twice, first when it was discovered during a close approach to the Sun in 1975, and again during a second close passage in 1986.
The comet was not seen when it was expected to approach the Sun most recently in 1997. But that is not surprising since it was behind the glare of the Sun as seen from Earth that time, says Michael A'Hearn of the University of Maryland in Baltimore, US, chief scientist for the extended mission.
In October, some of the world's most powerful telescopes, including
the Very Large Telescope (VLT) array in Paranal, Chile, and the Subaru
observatory in Hawaii combed the skies for the comet, but failed to see
it.
Crumble away
It is possible that the comet was destroyed during the 1997 Sun encounter, disintegrating from the Sun's heat, A'Hearn says. But comet Boethin never comes closer to the Sun than just beyond Earth's orbit, making it unlikely to have disintegrated, he says.
"Disappearing in the sense of breaking up and dissipating is actually very rare" for such a comet, he told New Scientist. "If it disappeared, then that is fascinating in itself - only one other comet has done that in recent memory." Comet Linear-S4 disintegrated and disappeared in 2000. A comet called 73P/Schwassmann-Wachmann 3 was seen fragmenting in 2006, but it did not crumble away to invisibility.
A somewhat more likely possibility is that the comet broke into a
few large chunks that are still intact but have drifted too far from
the original comet's orbit to have been spotted in searches to date,
A'Hearn says.
Uncertain orbit
However, the most likely explanation of all is that telescopes have simply been searching in the wrong place, he says. Because the comet has been briefly spotted only twice, scientists have not been able to compute its path around the Sun very precisely.
Despite the uncertainty in comet Boethin's orbit, the Deep Impact team had selected it as a target because it would have been relatively quick and easy to get to, reducing the cost of the extended mission.
Now, NASA has decided to divert the spacecraft to Hartley 2 instead. Hartley 2 is about 1.6 kilometres across, about the same size as comet Boethin. Although it will take longer to get there - the encounter will not occur until 2010 - Hartley 2 is more active than Boethin was, which will give the spacecraft more to look at.
The spacecraft turned on its rocket engine for three minutes on 1 November, setting up for a flyby of Earth on 31 December, the first of three Earth encounters that will use our planet's gravity to adjust the spacecraft's trajectory for its new mission.
Pummelled by dust
The spacecraft will pass within about 1000 kilometres of the comet. Trying to get much closer than that would risk the spacecraft getting pummelled by dust particles, which can do a lot of damage due to their high speeds, A'Hearn says.
Only a small number of comets have been seen up close. Adding another to the mix will help scientists understand better which features tend to be the same and which vary from comet to comet, he adds.
The Deep Impact spacecraft's extended mission has been named EPOXI. The spacecraft will also use its camera to watch stars with so-called transiting planets - planets known to pass in front of their parent star as seen from Earth, periodically blocking some of the starlight.
The way the starlight varies as the planet moves in front of the star could lead to the discovery of rings or moons around the known planets, and possibly result in the discovery of additional planets with masses as small as three times that of Earth.
Sandia National Laboratories
Tue, 18 Dec 2007 15:02 EST
The stunning amount of forest devastation at Tunguska a century ago in Siberia may have been caused by an asteroid only a fraction as large as previously published estimates, Sandia National Laboratories supercomputer simulations suggest.
"The asteroid that caused the extensive damage was much smaller than we had thought," says Sandia principal investigator Mark Boslough of the impact that occurred June 30, 1908. "That such a small object can do this kind of destruction suggests that smaller asteroids are something to consider. Their smaller size indicates such collisions are not as improbable as we had believed."
 |
| ©Randy Montoya |
| INCINERATION POSSIBLE - Fine points of the "fireball" that might be expected from an asteroid exploding in Earth's atmosphere are indicated in a supercomputer simulation devised by a team led by Sandia researcher Mark Boslough. |
Because smaller asteroids approach Earth statistically more frequently than larger ones, he says, "We should be making more efforts at detecting the smaller ones than we have till now."
The new simulation - which more closely matches the widely known facts of destruction than earlier models - shows that the center of mass of an asteroid exploding above the ground is transported downward at speeds faster than sound. It takes the form of a high-temperature jet of expanding gas called a fireball.
This causes stronger blast waves and thermal radiation pulses at the surface than would be predicted by an explosion limited to the height at which the blast was initiated.
"Our understanding was oversimplified," says Boslough, "We no longer have to make the same simplifying assumptions, because present-day supercomputers allow us to do things with high resolution in 3-D. Everything gets clearer as you look at things with more refined tools."
Sandia is a National Nuclear Security Administration laboratory.
The new interpretation also accounts for the fact that winds were amplified above ridgelines where trees tended to be blown down, and that the forest at the time of the explosion, according to foresters, was not healthy. Thus previous scientific estimates had overstated the devastation caused by the asteroid, since topographic and ecologic factors contributing to the result had not been taken into account.
"There's actually less devastation than previously thought," says Boslough, "but it was caused by a far smaller asteroid. Unfortunately, it's not a complete wash in terms of the potential hazard, because there are more smaller asteroids than larger ones."
Boslough and colleagues achieved fame more than a decade ago by accurately predicting that that the fireball caused by the intersection of the comet Shoemaker-Levy 9 with Jupiter would be observable from Earth.
Simulations show that the material of an incoming asteroid is compressed by the increasing resistance of Earth's atmosphere. As it penetrates deeper, the more and more resistant atmospheric wall causes it to explode as an airburst that precipitates the downward flow of heated gas.
Because of the additional energy transported toward the surface by the fireball, what scientists had thought to be an explosion between 10 and 20 megatons was more likely only three to five megatons. The physical size of the asteroid, says Boslough, depends upon its speed and whether it is porous or nonporous, icy or waterless, and other material characteristics.
"Any strategy for defense or deflection should take into consideration this revised understanding of the mechanism of explosion," says Boslough.
One of most prominent papers in estimating frequency of impact was published five years ago in Nature by Sandia researcher Dick Spalding and his colleagues, from satellite data on explosions in atmosphere. "They can count those events and estimate frequencies of arrival through probabilistic arguments," says Boslough.
The work was presented at the American Geophysical Union meeting in San Francisco on Dec. 11. A paper on the phenomenon, co-authored by Sandia researcher Dave Crawford and entitled "Low - altitude airbursts and the impact threat" has been accepted for publication in the International Journal of Impact Engineering.
The research was paid for by Sandia's Laboratory-Directed Research and Development office.
Laura Knight-Jadczyk
SOTT.NET Book Review
Wed, 19 Dec 2007 08:08 EST
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| ©n/a |
| Medieval depiction of the Black Death |
New Light on the Black Death: The Cosmic Connection by dendrochronologist Mike Baillie of Queen's University, Belfast, Ireland.
I just finished reading this one and all I can say is: Wow! This was an intense book! Not a long one, either - just 208 pages including appendices. It's tight and economical with no wasted words or idle rambling around. Every example and temporary diversion is crucial to the central argument which is - brace yourself for this one - Mike Baillie (yeah, a real scientist and not a crackpot), is saying that the Black Death, one of the most deadly pandemics in human history, said to have killed possibly two thirds of the entire population of Europe, not to mention millions all over the planet, probably wasn't Bubonic Plague but was rather Death By Comet(s)!
Oh yeah! That's far out, isn't it?
Maybe not. Baillie has the scientific evidence to support his theory and his evidence actually supports - and is supported by - what the people of the time were saying: earthquakes, comets, rains of death and fire, corrupted atmosphere, and death on a scale that is almost unimaginable. Most people nowadays are not really aware of what happened just 660 years ago. (Hmmm... the inquiring mind immediately wonders what might happen when we hit 666 years after?! That would be 2012...)
Anyway, China, where the Black Death is said to have originated, lost around half of its entire population (going from around 123 million to around 65 million).
Recent research into European death tolls also suggest a figure of 45% to 50% of the total European population dying during a four-year period though the figure fluctuated from place to place (which is a problem as we will see).
In Mediterranean Europe and Italy, the South of France and Spain, where the plague ran for about four years consecutively, it was probably closer to 70% to 75% of the total population. (In the USA today, that would be equivalent to reducing the population from its current 300 million total to 75 million in less than four years. That would also amount to having to bury or dispose of around 225 million corpses!)
In Germany and England it was probably closer to 20%. Northeastern Germany, Bohemia, Poland and Hungary are believed to have suffered less for some reason (and there are a few theories which are not entirely satisfactory).
There are no estimates available for Russia or the Balkans so it seems that they may have suffered little, if at all. Africa lost approximately 1/8th of its population (from around 80 million to 70 million). (These figures actually highlight one of the problems that Baillie brings up: the variability of death rates according to location.)
Whatever the death rate in any given location, the bottom line is that the Black Death produced the largest death toll from any known pandemic in recorded history and, as Baillie points out, nobody really knows what it was! Oh, of course, for a very long time everybody just "knew" it was Bubonic plague, so how is it that Baillie questions this well-established fact? He's not the only one.
