|Early-morning fireball streaks across Colorado sky|
|Tauna Soch (Producer) |
DENVER - Several 9News viewers e-mailed us with accounts of what appeared to be a low-flying meteor.
One witness says he was walking through Bow Mar around 6:00 a.m. Tuesday and saw a shooting star, comet or something traveling from north to south at about 15 degrees off the horizon. It was travelling horizontal and according to witnesses was much larger than any shooting star they'd ever seen.
Another witness in Fort Collins saw a similar event around 5:50 a.m. It was described as a flying object which was believed to be a meteor. It was moving fast and straight from east to west and had a huge trail of fire behind it.
We contacted the Denver Museum of Nature & Science and workers there also received calls about the flash in the sky.
The Denver Museum of Nature & Science would like anyone who saw the event to record what they saw at a web site specifically designed for that.
|LOOK - UP IN THE SKY|
|Rocky Mountain News |
October 12, 2004
Meteorites are generally named after the region or town near where they were found. Here are the five Colorado meteorites that fell to Earth with someone watching.
• Denver, 1961. (This meteorite crashed through the roof of a warehouse in northeast Denver.)
• Cañon City, 1973 . (Crashed through a garage roof.)
• Elbert County, 1998. (Many witnessed a fireball; eventually three fragments were recovered.)
• Berthoud, Oct. 5, 2004, at 1:30 p.m. (Fell one day after other reports of a daylight fireball in Colorado.)
|Berthoud meteorite rocks scientists|
|By John C. Ensslin, Rocky Mountain News |
October 12, 2004
BOULDER - Out of a clear blue sky, a bit of space history as old as the solar system and no bigger than a softball slammed into the soft, wet earth beside a Berthoud family's home Oct. 5.
John Whiteis saw light and a little bit of dirt move. His wife, Meghan, saw a dark streak. Their 19-year-old son, Casper, heard something like this:
"We were kind of trying to figure out what we had just witnessed," said John Whiteis, a former auto mechanic and self-described Star Trek fan.
At first he thought it might be a piece of a passing plane. But there were none overhead.
Maybe a model rocket launched by a neighbor, they wondered. Nah.
Scientists say meteorites pepper the Earth's atmosphere daily, almost every hour. Most burn up as "shooting stars." Some land in sizes as small as a grain of sand.
The Whiteis family, however, witnessed only the fifth confirmed sighting of a meteorite hitting the ground in Colorado since 1924.
On Monday, the family gathered at the University of Coloradoto talk about their discovery along with a panel of geologists and astronomers.
Judging by their reactions, it was a close call as to which group was more excited by the find: the family or the scientists.
"Isn't this exciting?" CU geologist Steve Mojzsis gushed. "Thank you for bringing the meteorite in."
CU planetary scientist Nick Schneider d escribed his reaction when he first heard Casper Whiteis' rendition of how the meteorite sounded as it landed.
"I got chills up and down my spine hearing that description," Schneider said. "I get a zing from this rock."
"This came from outer space. It probably took a million years to get here," he added. "If you're feeling a little bit old, just come and touch this and it'll put things in perspective."
If not for some furniture the Whiteis family bought at an auction last weekend, this meteorite might have fallen to earth unseen.
It rained on Monday, so the furniture stayed in the vehicle. On Tuesday, John Whiteis was home from work early, so in came the furniture. And down came the meteorite.
It took the family about 25 minutes after impact to locate the meteorite.
A smooth black surface about the size of a golf ball peeked out from under the dirt.
John Whiteis turned back to the house to get a shovel. But before he could get there, Casper had grabbed a hammer and dug it out of the earth.
By then it was cool to the touch, said Casper, an aeronautics engineering student at AIMS Community College, who hopes to study at CU some day.
While meteorites have value to collectors and can fetch up to $1 a gram, the Whiteis family say their two-pound meteorite is not for sale. Instead they plan to let CU scientists study the rock and put it on public display.
Scientists at CU also hope to study the meteorite and compile other eyewitness accounts of any fireball sightings that day to determine its trajectory .
On Saturday, with permission from local property owners, scientists and volunteers hope to search up to four square miles of the area around the Whiteis home for other fragments.
|World's biggest meteorite field found in Egypt|
BEIJING, Oct. 12 (Xinhuanet) -- A team of French and Egyptian scientists say they've discovered the biggest meteorite field on Earth.