In 1984, Graham Twigg published The Black Death: A Biological Reappraisal, where he argued that the climate and ecology of Europe and particularly England made it nearly impossible for rats and fleas to have transmitted bubonic plague and that it would have been nearly impossible for Yersinia pestis to have been the causative agent of the plague, let alone its explosive spread across Europe during the 14th century. Twigg also demolishes the common theory of entirely pneumonic spread. He proposes, based on his examination of the evidence and symptoms, that the Black Death may actually have been an epidemic of pulmonary anthrax caused by Bacillus anthracis.
Another unhappy camper in the standard model is Gunnar Karlsson who, in 2000, pointed out that the Black Death killed between half and two-thirds of the population of Iceland, although there were no rats in Iceland at this time. (The History of Iceland by Gunnar Karlsson)
Baillie sums up the problem as follows:
The Black Death of 1347 was believed to be the third great outbreak of bubonic plague; a plague that is traditionally spread by rats and fleas. The previous instances were the Plague of Athens in 430 BC and the plague at the time of Justinian which arrived into Constantinople in AD 542. The Plague of Athens was described by Thucydides, while the Justinian plague was described by Procopius, among others. [...]
The plague is supposed to have originated in Central Asia, or somewhere in Africa, where plague is endemic in some rodent populations. It is assumed that some environmental stimulus caused infected rodents to leave their normal habitats and infect rat populations, and ultimately human populations, in areas where there was no natural immunity. The mechanism of transfer is believed to have been infected fleas leaving the bodies of dead rats and moving to human hosts who were in turn infected by the feeding fleas. It is believed that trade routes brought the disease to the Black Sea region and from there to the central Mediterranean by late 1347. It was then introduced into Europe through northern Italy and southern France. It immediately started killing people in large numbers spreading overland at about 1.5 km per day. Between January and the summer to autumn of 1348 it had spread as far as the British Isles, and by 1350 to Scandinavia and eventually even Iceland. The spread seems to have curled up through France, across Belgium into Germany and on into central southern Europe. This first wave burned itself out by 1351, though there was a second wave in 1361.
It is generally believed that the plague hit an already weakened population in Europe. [...]
At its most basic, the problem is with those rats and fleas. For the conventional wisdom to work there have to be hosts of infected rats and they have to be moving at alarming speed - you would almost have to imagine infected rats scuttling every onward (mostly northward) delivering, as they died, loads of infected fleas. The snags with this scenario are legion. For example, there are no descriptions of dead rats lying everywhere (this is explained by suggesting that either the rats were indoors, or people were so used to dead rats that they were not worth mentioning; though if they were indoors how did they travel so fast?) It did not seem to matter whether you were a rural shepherd or cleric or a town dweller, both were infected. Yet strangely with this very infectious disease some cities across Europe were spared. Moreover, these rats must have been happy to move to cool northern areas even though bubonic plague is a disease that requires relatively warm temperatures. Then, when there are water barriers, these rats board ships to keep the momentum going. (Baillie)
Benedictow, an advocate of the rats and fleas scenarios quoted by Baillie, tells us about these amazing critters:
The Black Death's strategic genius made also another masterstroke that greatly increased the pace of its conquest of the Iberian peninsula. Shortly after its multiple invasions of important urban centres along the coast of the Kingdom of Aragon, it performed a remarkable metastatic leap and arrived triumphantly in the town of Santiago de Compostela in the very opposite, north-westernmost corner of the Iberian Peninsula. (Benedictow, O. J. 2004 The Black Death 1346-1353: The Complete History. The Boydell press, Woodbridge.)
In 2001, epidemiologists Susan Scott and Christopher Duncan from Liverpool University proposed the theory that the Black Death might have been caused by an Ebola-like virus, not a bacterium. Their research and findings are thoroughly documented in Biology of Plagues. More recently the researchers have published computer modeling demonstrating how the Black Death has made around 10% of Europeans resistant to HIV. (Return of the Black Death: The World's Greatest Serial Killer by Susan Scott, Christopher Duncan and Biology of Plagues: Evidence from Historical Populations by Susan Scott, Christopher J. Duncan)
In a similar vein, historian Norman F. Cantor, in his 2001 book In the Wake of the Plague, suggests the Black Death might have been a combination of pandemics including a form of anthrax and a cattle murrain. He cites many forms of evidence including: reported disease symptoms not in keeping with the known effects of either bubonic or pneumonic plague, the discovery of anthrax spores in a plague pit in Scotland, and the fact that meat from infected cattle was known to have been sold in many rural English areas prior to the onset of the plague.
Samuel K. Cohn, quoted extensively by Baillie also rebutted the theory (and that's really all it is, and a weak theory at that!) that the Black Death was bubonic plague. In the Encyclopedia of Population, he points to five major weaknesses in this theory:
- very different transmission speeds - the Black Death was reported to have spread 385 km in 91 days in 664, compared to 12-15 km a year for the modern Bubonic Plague, which has the assistance of trains and cars
- difficulties with the attempt to explain the rapid spread of the Black Death by arguing that it was spread by the rare pneumonic form of the disease - in fact this form killed less than 0.3% of the infected population in its worst outbreak in Manchuria in 1911
- different seasonality - the modern plague can only be sustained at temperatures between 50 and 78 °F (10 and 26 °C) and requires high humidity, while the Black Death occurred even in Norway in the middle of the winter and in the Mediterranean in the middle of hot dry summers
- very different death rates - in several places (including Florence in 1348) over 75% of the population appears to have died; in contrast the highest mortality for the modern Bubonic Plague was 3% in Mumbai in 1903
- the cycles and trends of infection were very different between the diseases - humans did not develop resistance to the modern disease, but resistance to the Black Death rose sharply, so that eventually it became mainly a childhood disease
Cohn also points out that while the identification of the disease as having buboes relies on the account of Boccaccio and others, they described buboes, abscesses, rashes and carbuncles occurring all over the body, while the modern disease rarely has more than one bubo, most commonly in the groin, and is not characterized by abscesses, rashes and carbuncles which is what Boccaccio described!
The gist of Cohn's argument is that whatever caused the Black Death, it was not bubonic plague. (See also: Samuel K. Cohn 2002, "The Black Death: End of the Paradigm." and The Black Death and the Transformation of the West (European History Series) by David Herlihy and Samuel K., Jr. Cohn)
When one begins to dig into the subject, we find that there was one study that claimed that tooth pulp tissue from a fourteenth-century plague cemetery in Montpellier tested positive for molecules associated with Y. pestis (bubonic plague). Similar findings were reported in a 2007 study, but other studies have not supported these results. In fact, in September of 2003, a team of researchers from Oxford University tested 121 teeth from sixty-six skeletons found in fourteenth-century mass graves. The remains showed no genetic trace of Y. pestis, and the researchers suspect that the Montpellier study was flawed[
What these studies do not address is the problem that the apparent means of infection or transmission varied widely, from human-to-human contact as in Iceland (rare for plague and cutaneous Bacillus anthracis) to infection in the absence of living or recently-dead humans, as in Sicily (which speaks against most viruses).
To all the problems with the Bubonic Plague theory cited above, we have to add what the contemporary writers recorded. Philip Ziegler collected many of these items in his book The Black Death, though he dismisses them as "metaphor". We'll be looking at some of them in just a moment.
Mike Baillie didn't start out to write a book about cometary impacts being implicated in the great Pandemics of the past; he had just noticed some strange tree ring patterns that happened to coincide with this historical catastrophe and thought that, perhaps, there was some sort of environmental downturn that weakened the human population, making humanity susceptible to bacterial or viral death on a large scale. But, what he found was a dangling thread that, once he began to pull on it, unraveled the "accepted wisdom" about the Black Death and sent him off on a search that led to completely astonishing conclusions.
As mentioned, the first clue was tree rings - that's natural since Baillie is a dendrochronologist. He compared these tree rings to dated ice-core samples that had been analyzed and discovered a very strange thing: ammonium. There are, as it happens, four occasions in the last 1500 years where scientists can confidently link dated layers of ammonium in Greenland ice to high-energy atmospheric interactions with objects coming from space: 539, 626, 1014, and 1908 - the Tunguska event. In short, there is a connection between ammonium in the ice cores and extra-terrestrial bombardment of the surface of the earth.
Now notice that the above statement is that there are four events that can be definitively linked with high-energy interactions; Baillie presents the research in this book showing that the exact same signature is present at the time of the Black Death in both the tree rings and in the ice cores, AND at other times of so-called "plague and pandemic".
As it happens, the ammonium signal in the ice-cores is directly connected to an earthquake that occurred on January 25th, 1348 - and Baillie discovers that there was a 14th century writer who wrote that the plague was a "corruption of the atmosphere" that came from this earthquake!
How could a plague come from an earthquake, you ask?
Baillie points out that we don't always know if earthquakes are caused by tectonic movements; they could be cause by cometary explosions in the atmosphere or even impacts on the surface of the earth.
In Rain of Iron and Ice by John Lewis, Professor of Planetary Sciences at the Lunar and Planetary Laboratory, Co-director of the NASA/University of Arizona Space Engineering Research Center, and Commissioner of the Arizona State Space Commission, tells us that the earth is regularly hit by extraterrestrial objects and many of the impacting bodies explode in the atmosphere as happened in Tunguska, leaving no craters or long-lasting visible evidence of a body from space.