The meteorite site, with more than a hundred traces of crashed meteorites has been found in the region of the Egyptian-Lebanese border.
A spokesman of the French scientific research center CNRS, says the meteorite shower remains had hit the earth about 50 million years ago and covered the territory of 5,000 square kilometers.
Craters ranging from 20 meters to one kilometer in diameter have been created as a result of the clash. Meteorite remains are buried at an 80-meter depth.
Until recently, an Argentine meteorite field of 60 square kilometers has been considered the biggest in the world.
|Dinosaurs were in their prime when meteorite impact wiped them out|
|By Charles Arthur Technology Editor |
14 October 2004
|The common perception that dinosaurs were edging towards extinction when a huge meteorite wiped them out 65 million years ago is false, says a new study that claims the animals were in their prime when disaster struck. |
The variety of species existing around the end of the Cretaceous period suggests that they were diversifying at a remarkable rate, with an explosion of genetic diversity that was reflected in their success dominating the planet.
Scientists from the University of Rhode Island at Kingston, in the United States, established that at least 245 dinosaur genera - the "families" from which species emerge - lived during the late Cretaceous era, from 99 million to 65 million years ago.
They included some of the best known dinosaurs, such as tyrannosaurus rex and the three-horned triceratops.
Peter Sheehan, from the Milwaukee Public Museum, who took part in the research, told New Scientist magazine: "The lifestyles of dinosaurs became much more diverse. By the late Cretaceous, we have much more specialised animals."
The first dinosaurs evolved about 230 million years ago and were all much the same.
By the late Jurassic period, which began about 160 million years ago, they had produced about 40 different genera, or species families.
Then in the Cretaceous era which followed there was an e xplosion of dinosaur diversity, according to a new anal ysis of fossils from around the world.
Dr Sheehan said the diversity of plant-eating dinosaurs of the period was "absolutely breathtaking". For example, hadrosaurs evolved a duck-billed jaw filled with teeth for chewing vegetation, while the rhinoceros-like ceratopsians grew elaborate horns.
But the controversy over the dinosaurs' evolutionary path looks likely to continue: on Tuesday a paper published in the scientific journal Trends in Ecology and Evolution by Professor David Penny of Massey University in New Zealand and Dr Matt Phillips of Oxford University claimed the precise opposite - that birds and mammals began to "out-compete" dinosaurs about 80 to 90 million years ago, well before the end of the Cretaceous era.
"The combined evidence fro m fossils and molecules appears to support an expansion of birds and mammals, and a decline of pterosaurs and dinosaurs, starting many millions of years before the end of the Cretaceous," the scientists wrote.
What is not in doubt however is that there was a serious meteor strike on the Earth roughly 65 million years ago, in the Bay of Mexico. That is reckoned to have thrown up so much dust into the atmosphere that it cooled the planet abruptly, making it much harder for the cold-blooded dinosaurs to survive, and giving warm-blooded animals including mammals the evolutionary edge.
|Comment: Will there be a debate in several million years about whether or not "man" was at the height of his powers when the comet came and wiped most of him out?|
|Did the Celts see a comet impact in 200 B.C.?|
|The Chiemgau Impact Research Team |
October 14, 2004
|A new-found field of impact craters may mark the site of a recent comet strike. |
We have identified an exceptional field of meteorites and impact craters stretching from the town of Altötting to the area around Lake Chiemsee in southeastern Bavaria, Germany. While there are many meteorite "strewnfields" known around the world, few contain significant craters. The Chiemgau field, which falls within an ellipse 36 miles long and 17 miles (58 by 27 kilometers) wide, holds at least 81 impact craters ranging from 10 to 1,215 feet (3 to 370 meters) in size. Many more craters may lie hidden in heavily forested areas within the ellipse, and farming activities in the region may have destroyed others.
In autumn 2000, a group of amateur archaeologists working the area around Lake Chiemsee discovered pieces of metal containing minerals not found previously in the region. Werner Mayer, the independent scholar who led the amateur team, noticed that the material was associated with what appeared to be impact craters, most of which showed clear rims. In 2004, four other scientists joined Mayer to form the Chiemgau Impact Research Team: Kord Ernston, a geologist at the University of Würzburg; independent scholar Gerhard Benske; Michael Rappenglück, an astronomer with the Institute for Interdisciplinary Sciences in Gilching; and Ulrich Schüssler, a University of Würzburg mineralogist.