But just because there is no long-lasting evidence doesn't mean there is no significant effect on the planet and/or its inhabitants! These impacts or atmospheric explosions may produce earthquakes or tsunamis without any witnesses being aware of the cause. After all, the earth is 75% water and any eye-witness to such an event would very likely be fried and never tell about it, so we really have no way of knowing if all the earthquakes on our planet are tectonic in nature or not.
Lewis points out:
In an average year there is one atmospheric explosion with a yield of 100 kilotons or more. The large majority occur in such remote areas, or so high in the atmosphere, that they are not observed. Even if observed, the witnesses may see only a flash of light in the distance, or hear the 'rumble of distant thunder' coming from the open oceans. Thus even those that are observed are often not recognized. (Lewis, Rain of Iron and Ice)
As Baillie points out, Lewis is talking about a "typical" year and it is obvious, from other studies, that not all years are equal - some are less typical than others! Baillie writes:
As Lewis pointed out, we know from many strands of evidence broadly what the impact rate should be over time. The fact that impacts are not in the historical record [or not admitted or discussed by historians or archaeologists] is not because none happened. After all, there are those well-attested crater fields that were formed in the last few millennia in Estonia, Poland, Germany and Italy - which were not recorded historically; their existence was deduced from holes in the ground. So we know the recording mechanism is flawed! What needs to be added ... is one key piece of intuitive thinking. Here is a quote from Lewis' Scenario D:
(In this scenario) In 1946 a 25,000-metric-ton achondritic fireball explodes at 4:00 AM local time at a height of 11km above Fergana, Uzbekistan. The 1-megaton blast damages buildings over an area several kilometers in diameter, searing the area with intense heat and setting thousands of fires. The fires burn out of control, killing 4,146. Over 20,000 residents are awakened by the brilliant flash of light and heat to find their city in flames. An 'earthquake' is reported by the survivors. Several metric tons of meteorite fragments are mixed in with the debris of 2000 burned-out and collapsed buildings, where they are indistinguishable from scorched and blackened fragments of structural brick and rock. (Lewis quoted by Baillie)
The point of this is that there is almost no way to monitor whether or not any given disaster/catastrophe is definitively an impact as opposed to a violent earthquake. The result is that centuries could be passing, with numerous cometary impacts happening all the time, and no one suspecting the true hazards from space! As Baillie points out: there are many earthquakes recorded in history, but NO impacts! And yet, there is the evidence that the impacts HAVE happened - on the ground, and in the ice cores. And there is Tunguska.
Reports of the Tunguska event tell us that the ground shook around the impact/explosion zone for a radius of about 900km. At the time of any larger impact event, the earthquake would be proportionally more severe. Any survivors of such an event who are far enough away to survive, would only have seen a flash, felt a tremor, and heard a loud rumbling noise. If they were too far away to see the flash, or were indoors, they would only report an earthquake.
In short, what the work of Lewis brings to the table is the idea that some well-known historical earthquakes could very well have been impact events. Baillie mentions that one obvious prospect is the great Antioch earthquake of AD 526 which was described by John Malalas:
...those caught in the earth beneath the buildings were incinerated and sparks of fire appeared out of the air and burned everyone they struck like lightning. The surface of the earth boiled and foundations of buildings were struck by thunderbolts thrown up by the earthquakes and were burned to ashes by fire... it was a tremendous and incredible marvel with fire belching out rain, rain falling from tremendous furnaces, flames dissolving into showers ... as a result Antioch became desolate ... in this terror up to 250,000 people perished. (Jeffreys, E., Jeffreys, M. and Scott, R. 1986, The Chronicle of John Malalas, Byzantina Australiensia, Australian Assoc. Byzantine Studies 4, Melbourne.)
Baillie also points out that a series of such impacts/overhead explosions, would more adequately explain the longstanding problem of the end of the Bronze Age in the Eastern Mediterranean in the 12th century BC. At that time, many - uncountable - major sites were destroyed and totally burned and it has all been blamed on those supernatural "Sea Peoples." If that was the case, if it was invasion and conquest, there ought to at least be some evidence for that, like dead warriors or signs of warfare... but for the most part, that is not the case. There were almost no bodies found, and no precious objects except those that were hidden away as though someone expected to return for them, or didn't have time to retrieve them. The people who fled (extra-terrestrial events often have precursor activities and warnings because a comet can be observed approaching for some time) were probably also killed in the act of fleeing and the result was total abandonment and total destruction of the cities in question.
And the onset of Dark Ages.
So, the possibility that many destructions of the past could have been related to impact events has never been taken seriously or tested and this could be a perilous error.
The question that Baillie asks, but never really answers is: What was it that so successfully stopped people asking why there is a traditional and deeply ingrained fear of comets in the psyche of humanity? He points out that, yes, there are people outside of mainstream academia who ask these questions. But why, against all good common sense is this subject so widely and systematically ignored, marginalized and ridiculed?
The odd thing is that, even though Baillie points out that many high-level scientists and government agencies are taking these things seriously (Lewis, for example), it is still ignored, marginalized and ridiculed to the general public via the mainstream media! Baillie writes:
In case readers think this is simply rhetoric, this is as good a place as any to mention a forthcoming event. On 13 April 2029 an asteroid named Apophis will pass by the earth at a distance of less than 50,000km. If you're alive at the time, and it is not cloudy, you'll be able to see it pass with the naked eye. Apophis is more than 300m in diameter. If, as it passed the earth, it just happens to pass through a certain narrow window in space, then, in 2036 it will return and hit the earth (this narrow window is a point where the earth's gravity would deflect the orbit of Apophis just enough to ensure an impact in 2036). If Apophis hits the earth the impact will be in the 3000-megaton class. It is entirely reasonable to state that such an impact, taking place anywhere on the planet, would collapse our current civilization and return the survivors, metaphorically speaking, to the Dark Ages (it is believed that in such an event globalised institutions, such as the financial and insurance markets would collapse, bringing down the entire interconnected monetary, trade and transport systems). Impacts from space are not fiction, and it seems highly likely that quite a number have taken place in the last few millennia (over and above the small crater-forming examples already mentioned). It is just that, for some reason, most people who study the past have chosen to avoid, or ignore, the issue. (Baillie)
Along with the science, Baillie cites contemporary evidence - some of this evidence has been relegated to "myth" - from around the globe that indicate that the earth was, indeed, subjected to bombardment from space during the 14th century and that this may very well have been not only the cause of the 25 January 1348 earthquake, but also the cause of the Black Death. Baillie quotes a great selection of material from contemporary accounts including the work of Ziegler cited above:
Droughts, floods, earthquakes, locusts, subterranean thunder, unheard of tempests, lightning, sheets of fire, hail stones of marvelous size, fire from heaven, stinking smoke, corrupted atmosphere, a vast rain of fire, masses of smoke. (Ziegler)
Ziegler discounts entirely reports of a black comet seen before the arrival of the epidemic but records: heavy mists and clouds, falling stars, blasts of hot wind, a column of fire, a ball of fire, a violent earth tremor, in Italy a crescendo of calamity involving earthquakes, following which, the plague arrived. (Baillie)
As it happens, in the 1340s there was a veritable rash of earthquakes. In Rosemary Horrox's book, The Black Death, quoted by Baillie, we find that a contemporary writer in Padua reported that not only was there a great earthquake on 25 January 1348, but it was at the twenty-third hour.
In the thirty-first year of Emperoro Lewis, around the feast of the Conversion of St. Paul (25 January) there was an earthquake throughout Carinthia and Carniola which was so severe that everyone feared for their lives. There were repeated shocks, and on one night the earth shook 20 times. Sixteen cities were destroyed and their inhabitants killed.... Thirty-six mountain fortresses and their in habitants were destroyed and it was calculated that more than 40,000 men were swallowed up or overwhelmed.
(The author goes on to say that he received information from "a letter of the house of Friesach to the provincial prior of Germany):
It says in the same letter that in this year [1348] fire falling from heaven consumed the land of the Turks for 16 days; that for a few days it rained toads and snakes, by which many men were killed: that a pestilence has gathered strength in many parts of the world. (Horrox)
From Samuel Cohn's book:
... a dragon at Jerusalem like that of Saint George that devoured all that crossed its path .... A city of 40,000 ... totally demolished by the fall from heaven of a great quantity of worms, big as a fist with eight legs, which killed all by their stench and poisonous vapours. (Cohn)
A story by the Dominican friar Bartolomeo:
... massive rains of worms and serpents in parts of China, which devoured large numbers of people. Also in those parts fire rained from Heaven in the form of snow (ash), which burnt mountains, the land, and men. And from this fire arose a pestilential smoke that killed all who smelt it within twelve hours, as well as those who only saw the poison of that pestilential smoke. (Cohn)
Cohn writes:
Nor were such stories merely the introductory grist of naïve merchants and possibly crazed friars ... [even] ... Petrarch's closes friend, Louis Sanctus, before embarking on his careful reporting of the plague... claimed that in September floods of frogs and serpents throughout India had presaged the coming to Europe in January of the three pestilential Genoese galleys... [even] ... the English chronicler Henry Knighton ... [reported how] ... at Naples the whole city was destroyed by earthquake and tempest. Numerous chroniclers reported earthquakes around the world, which prefigured the unprecedented plague. Most narrowed the event to Vespers, 25 January 1348. [...]
Of these earthquakes that "destroyed many cities, towns, churches, monasteries, towers, along with their people and beasts of burden, the worst hit was Villach in southern Austria. Chroniclers in Italy, Germany, Austria, Slavonia, and Poland said it was totally submerged by the quake with one in 10 surviving. (Cohn)
A continental text dated Sunday 27 April 1348 states:
They say that in the three months from 25 January [1348] to the present day, a total of 62,000 bodies were buried in Avignon. (Horrox)
A German treatise unearthed by Horrox says:
Insofar as the mortality arose from natural causes its immediate cause was a corrupt and poisonous earthy exhalation, which infected the air in various parts of the world... I say it was the vapour and corrupted air which has been vented - or so to speak purged - in the earthquake that occurred on St. Paul's day [1348], along with the corrupted air vented in other earthquakes and eruptions, which has infected the air above the earth and killed people in various parts of the world. (Horrox)
As Baillie notes, if this oft-cited earthquake was, in reality, the result of cometary impacts then the corrupted air could be from one or two causes: high-energy chemical transformations in the atmosphere or outgassings from the earth itself.
The German Historian, Hecker, informs us:
On the island of Cyprus, the plague from the East had already broken out; when an earthquake shook the foundations of the island, and was accompanied by so frightful a hurricane, that the inhabitants... fled in dismay... The sea overflowed... Before the earthquake, a pestiferous wind spread so poisonous an odour that many, being overpowered by it, fell down suddenly and expired in dreadful agonies. ... and as at that time natural occurrences were transformed into miracles, it was reported that a fiery meteor, which descended on the earth far in the East, had destroyed everything within a circumference of more than a hundred leagues, infecting the air far and wide. (Cohn)
Jon Arrizabalaga compiled a selection of writings in an attempt to understand what educated people were saying about the Black Death while it was happening. Regarding the terms used by doctors and other medical people in 1348 to describe the plague, he writes:
One... Jacme d'Agramaont, discussed it in terms of an "epidemic or pestilence and mortalities of people" which threatened Lerida from "some parts and regions neighbouring to us" ... Agramont said nothing concerning the term epidemia, but he extensively developed what he meant by pestilencia. He gave this latter term a very peculiar etymology, in accordance with a from of knowledge established by Isidore of Seville (570=636) in his Etymologiae, which came to be widely accepted throughout Europe during the Middle Ages. He split the term pestilencia up into three syllables, each having a particular meaning: pes = tempesta: 'storm, tempest'; te = 'temps, time', lencia = clardat: 'brightness, light'; hence, he concluded, the pestilencia was 'the time of tempest caused by light from the stars.'
As it happens, Isidore of Seville lived not long after another period of cometary bombardment over Europe which is also evident in the tree ring and ice core studies. On August 17, 1999, the Knight Ridder Washington Bureau published an article by Robert S. Boyd entitled: Comets may have caused Earth's great empires to fall which included the following:
Analysis of tree rings shows that at in 540 AD in different parts of the world the climate changed. Temperatures dropped enough to hinder the growth of trees as widely dispersed as northern Europe, Siberia, western North America, and southern South America.
A search of historical records and mythical stories pointed to a disastrous visitation from the sky during the same period, it is claimed. There was one reference to a "comet in Gaul so vast that the whole sky seemed on fire" in 540-41.
According to legend, King Arthur died around this time, and Celtic myths associated with Arthur hinted at bright sky Gods and bolts of fire.
In the 530s, an unusual meteor shower was recorded by both Mediterranean and Chinese observers. Meteors are caused by the fine dust from comets burning up in the atmosphere. Furthermore, a team of astronomers from Armagh Observatory in Northern Ireland published research in 1990 which said the Earth would have been at risk from cometary bombardment between the years 400 and 600 AD. [...]
Famine followed the crop failures, and hard on its heels bubonic plague that swept across Europe in the mid-6th century. [...]
At this time, the Roman emperor Justinian was attempting to regenerate the decaying Roman empire. But the plan failed in 540 and was followed by the Dark Ages and the rise of Islam.
There is a large body of material from that period which consistently points to a "corrupted atmosphere," breathe the air and you die", and somehow, the ocean was involved as well as earthquakes and comets and fireballs in the sky. A report of the Medical Faculty of Paris prepared in October 1348 says:
Another possible cause of corruption, which needs to be borne in mind, is the escape of the rottenness trapped in the center of the earth as a result of earthquakes - something that has indeed recently occurred. (quoted by Baillie)
In short, the French were aware of a series of earthquakes at the time that may have been caused by cometary impacts. One report of that period says that an earthquake lasted for six days and another claimed the period was ten days. Such events could also produce outgassing of all sorts of unpleasant chemicals which could kill. Consider the following:
The Lake NYOS Gas Explosion, Cameroon 1986
[...]
Although a sudden outgassing of CO2 had occurred at Lake Monoun in 1984, killing 37 local residents, a similar threat from Lake Nyos was not anticipated. However, on August 21, 1986, a limnic eruption occurred at Lake Nyos which triggered the sudden release of about 1.6 million tonnes of CO2. The gas rushed down two nearby valleys, displacing all the air and suffocating up to 1,800 people within 20 km of the lake, mostly rural villagers, as well as 3,500 livestock. About 4,000 inhabitants fled the area, and many of these developed respiratory problems, burns, and paralysis as a result of the gases.It is not known what triggered the catastrophic outgassing. Most geologists suspect a landslide, but some believe that a small volcanic eruption may have occurred on the bed of the lake. [...]
It is believed that up to a cubic kilometre of gas was released. Because CO2 is denser than air, the gas flowed off the mountainous flank in which Lake Nyos rests and down two adjoining valleys in a layer tens of metres deep, displacing the air and suffocating all the people and animals before it could dissipate. The normally blue waters of the lake turned a deep red after the outgassing, due to iron-rich water from the deep rising to the surface and being oxidised by the air. The level of the lake dropped by about a metre, representing the volume of gas released. The outgassing probably also caused an overflow of the waters of the lake. Trees near the lake were knocked down.
Hmmm... one wonders if similar events could be triggered by cometary impacts and if outgassing from oceans could be as dangerous and deadly? One also wonders, considering the fact that trees were "knocked down," if this outgassing might not have been an impact event?
Baillie takes us through the science with hard numbers and graphs and shows us how these things were spoken about plainly by those who experienced the Black Death but, for some reason, modern historians all think these remarks about rains of fire and death and air that could kill were all just metaphors for a horrible disease. In the end, it is the science that must win on this one because totally independent workers studying comets, tsunami, carbon dioxide, ice cores and tree rings all observe in their data something very strange happening globally around the time that the Black Death decimated the human population of the Earth.
Baillie notes in his closing remarks, worth repeating here:
It is increasingly evident that intellectually the world is divided into two. There are those who study the past, in the fields of history and archaeology, and see no evidence for any human populations ever having been affected by impacts from space. In diametric opposition to this stance there are those who study the objects that come close to, and sometimes collide with, this planet. Some serious members of this latter group have no doubt whatsoever that there must have been numerous devastating impacts in the last five millennia; the period of human civilization.
And yet, nobody talks about it.
There really is quite sufficient data presented in Baillie's book to support the theory that the Black Death was due to an impact by Comet Debris - similar to the impacts on Jupiter by the fragments of Comet Shoemaker-Levy back in 1994. As to exactly how these deaths occurred, there are a number of possibilities: earthquakes, floods (tsunami), rains of fire, chemicals released by the high-energy explosions in the atmosphere, including ammonium and hydrogen cyanide, and possibly even comet born disease pathogens.
If it has happened as often as Baillie suggests, it can happen again. And if, as we suspect, the Earth is slated for a bombardment in the not too distant future, it seems that there are more ways to die in such an event than just getting hit by a comet fragment.
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| ©Jason Engle |
| The Black Death: The Legends of Fire Breathing Dragons may have originated from Cometary disasters |
New Light on the Black Death: The Cosmic Connection by dendrochronologist Mike Baillie of Queen's University, Belfast, Ireland, published by Tempus, 2006.
Dr Mike Baillie is a Professor Emiritus of Palaeoecology in the School of Archaeology and Palaeoecology at Queen's University of Belfast in Northern Ireland.
Baillie is a leading expert in dendrochronology, or dating by
means of tree-rings. In the 1980s, he was instrumental in building a
year-by-year chronology of tree-ring growth reaching 7,400 years into
the past.
Sandia National Laboratories
Mon, 17 Dec 2007 22:04 EST
 |
| INCINERATION POSSIBLE - Fine points of the "fireball" that might be expected from an asteroid exploding in Earth's atmosphere are indicated in a supercomputer simulation devised by a team led by Sandia researcher Mark Boslough. (Photo by Randy Montoya) |
The stunning amount of forest devastation at Tunguska a century ago in Siberia may have been caused by an asteroid only a fraction as large as previously published estimates, Sandia National Laboratories supercomputer simulations suggest.