Geological evidence makes clear the site's extraterrestrial connection. Sandstone boulders and small, weathered rock fragments called cobbles in and around the craters are completely coated by silica glass, which requires unusually high temperatures. We believe the cobbles were superheated and ejected in the impact. We found bluish-gray, dark green, and black glass-like material in unusual shapes — such as teardrops and dumbbells — indicating rapid cooling and solidification during flight.
The peculiar minerals found throughout the site in clude the iron-silicon alloys gupeiite (Fe3Si) and xife ngite (Fe5Si3), both of which were identified in a meteorite discovered in the Yanshan Mountains of China in 1984. Gupeiite was also found in FRO 90036, a ureilite-class meteorite found in the Frontier Mountains of Antarctica, and related minerals were found in Dhofar-280, a meteorite that probably came from the Moon.
When did the impact occur? Archaeological finds in the area, as well as the ages of trees within the craters, tell us the impact occurred in historical times. The oldest tree we found rooted in a crater wall is at most 500 years old, and we found xifengite and gupeiite beneath the retaining walls of Burghausen Castle, which has been dated to the 15th century a.d. At another site, we unearthed impact-related minerals along with Celtic artifacts. The artifacts seem to have been strongly heated on one side. This pushes the earliest date for the impact to the late Roman period, between 480 b.c. and 30 b.c. Radiocarbon dates from ash samples we removed from layers in several craters are not yet available.
The growth patterns of Irish oaks slowed dramatically between a.d. 536 and 545, indicating a much cooler climate. Historical records refer to famine and a dimmed Sun during this period. Many have argued this so-called "dust-veil event" was the aftermath of a large (0.3 mile, or 500m) comet fragment exploding high in Earth's atmosphere. To date, no craters related to such an event have been found.
However, the rings also show slowed growth around 207 b.c. Roman authors wrote about showers of stones falling from the sky and terrifying the populace. In 205 b.c., because of these events, the Senate ord ered that a conical meteorite known as the Needle of Cybele (which had been worshipped in Asia Minor in connection with the fertility goddess Cybele) be brought to Rome. On the rim of the largest crater, named Tüttensee, archaeologists have found Roman relics from about a.d. 200. This, in addition to the heated coins from the late Roman period we found at the Chiemgau impact site, lead us to favor this early date.
We believe an asteroid or comet fragment exploded above southeastern Germany in the late Roman period. Our candidate impactor is a low-density object, perhaps something like the C-class asteroid 253 Mathilda. Astronomers believe Mathilda was once completely shattered but reassembled as a loose aggregate of material — that is, a rubble pile. Given the material we recovered and the length of the ellipse of scattered debris, we suggest the impacting body was more likely a comet fragment — rich in methane, ammonia, and water, with a relatively small fraction of rocky matter.
We estimate the projectile had a diameter of about 0.7 mile (1.1 km) and a mean density about 30 percent greater than water (1.3 g/cm3). It entered Earth's atmosphere at a speed of 27,000 miles per hour (43,000 km/h) and broke up at an altitude of 43 miles (70 km). The main mass of the projectile struck the ground at 2,200 miles per hour (3,500 km/h), releasing an amount of energy equivalent to 106 million tons of TNT. Based on the size distribution of the craters — the larger ones are in the southern part of the field, the smaller ones in the northern part — we conclude the meteoroid came out of the northeast and m oved southwest. Multiple fragmentation events may account for the cratered area's large size.
What would people on the ground have experienced? About 2 seconds after the strike, people 6 miles (10 km) away would have felt the ground shake as it would in a magnitude 6.0 earthquake. The air blast, arriving 30 seconds after impact, would have swept through at a speed of 500 miles per hour (800 km/h) and produced a peak pressure of about 1.4 atmospheres (142,000 Pa), easily collapsing buildings, especially wooden ones. Even from 10 km away, sound from the impact would have reached 103 decibels — loud enough to cause strong ear pain. Up to 90 percent of the trees would have blown over; the rest would have lost their branches.
We found a thin layer of ash in and between the craters. The for est beneath the blast would have ignited suddenly, burning until the impact's blast wave shut down the conflagration. Dust may have been blown into the stratosphere, where it would have been transported around the globe easily, so it may be possible to trace the event in ice cores from Greenland or Antarctica.