"The asteroid that caused the extensive damage was much smaller than we had thought," says Sandia principal investigator Mark Boslough of the impact that occurred June 30, 1908. "That such a small object can do this kind of destruction suggests that smaller asteroids are something to consider. Their smaller size indicates such collisions are not as improbable as we had believed."
Because smaller asteroids approach Earth statistically more frequently than larger ones, he says, "We should be making more efforts at detecting the smaller ones than we have till now."
The new simulation - which more closely matches the widely known facts of destruction than earlier models - shows that the center of mass of an asteroid exploding above the ground is transported downward at speeds faster than sound. It takes the form of a high-temperature jet of expanding gas called a fireball.
This causes stronger blast waves and thermal radiation pulses at the surface than would be predicted by an explosion limited to the height at which the blast was initiated.
"Our understanding was oversimplified," says Boslough, "We no longer have to make the same simplifying assumptions, because present-day supercomputers allow us to do things with high resolution in 3-D. Everything gets clearer as you look at things with more refined tools."
Sandia is a National Nuclear Security Administration laboratory.
The new interpretation also accounts for the fact that winds were amplified above ridgelines where trees tended to be blown down, and that the forest at the time of the explosion, according to foresters, was not healthy. Thus previous scientific estimates had overstated the devastation caused by the asteroid, since topographic and ecologic factors contributing to the result had not been taken into account.
"There's actually less devastation than previously thought," says Boslough, "but it was caused by a far smaller asteroid. Unfortunately, it's not a complete wash in terms of the potential hazard, because there are more smaller asteroids than larger ones."
Boslough and colleagues achieved fame more than a decade ago by accurately predicting that that the fireball caused by the intersection of the comet Shoemaker-Levy 9 with Jupiter would be observable from Earth.
Simulations show that the material of an incoming asteroid is compressed by the increasing resistance of Earth's atmosphere. As it penetrates deeper, the more and more resistant atmospheric wall causes it to explode as an airburst that precipitates the downward flow of heated gas.
Because of the additional energy transported toward the surface by the fireball, what scientists had thought to be an explosion between 10 and 20 megatons was more likely only three to five megatons. The physical size of the asteroid, says Boslough, depends upon its speed and whether it is porous or nonporous, icy or waterless, and other material characteristics.
"Any strategy for defense or deflection should take into consideration this revised understanding of the mechanism of explosion," says Boslough.
One of most prominent papers in estimating frequency of impact was published five years ago in Nature by Sandia researcher Dick Spalding and his colleagues, from satellite data on explosions in atmosphere. "They can count those events and estimate frequencies of arrival through probabilistic arguments," says Boslough.
The work was presented at the American Geophysical Union meeting in San Francisco on Dec. 11. A paper on the phenomenon, co-authored by Sandia researcher Dave Crawford and entitled "Low - altitude airbursts and the impact threat" has been accepted for publication in the International Journal of Impact Engineering.
The research was paid for by Sandia's Laboratory-Directed Research and Development office.
Movie Clips of the fireball simulations are available:
Movie 1
Movie 2
Movie 3
Movie 4
Movie 5
Movie 6
Movie 7
Movie 8
Charles Q. Choi
Space.com/Yahoo!News
Wed, 19 Dec 2007 07:39 EST
The infamous Tunguska explosion, which mysteriously leveled an area of Siberian forest nearly the size of Tokyo a century ago, might have been caused by an impacting asteroid far smaller than previously thought.
The fact that a relatively small asteroid could still cause such a massive explosion suggests "we should be making more efforts at detecting the smaller ones than we have till now," said researcher Mark Boslough, a physicist at Sandia National Laboratory in Albuquerque, N.M.
The explosion near the Podkamennaya Tunguska River on June 30, 1908, flattened some 500,000 acres (2,000 square kilometers) of Siberian forest. Scientists calculated the Tunguska explosion could have been roughly as strong as 10 to 20 megatons of TNT - 1,000 times more powerful than the atom bomb dropped on Hiroshima.
Wild theories have been bandied about for a century regarding what caused the Tunguska explosion, including a UFO crash, antimatter, a black hole and famed inventor Nikola Tesla's "death ray." In the last decade, researchers have conjectured the event was triggered by an asteroid exploding in Earth's atmosphere that was roughly 100 feet wide (30 meters) and 560,000 metric tons in mass - more than 10 times that of the Titanic.
The space rock is thought to have blown up above the surface, only fragments possibly striking the ground.
Now new supercomputer simulations suggest "the asteroid that caused the extensive damage was much smaller than we had thought," Boslough said. Specifically, he and his colleagues say it would have been a factor of three or four smaller in mass and perhaps 65 feet (20 meters) in diameter.
The simulations run on Sandia's Red Storm supercomputer - the third fastest in the world - detail how an asteroid that explodes as it runs into Earth's atmosphere will generate a supersonic jet of expanding superheated gas. This fireball would have caused blast waves that were stronger at the surface than previously thought.
At the same time, previous estimates seem to have overstated the devastation the event caused. The forest back then was not healthy, according to foresters, "and it doesn't take as much energy to blow down a diseased tree than a healthy tree," Boslough said. In addition, the winds from the explosion would naturally get amplified above ridgelines, making the explosion seem more powerful than it actually was. What scientists had thought to be an explosion between 10 and 20 megatons was more likely only three to five megatons, he explained.
All in all, the researchers suggest that smaller asteroids may pose a greater danger than previously believed. Moreover, "there are a lot more objects that size," Boslough told SPACE.com.
NASA Ames Research Center planetary scientist and astrobiologist David Morrison, who did not participate in this study, said, "If he's right, we can expect more Tunguska-sized explosions - perhaps every couple of centuries instead of every millennia or two." He added, "It raises the bar in the long term - ultimately, we'd like to have a survey system that can detect things this small."
Boslough and his colleagues detailed their findings at the American Geophysical Union meeting in San Francisco on Dec. 11. A paper on the phenomenon has been accepted for publication in the International Journal of Impact Engineering.
Comment: Actually it appears that small asteroids or comets hit the earth far more often than thought or reported. Read the latest SOTT focus: New Light on the Black Death: The Cosmic Connection to get the idea...
Karen Hopkin
Scientific American
Thu, 20 Dec 2007 15:33 EST
If you woke up this morning and the newspaper headline screamed Meteor Headed for Earth, you'd think: That's not good. And you'd probably be right. But sometimes a little cosmic bombardment can be just what the doctor ordered. In a study published online in the journal Nature Geoscience, researchers in Sweden say that 470 million years ago, meteor showers might have boosted our biodiversity.
The scientists were studying rocks from China and Scandinavia. And they were looking for two things. First, they were counting the number of different clam-like species they could find. Second, they were searching for chemicals that were carried here by meteorites - extraterrestrial chromite, stuff like that.
They found that a huge burst of diversification coincides exactly with a time when meteors a mile wide were raining down on the planet. But wait. Didn't an asteroid wipe out the dinosaurs? Well, yes, but without all those earlier impacts promoting diversity, maybe there wouldn't have been any dinosaurs in the first place. And if a meteor hadn't then slammed the dinos, mammals like us might never have made the scene. So when it comes to space rocks, one man's ceiling is another man's flora...and fauna.
John Johnson Jr.
Los Angeles Times
Thu, 20 Dec 2007 12:20 EST
Talk about your cosmic pileups.
An asteroid similar to the one that flattened forests in Siberia in 1908 could plow into Mars sometime in the next few weeks, scientists said.
Researchers attached to NASA's Near-Earth Objects Program, who like to call themselves the Solar System Defense Team, have been tracking the asteroid for days.
The scientists, based at the Jet Propulsion Laboratory in La Cañada Flintridge, put the chances that it will hit the Red Planet at about 1 in 300. That's better odds than any known asteroid has ever had of hitting Earth, except for the Siberian strike, the scientists said.
The unnamed asteroid is about 160 feet across, which puts it in the range of the famous Siberian rock. The largest impact event in recent history, that explosion felled 80 million trees over an area of 830 square miles.
Concerns about another strike on Earth led to the creation of the Near-Earth Objects Program and the pursuit of research into possible ways of deflecting a killer asteroid.
Scientists say it's unclear what the effects of such an impact on Mars would be. The Martian atmosphere is so thin that an asteroid would likely plummet all the way to the surface instead of breaking up above ground, as happened in the Siberian event.
Once it hit, it would probably create a large crater and send plumes of dust high into the atmosphere, scientists said. Depending on where it hit, the plume could be visible through telescopes on Earth.
The Mars Reconnaissance Orbiter, which is currently mapping the planet, would have a front-row seat. NASA's two JPL-built rovers, Opportunity and Spirit, might also be able to take pictures from the ground of the impact's effects.
spaceweather.com
Fri, 21 Dec 2007 00:28 EST
Comet 8P/Tuttle is coming and it is bringing a meteor shower with it. "We could be in for a Merry surprise on Dec. 22nd when Earth passes through a trail of comet dust," says astronomer Peter Jenniskens of the SETI Institute.
Previous returns of Comet Tuttle to the inner solar system have been attended by outbursts of meteors, most recently in 1980 and 1994. During those flurries, dozens of meteors per hour streamed from the constellation Ursa Minor--hence the name of the shower, "the Ursids."
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| ©Chris Schur |
| Comet 8P/Tuttle photographed Dec. 2nd by Chris Schur of Payson, AZ. The 7th magnitude comet is visible through binoculars in the constellation Cassiopeia. |
Although Ursids have a reputation for being faint, "we are not certain about this," says Jenniskens. "Because winter weather keeps many observers indoors, Ursid outbursts have never been widely observed and they may contain a fair number of bright meteors. We have a lot to learn." That's why he hopes sky watchers will keep an eye on the northern sky this weekend; Ursid meteors emerge not far from the north star, Polaris.
According to models by Jenniskens and colleagues, the peak will occur between 2100 and 2200 UT (4-5 pm EST) on Dec. 22nd with meteors visible as much as four hours before and after that time. Anything could happen, from a dud to a blast. Bundle up and look!
RIA Novosti
Fri, 21 Dec 2007 12:48 EST
An asteroid, which is believed to be on a collision course with Mars, will not affect the Earth if it hits the 'Red' planet in January 2008, a Russian Academy of Science spokesman said on Friday.
Sergei Smirnov said the asteroid, which is traveling at 8 miles per second, was discovered in November by American scientists.
He said the explosion could be on a scale equal to the Tunguska event, when a meteorite, which crashed into central Siberia in 1908 caused destruction on a nuclear scale. The enigma still thrills scientists all over the world.
"It will not influence the Earth in any way," Smirnov said.
The scientist said that if the collision takes place, it will not be visible without high-definition telescopes, but would still provide valuable scientific data: "The object is sure to change its flight path, and this will considerably enrich our knowledge of the mass and density of asteroids."
He also said a large asteroid was expected to pass near Earth in 2028 which could cause a major disaster if it collides with the planet.
Alicia Chang
Associated Press
Sat, 22 Dec 2007 10:08 EST
LOS ANGELES - Mars could be in for an asteroid hit. A newly discovered hunk of space rock has a 1 in 75 chance of slamming into the Red Planet on Jan. 30, scientists said Thursday.
"These odds are extremely unusual. We frequently work with really long odds when we track ... threatening asteroids," said Steve Chesley, an astronomer with the Near Earth Object Program at NASA's Jet Propulsion Laboratory.
The asteroid, known as 2007 WD5, was discovered in late November and is similar in size to an object that hit remote central Siberia in 1908, unleashing energy equivalent to a 15-megaton nuclear bomb and wiping out 60 million trees.
Scientists tracking the asteroid, currently halfway between Earth and Mars, initially put the odds of impact at 1 in 350 but increased the chances this week. Scientists expect the odds to diminish again early next month after getting new observations of the asteroid's orbit, Chesley said.
"We know that it's going to fly by Mars and most likely going to miss, but there's a possibility of an impact," he said.
If the asteroid does smash into Mars, it will probably hit near the equator close to where the rover Opportunity has been exploring the Martian plains since 2004. The robot is not in danger because it lies outside the impact zone. Speeding at 8 miles a second, a collision would carve a hole the size of the famed Meteor Crater in Arizona.
In 1994, fragments of the comet Shoemaker-Levy 9 smacked into Jupiter, creating a series of overlapping fireballs in space. Astronomers have yet to witness an asteroid impact with another planet.
"Unlike an Earth impact, we're not afraid, but we're excited," Chesley said.
Comment: Not afraid but excited??? Are they nuts?
Brian Handwerk
National Geographic News
Fri, 21 Dec 2007 18:33 EST
A huge explosion that devastated a swath of Siberia a century ago was caused by an asteroid that was much smaller than had previously been believed, according to new research.
The blast produced an enormous fireball over the Tunguska region of northwestern Russia in June 1908 (see map). The so-called Tunguska event leveled trees up to 10 miles (16 kilometers) away.
New supercomputer models of the event show that the devastation may have been the result of a surprisingly small asteroid that never hit the ground.
Because smaller asteroids approach Earth's orbit more often than larger ones, the discovery could also mean that Earth is at increased risk of asteroid impacts.
"I'm not sure it puts it into a whole new class of risk," said study author Mark Boslough, a physicist at Sandia National Nuclear Security Administration laboratory in Albuquerque, New Mexico.
"But there's so much uncertainty in terms of knowing if there's one
million or ten million of these things out there of a given size in
Earth-crossing orbits."
Asteroid the Size of the White House
The Tunguska explosion had previously been estimated at 10 to 20 megatons, but Boslough suggests it was three to five megatons - still hundreds of times as powerful as the atomic bomb dropped on Hiroshima in 1945.
The incoming asteroid, moving at some 40 to 60 times the speed of sound, had roughly the same mass as a solid rock the size of the White House, the new study found.
This mass is what helped produce such widespread destruction from a relatively small package, Boslough explained.
As the asteroid streaked toward Earth's surface, growing resistance from the atmosphere compressed the rocky object until its kinetic energy was converted to heat, causing it to explode into vapor with tremendous violence.
"Unlike a nuclear bomb, which doesn't have a lot of mass, this has a lot of mass which carries all that explosive energy downward toward the surface," Boslough said.
spaceweather.com
Mon, 24 Dec 2007 19:00 EST
Mark your calendar: On Jan. 29, 2008, one night before a Tunguska-class (50m-wide) asteroid threatens to strike Mars, an even larger asteroid will fly past our own planet.
At closest approach, 2007 TU24 will be 1.4 lunar distances from Earth. There's no danger of a collision, but the 400m-wide space rock will be close enough to photograph through backyard telescopes as it speeds through the constellation Cassiopeia glowing like a 10th magnitude star.
Michael Goodspeed
thunderbolts.info
Fri, 21 Dec 2007 08:13 EST
For several weeks in the fall of 2007, amateur astronomers and sky watchers around the world were entranced by the mysterious, energetic display of Comet Holmes 17P. The Internet still abounds with exotic theories about the comet's nature -- some have claimed it is the "Blue Kachina" foretold in Hopi Prophecy, others assert that the secret government shot it with a nuclear missile, and still others say its nucleus is acquiring mass and turning into a PLANET.
Garish and unfounded speculations aside, it is interesting that Comet Holmes, while providing a remarkable cometary "light show" and inciting great interest, never appeared to the naked eye as more than a tiny, luminous "fluff ball" of light. Certainly, without the aid of telescopes and space satellites, its unremarkable glow amongst a vast network of stars and planets would not have captured the average person's attention. Nor would anyone observing it have had any reason to feel terror.
But according to the ancient record, comets have long aroused terror in human beings, and this fear has clearly persisted into modern times. Even the astronomical mainstream recognizes that comets have historically been viewed as portents of destruction. The NASA report "Comets in Ancient Cultures" observes: "Comets have inspired dread, fear, and awe in many different cultures and societies around the world and throughout time. They have been branded with such titles as 'the Harbinger of Doom' and 'the Menace of the Universe.'"
In fact, increasing numbers of scientists may be coming to see that the global theme of the Doomsday comet is not a figment of human imagination, but a universal memory yet to be deciphered. The recent Discover Magazine article "Did a Comet Cause the Great Flood?" discusses the research of Bruce Masse, an environmental archaeologist at Los Alamos National Laboratory. Masse says of ancient petroglyphs depicting coiling serpents, "You can't tell me that isn't a comet." Masse concludes that, perhaps 5,000 years ago, a body three-miles wide smashed into the ocean off the coast of Madagascar. A watery cataclysm ensued, killing roughly eighty percent of the world's population.
But of course, this is not a new idea. In the 17th century, the English theologian and mathematician William Whiston and many of his followers had already linked the Biblical deluge to the arrival of a comet. A poignant illustration of this connection is the 1840 painting by John Martin, "The Eve of the Deluge." It depicts onlookers observing the arrival of a comet, in advance of the Great Flood.
While Masse's theory is surely a step in the right direction, it must ultimately fail, because it does not confront the heart of the ancient message. This message can become comprehensible only when investigators are willing to consider the details provided by the ancient witnesses themselves -- even when these details are uncomfortable to modern science. The evidence must not be examined selectively. Myth counts as evidence when widely separated cultures say precisely the same thing. And if they say the same things on a broad range of details, it then becomes clear that the evidence could not exist without the shared experience that provoked it.
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| ©Unknown |
| The famous Chinese dragon was characterized by flaming, lightning-like emanations. |
For example, when Masse points to a serpent pictograph and insists it is a comet, that itself is not persuasive at all (and when has an observed comet in modern times ever produced a full spiral?) It is the complete story of the cosmic serpent, reconstructed from the points of agreement from far-flung cultures around the world, that definitively establishes the serpent as a comet image -- from the Egyptian Apep to the Babylonian Tiamat, from the Norse Midgard serpent to the Aztec "Fire Serpent" Xiuhcoatl. But mainstream science has not yet shown either the courage or openness of mind necessary to see this story without ideological prejudice. The truth of the matter is that the lens through which mainstream astronomers and archaeologists consider ancient testimony cannot fail to distort the message.