In any case, the impact undoubtedly had a major effect on the environment and people then living in the vicinity of Altoetting-Chiemgau. The region must have been devastated for decades. We are currently looking for gaps in the historical and archaeological records during the time we propose for the impact to better understand both the event itself and its cultural effects.
|Comment: So, another impact site has been identified. Curious. Did someone mention psychological preparation of the populace?|
|By JOEY HOLLEMAN |
Posted on Fri, Oct. 15, 2004
SHILOH — Hundreds of thousands of Midlands residents taking the southern route to Myrtle Beach each summer pass within a few miles of Woods Bay State Natural Area. Only a handful take the left turn and head for the park.
That's probably a good thing. Woods Bay in the summer is only for hearty souls with lots of bug repellent.
Between the first frost of fall and the first 90-degree day of spring, however, Woods Bay is the ideal place to spend an afternoon experiencing the intriguing geological phenomenon of the Carolina bay.
These oval-shaped, swampy depressions crop up throughout the Atlantic coastal plain, but they are as mysterious as they are common. Scientists aren't sure why the bays almost always have a northwest to southeast orientation. They are intrigued by the sand rims that usually form on the southeast and sometimes the northwest edges of the oval. They are perplexed how the bays formed in the first place.
One theory is that a meteor br oke into pieces, which impacted throughout the Southeast thousands of years ago. Folklorists like to claim the Carolina bays are dinosaur footprints.
Modern scientists can only say for sure that the ovals are disappearing under housing developments and shopping centers as the growing Southeastern population spreads out. That's why the state felt the need to buy and protect the 1,541 acres of Woods Bay straddling the Sumter-Clarendon county line in the 1970s.
The park opened in 1975 but never has drawn many people. In 2003-2004, Woods Bay ranked last among the 46 state parks in attendance, with only 2,124 visitors.
That frustrates park manager Geoff Akins, who has to remind himself what one of his supervisors told him about the park: "We're not popular. We're important."
One reason for the low attendance is the park is a long way from any large population area, nearly a half-hour drive from Florence or Sumter. Another is it's hard to get your hands around.
"One of the unfortunate things about the park is so much of it is inaccessible," Akins said. "I've had a lot of people walk around the nature trail and think they've seen the whole park."
|Comment: Ah, the site of yet another impact. Did anyone bring up the topic of psychological preparation of the populace?|
|Roman Comet 5,000 Times More Powerful Than A-Bomb|
|By John von Radowitz, Science Correspondent, PA News |
People living in southern Germany during Roman times may have witnessed a comet impact 5,000 times more destructive than the Hiroshima atom bomb, researchers say.
Scientists believe a field of craters around Lake Chiemsee, in south-east Bavaria, was caused by fragments of a huge comet that broke up in the Earth's atmosphere.
Celtic artefacts found at the site, including a number o f coins, appear to have been strongly heated on one side.
This discovery, together with evidence from ancient tree rings and Roman reports of "stones falling from the sky", has led researchers to conclude that the impact happened in about 200BC.
However the claim still needs to be verified by other experts.
The crater field was uncovered after amateur archaeologists working in the area found pieces of metal containing unusual minerals.
A team of geologists led by Kord Ernston, from the University of Wurzburg in Germany, went to the site and discovered evidence of a cataclysm that would have left the region devastated for decades.
Not only would trees and homes have been flattened for many mi les by the blast, but the local climate would have changed for years afterwards.
Tree rings show that vegetation growth slowed down in around 207BC, possibly because of the "nuclear winter" effect of dust blotting out the sun.
More than 80 craters were found in an elliptical area 36 miles long and 17 wide, ranging in size from 10 to 1,215 feet across. The largest, filled with water, now formed Lake Tuttensee.
Around the site the team found clues that suggested an impact from space, including rock heated into glass and minerals associated with meteorites.
The most likely cause was a low-density comet, 0.7 miles (1.1 kilometres) wide, that broke up at an altitude of 43 miles and fell in pieces to Earth, the scientists reported in Astronomy Magazine.
They wrote: "The m ain mass of the projectile struck the ground at 2,200 miles per hour, releasing an amount of energy equivalent to 106 million tons of TNT."
The bomb that destroyed Hiroshima at the end of the Second World War had an explosive force of just 20,000 tons of TNT.
The scientists gave a graphic description of what it might have been like to experience the impact.
"About two seconds after the strike, people six miles away (10 kilometres) would have felt the ground shake as it would in a magnitude six earthquake. The air blast, arriving 30 seconds after impact, would have swept through at a speed of 500 miles per hour and produced a peak pressure of about 1.4 atmospheres, easily collapsing buildings, especially wooden ones.