Astronomers and astrophysicists today still view comets as icy bodies moving through electrically neutral space. To hold to this position, they have steadfastly ignored or dismissed the overwhelming evidence for an electric comet model. And in doing so, they have failed resoundingly to anticipate the accumulating surprises, many of which were predicted by Electric Universe proponent Wallace Thornhill and his colleagues. These surprises include:
Highly energetic supersonic jets exploding from comets' nuclei; the inexplicable confinement of these jets into narrow filaments, spanning great distances, up to MILLIONS of miles, defying the behavior of neutral gases in a vacuum; jets occurring on the dark sides of comet nuclei; comet surfaces with sharply carved relief -- the exact opposite of what astronomers expected under the "dirty snowball" model; unexpectedly high temperatures and X-ray emissions from cometary comas; a short supply or complete absence of water and other volatiles on comets' nuclei; mounting evidence for the production of the radical OH in cometary comas, due to charge exchange with the Sun (the process that misled astronomers into thinking they were seeing evidence of water removed from the surface.); mineral particles that can only be formed under extremely high temperatures -- the last thing one would expect from a chunk of dirty ice arriving from the outermost reaches of the solar system; comets flaring up while in "deep freeze," beyond the orbit of Saturn; comets disintegrating many millions of miles from the Sun; comet dust particles more finely and evenly divided than is plausible for sublimating "dirty ices"; ejection of larger particles and "gravel" that was never anticipated under the idea that comets accreted from primordial clouds of ice, gas, and dust; the unexplained ability of a relatively minuscule comet nucleus to hold in place a highly spherical coma, up to millions of miles in diamater, against the force of the solar wind. (For background on the electric comet, click here)
So we must now ask if the avalanche of recent comet discoveries, ranging from "surprising" to "astonishing," can help us to understand the comet-like "dragon" of world mythology?
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| ©Unknown |
| Enhanced image of comet Hale-Bopp, 1997 |
Without question, the dragon is virtually always connected to undeniably ELECTRICAL events in the sky. In its attack, lightning and thunder shake the earth. The ancient Anzu epic from Mesopotomia, depicting the fiery battle of the dragon and the god Ninurta, states, "Clouds of death rained down, an arrow flashed lightning. 'Wizzed' the battle force roared between them." In Hesiod's well-known account of the dragon Typhon's attack, the earth "groaned" beneath the god Zeus, "and the heat and blaze from both of them were on the dark-faced sea, from the thunder and lightning of Zeus and from the flame of the monster, from his flaming bolts, and from the scorch and breath of his storm winds."
The Sumerian texts describe the goddess Inanna as a blazing, destructive celestial force: "Like a dragon you have deposited venom on the land...raining the fanned fire down upon the nation...With a roaring storm you roar...devastatrix of the lands...Mankind comes before you in fear and trembling at your tempestuous radiance.
The Babylonian texts depict the goddess Ishtar in her terrible aspect: "...shining torch of heaven and earth...furious irresistible onslaught... I rain down like flames..."
Identical imagery occurs in Egyptian texts. The goddess Sekhmet becomes the Uraeus serpent raging in the sky: "A flame of fire in her tempest...the fear of me is in their hearts...the awe of me is in their hearts...No one at all can approach her...The streams behind her are flames of fire."
These are just a few instances -- out of hundreds -- pointing to the electrical properties of the cosmic serpent or dragon. If astronomers, scientists, and archaeologists are truly interested in human memories of cometary catastrophe, it is intellectually indefensible to ignore the overwhelming consensus of the testimony. And this consensus leads inexorably to decades of evidence from plasma experiments (a field largely ignored by mainstream astronomers).
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| ©Unknown |
| Left: An electric spark in a laboratory; Right: Enigmatic petroglyph on cave wall in Chaco canyon in Mexico. |
Electrified plasma -- a medium defined by the presence of charged particles -- will naturally generate filamentary, twisted, spiraling, and life-like structure. This characteristic of electric currents is also seen in the so-called "magnetic ropes" recently observed by the THEMIS spacecraft connecting the Sun and the earth (see The Electric Sun/Earth Connection). The dragon's effusive feathers, long-flowing beard, streaming mane or hair, fiery breath and "lightning" like emanations -- all ancient hieroglyphs for the comet -- are the well-documented characteristics of plasma discharge. In its electric displays, an energetic comet gives us the perfect corollary to the cosmic dragon.
But if we are permitted to draw conclusions from the ancient testimony, the tale of the Doomsday comet surely does not end with the cosmic serpent/dragon. An abundance of testimony reveals, for example, an inseparable connection of the attacking serpent or dragon with the "terrible aspect" of the mother goddess, precisely as indicated by more than one of the quotes above. This goddess figure stands at the heart of the ancient cultures -- an object of both reverence and terror. And in fact, innumerable goddesses acquire a comet-like appearance -- wildly disheveled hair, flaming countenance, accompanied by chaotic hordes or clouds of chaos, threatening to destroy the world. The moment one accepts the compelling memories of a serpent or dragon's assault, it is no longer reasonable to exclude the equally compelling ancient profiles of the mother goddess. As we shall report in the conclusion of this piece, the ancients' story of the Doomsday comet, when fully appreciated, will change our view of human history, and alter the course of science as well.
Astrobiology Magazine
Tue, 25 Dec 2007 16:45 EST
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| ©Unknown |
Astrobiology Magazine is looking back over 2007, highlighting the Top 10 astrobiology stories of the year. At number 9 is a story about a breakup event in the main asteroid belt. This event produced the impactor that hit Earth 65 million years ago, ending the age of the dinosaurs and having a profound effect on the evolution of life as we know it. (This story was originally published on September 8, 2007.)
The impactor believed to have wiped out the dinosaurs and other life forms on Earth some 65 million years ago has been traced back to a breakup event in the main asteroid belt. The finding provides insights into one of the most important extinction events in Earth's history. Known as the Cretaceous-Tertiary (K-T) extinction, this impact event signaled a dramatic change in the evolutionary history of Earth. Understanding the origins and effects of this event can not only teach us about the past, but can also help us understand how future impacts could alter our planet's global biosphere.
A joint U.S.-Czech team from Southwest Research Institute (SwRI) and Charles University in Prague suggests that the parent object of asteroid (298) Baptistina disrupted when it was hit by another large asteroid, creating numerous large fragments that would later create the Chicxulub crater on the Yucatan Peninsula as well as the prominent Tycho crater found on the Moon. The team of researchers, including Dr. William Bottke (SwRI), Dr. David Vokrouhlicky (Charles University, Prague) and Dr. David Nesvorny (SwRI), combined observations with several different numerical simulations to investigate the Baptistina disruption event and its aftermath. A particular focus of their work was how Baptistina fragments affected the Earth and Moon.
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| ©Southwest Research Institute |
| The new study suggests that the parent object of asteroid (298) Baptistina was hit by another large asteroid, creating numerous large fragments that would later create the Chicxulub crater on the Yucatan Peninsula as well as the prominent Tycho crater found on the Moon. |
At approximately 170 kilometers in diameter and having characteristics similar to carbonaceous chondrite meteorites, the Baptistina parent body resided in the innermost region of the asteroid belt when it was hit by another asteroid estimated to be 60 kilometers in diameter. This catastrophic impact produced what is now known as the Baptistina asteroid family, a cluster of asteroid fragments with similar orbits. According to the team's modeling work, this family originally included approximately 300 bodies larger than 10 kilometers and 140,000 bodies larger than 1 kilometer.
Once created, the newly formed fragments' orbits began to slowly evolve due to thermal forces produced when they absorbed sunlight and re-radiated the energy away as heat. According to Bottke, "By carefully modeling these effects and the distance traveled by different-sized fragments from the location of the original collision, we determined that the Baptistina breakup took place 160 million years ago, give or take 20 million years."
The gradual spreading of the family caused many fragments to drift into a nearby "dynamical superhighway" where they could escape the main asteroid belt and be delivered to orbits that cross Earth's path. The team's computations suggest that about 20 percent of the surviving multi-kilometer- sized fragments in the Baptistina family were lost in this fashion, with about 2 percent of those objects going on to strike the Earth, a pronounced increase in the number of large asteroids striking Earth.
Support for these conclusions comes from the impact history of the Earth and Moon, both of which show evidence of a two-fold increase in the formation rate of large craters over the last 100 to 150 million years. As described by Nesvorny, "The Baptistina bombardment produced a prolonged surge in the impact flux that peaked roughly 100 million years ago. This matches up pretty well with what is known about the impact record."
Bottke adds, "We are in the tail end of this shower now. Our simulations suggest that about 20 percent of the present-day, near-Earth asteroid population can be traced back to the Baptistina family."
The team then investigated the origins of the 180 kilometer diameter Chicxulub crater, which has been strongly linked to the extinction of the dinosaurs 65 million years ago. Studies of sediment samples and a meteorite from this time period indicate that the Chicxulub impactor had a carbonaceous chondrite composition much like the well-known primitive meteorite Murchison. This composition is enough to rule out many potential impactors but not those from the Baptistina family. Using this information in their simulations, the team found a 90 percent probability that the object that formed the Chicxulub crater was a refugee from the Baptistina family.
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| ©NASA |
| Artist's depiction of the Chicxulub impact crater. The total number today of objects a kilometer in diameter or larger, a size that could cause a similar global catastrophe upon Earth impact, is now estimated to range between 900 and 1,230. |
These simulations also showed there was a 70 percent probability that the lunar crater Tycho, an 85 kilometer crater that formed 108 million years ago, was also produced by a large Baptistina fragment. Tycho is notable for its large size, young age and its prominent rays that extend as far as 1,500 kilometers across the Moon. Vokrouhlicky says, "The probability is smaller than in the case of the Chicxulub crater because nothing is yet known about the nature of the Tycho impactor."
This study demonstrates that the collisional and dynamical evolution the main asteroid belt may have significant implications for understanding the geological and biological history of Earth.
As Bottke says, "It is likely that more breakup events in the asteroid belt are connected in some fashion to events on the Earth, Moon and other planets. The hunt is on!"
The article, "An asteroid breakup 160 Myr ago as the probable source of the K/T impactor," was published in the Sept. 6 issue of Nature.
The NASA Origins of Solar Systems, Planetary Geology and Geophysics, and Near-Earth Objects Observations programs funded Bottke's and Nesvorny's research; Vokrouhlicky was funded by the Grant Agency of the Czech Republic.
Associated Press
Tue, 25 Dec 2007 16:25 EST
Could it have been Rudolph's nose, gleaming brightly? Or maybe just a meteorite in the making?
All across Central last night, there were reports of a fireball seen streaking to the ground.
Keith Clinton, who lives east of Bend says he saw a "large, bright green fireball descend out of the cloudless sky east of Bend."
Clinton says the fireball turned yellow and exploded about 10 degrees above the horizon, breaking into several pieces as it did.
Meanwhile, near Redmond, Spencer Krueger reported that his wife had seen a "fist-sized flaming orange ball with a tail."
And someone near Prineville called the Crook County sheriff's office to report a meteorite that had come crashing to the ground.
Authorities checked with the Redmond Airport to see if any small planes had gone off radar screens or gone missing, but nothing of the sort was reported.
KRNV
Tue, 25 Dec 2007 16:29 EST
Officials are trying to determine what people saw streaking across the sky last evening above Spanish Springs north of Reno.
Washoe County sheriff's deputies and search and rescue team members think they may be looking for a meteorite.
A caller told the sheriff's office of seeing a bright red, blue and yellow light falling from the sky north of Winnemucca Ranch Road.
Off-duty search and rescue people in the area saw the same thing and began looking for a possible meteorite.
Tammy Plotner
universetoday.com
Fri, 28 Dec 2007 21:50 EST
Beginning each New Year and lasting for nearly a week, the Quadrantid Meteor Shower sparkles across the night sky for nearly all viewers around the world.
Its radiant belongs to an extinct constellation once known as Quadran Muralis, but any meteors will seem to come from the general direction of bright Arcturus and Boötes.
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| ©Unknown |
This is a very narrow stream, which may have once belonged to a portion of the Aquarids, but recent scientific data points to a what may have been a cosmic collision.
According the most recent data, the Quandrantid meteors may have been formed about five centuries ago when a near-Earth asteroid named 2003 EH1 and a comet smashed into one another. Historic records from ancient China put comet C/1490 Y1 in the path of probability. As Jupiter's gravity continues to perturb the stream, another 400 years may mean this shower will become as extinct as the constellation for which it was once known... But NASA scientists and astronomers are taking to the skies to study the event.
A Gulfstream V aircraft will fly scientists and their instruments for 10 continuous hours over the Arctic to observe and record meteor activity. From above the Earth, the stream can be studied without light pollution and clouds to determine when the activity peaks and how the stream is dispersed. "We will fly to the North Pole and back to compensate for Earth's rotation and to keep the stream in view throughout the flight," said Peter Jenniskens, a principal investigator at NASA's Ames Research Center.
According to NASA, scientists believe this could be the most brilliant meteor shower in 2008 with over 100 visible meteors per hour at its peak. Best viewing times with the highest meteor rates are expected to be in either the late evening of Jan. 3 over Europe and western Asia or the early morning of Jan. 4 over the eastern United States. For the USA: 6pm - 2am (Pacific Time) on Jan. 3 and 4, 2008. For Northern Europe: 2am - 10am (London) on Jan. 4, 2008. For Northern Asia: 11am - 7pm (Tokyo) on Jan. 4, 2008. For almost of us, this means bundling up against the cold and battling the remnants of the waning Moon... But the sight of even one "shooting star" can make the trip worthwhile!
Will the Quadrantid Meteor Shower live up to its expectations? No one knows for sure... But we'll be watching!
Leonard David
Live Science
Sat, 29 Dec 2007 16:56 EST
The chance that a rogue mini-world - asteroid 2007 WD5 - will smack into Mars on January 30th has increased from 1.3 percent to 3.9 percent.
That's the new estimation from officials at the Near Earth Object Program at the Jet Propulsion Laboratory (JPL), stemming from several sky watching teams in Alaska, New Mexico, and in Arizona.
"The impact probability resulting from the recent orbit refinement has increased to a surprising 3.9 percent...about 1 in 25 odds," explain JPL's Near Earth Object Program website, updated today regarding the asteroid meets Mars altercation.
Still, there remains an uncertainty, although a Mars impact is still possible. However, the most likely scenario in the weeks to come is that more observations of the asteroid will allow that uncertainty to shrink - so that a Mars impact is definitely ruled out.
The JPL website notes that, in the unlikely event of an impact, the head-on collision would take place on January 30th at 2:55 a.m. Pacific Standard Time, with an uncertainty of a few minutes.
Nothing to set your watch by...but a big event in our time.
Charles Q. Choi
Space.com
Sat, 29 Dec 2007 17:04 EST
For millennia, comets were believed to be omens of doom. Instead, solving the mysteries regarding these "dirty snowballs" could help reveal the part they played in the birth of life on Earth, as well as secrets concerning the rest of the galaxy.
Did comets help create Earth's seas?
For years scientists thought comets slamming against the newborn Earth helped deliver water to a once dry planet. But roughly a decade ago this view was shaken by the discovery that the water in comets and Earth's oceans did not match up in terms of hydrogen isotopes.
Calculations then showed it was highly improbable that enough icy rocks from the suspected homes of comets - the Kuiper belt past Neptune and the Oort cloud past that - could have collided with Earth to supply its oceans.
In the last two years, however, researchers have discovered comets in the outer part of the asteroid belt. These "main-belt comets" may have the right levels of hydrogen isotopes, and are perhaps close enough to Earth to have realistically brought us the seas that life emerged from.
"No one knows for certain yet where Earth's oceans came from," said University of Hawaii astrophysicist David Jewitt. "Earth's oceans are likely a mixture of water from all sorts of places, but the main-belt comets are very likely one of them."
Where do comets come from?
The suspected homes of comets include the Oort cloud, the Kuiper belt and now the asteroid belt. But are there more reservoirs of comets yet to be found?
The Oort cloud is a theoretical cloud of icy rocks roughly 4.6 trillion miles (7.5 trillion kilometers) from the sun thought to be the source of long-period comets - that is, ones that take more than a few centuries to complete their orbits. It was once thought the original home of short-period comets as well, until calculations suggested that was impossible.
About 20 years ago, the Kuiper belt roughly 4.6 billion miles (7.5 billion kilometers) from the sun was then proposed to be the home of short-period comets. "But measurements taken in the last few years raise some doubts about that," Jewitt explained. "Maybe there are other reservoirs of comets yet to be discovered."
Secrets regarding the birth of the solar system?
Comets were long thought to be primordial relics, pristine leftovers from the protoplanetary disk that once surrounded the newborn sun. As such, it was supposed they might hold secrets untouched for billions of years regarding the birth of our solar system.
Increasingly, however, it looks as if the comets we see are anything but unspoiled. Instead, "there is good evidence that many of them are nearly burned-out hulks, with neither the size, mass, shape nor spin they might have had before entering the solar system," Jewitt said.
Still, "since comets are icy, they're not entirely cooked, and we may learn a lot regarding the formation of the solar system from chemicals trapped in their ice," he added.
Comets so close to the sun?
The main-belt comets are themselves a mystery. Until their discovery, researchers had largely supposed no comets could have lasted that close to the sun without getting baked away after a few centuries or millennia.
Dirt coatings on main-belt comets could have protected them from sunlight for billions of years. Every now and again boulders a yard or larger tumbling around the asteroid belt might hit these comets, uncovering their ice and triggering the plumes of gas and dust that got them discovered in the first place.
"We expect to soon find many hundreds or thousands of main-belt comets," Jewitt said.
Interstellar comets?
As our solar system formed, calculations predict the gravitational pull of the planets would have scattered 90 to 99 percent of all comets that once orbited the sun away toward the stars, never to be seen again. "If every star does that, you would expect some of their comets to come toward us, but no such object has ever been seen," Jewitt said.
Still, as astronomical telescopes and techniques improve, Jewitt remains optimistic that such interstellar comets will be detected fairly soon. These comets would prove quite distinctive, zipping at great speeds and following trajectories completely unlike the orbits our comets follow.
"We could see interstellar comets for the first time in the next few years," Jewitt predicted. "It would be great if we saw one, especially so if we had the wherewithal to launch a mission to one, to get samples and study the diversity of comets in an interstellar and galactic context. But we have to find one first."
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