"Even from 10 kilometres away, sou nd from the impact would have reached 103 decibels – loud enough to cause strong ear pain. Up to 90% of the trees would have blown over; the rest would have lost their branches."
Forest beneath the blast would have ignited suddenly, and continued to burn until the shock wave blew the fire out, said the scientists.
The conflagration had left a thin layer of ash in and between the craters.
Roman authors at the time wrote about showers of stones falling from the sky and terrifying the local population.
Because of these events, the Senate in 205BC ordered that a conical meteorite known as the Needle of Cybele, which had been worshipped in Asia Minor, be brought to Rome.
"The impact undoubtedly had a major effect on the e nvironment and people then living in the vicinity of Altoetting-Chiemgau," wrote Ernston's team.
"The region must have been devastated for decades. We are currently looking for gaps in the historical and archaeological records during the time we propose for the impact to better understand both the event itself and its cultural effects."
Dr Benny Peiser, a leading expert on impact events from Liverpool John Moore's University, said the report should be treated with caution until more was known.
He said the date was speculative, and pointed out that asteroids or comets a kilometre wide struck the Earth on average only once every 500,000 years. Generally such a large impact would cause much more severe and obviously traceable damage.
"In short, this is an an intriguing find, but I remain sceptical for the time being," said Dr Peiser. "The impact cratering research community has not assessed these claims yet. That's what needs to be done next."
Comment: We can imagine that this part of Germany was not as highly populated in 200 BC as it is today. Imagine such an explosion over a city such as New York, London, Tokyo, or New Delhi?
Another such event occurred about 740 years later, again in Europe. It may well have been the cause of what has come to be known as The Dark Ages. We know, as well, of the Tunguska blast in 1908 over a portion of Siberia, a blast so great that people in London could read their newspapers at night by its light. And these events were relatively small.
And what effect would it have on an already chaotic climate?
|What is the chance of an asteroid hitting Earth and how do astronomers calculate it?|
Perry A. Gerakines, an assistant professor in the department of physics at the University of Alabama at Birmingham, explains.
We have extensive evidence that Earth has already been hit by asteroids many times throughout history-the most famous (or infamous) example is probably the asteroid or comet that created the Chicxulub crater in the Gulf of Mexico and may have contributed to the extinction of the dinosaurs at the end of the Cretaceous Period 65 million years ago. A more recent but less devastating example, called the Tunguska event, occurred in 1908, when a meteor or comet exploded over the wilderness of Siberia, damaging farmland and leveling trees for miles around. Because most of the earth is covered by oceans, there may also be many small impacts that go unnoticed.
There are thousands of small bodies that we call asteroids or meteoroids in orbit aroun d the sun. Many of these objects are called near-Earth asteroids (or NEAs) because they have orbits that repeatedly bring them close to, or intersect with, Earth's orbit.
Although the odds of any one particular asteroid ever impacting Earth are quite low, it is still likely that one day our planet will be hit by another asteroid. At the current rate of impacts, we would expect about one large asteroid to impact Earth every 100 million years or so. For that reason several programs, such as the Lincoln Near-Earth Asteroid Research (LINEAR) project at the Massachusetts Institute of Technology, have been undertaken around the world to discover and monitor potentially Earth-threatening asteroids.
When a new asteroid is discovered, astronomers analyze it to determine whether its orbit around the sun could bring it close to the Earth. They take successive images of the asteroid over the course of days after its discovery in order to predict its probable orbital path for the near future. The predicted orbit is then compared to the orbit and position of Earth to check for any times when they might pass close to each other.
Although scientists can calculate a most-likely orbit from these early observations, each single observation of the asteroid's position contains some uncertainty. Most asteroids are small objects, a few meters to a few tens of meters across, and even the resolving power of a large telescope cannot determine their positions exactly. The uncertainties in an asteroid's position lead to uncertainties in how well we can determine its speed and direction of travel. A s a result, a large number of possible orbits for an asteroid can be predicted within these windows of uncertainty.
Careful computer simulations are used to calculate the future orbital path of the asteroid, with randomly chosen initial positions and velocities that fall within the margin of error of the telescopic observations to date. A large number of these simulations are generated for each asteroid. The probability that any particular one will actually hit Earth is given by the fraction of the extrapolated paths that leads to an impact. For example, if one million different possible orbits are calculated, and one of those leads to an impact, then we say that the odds of the asteroid hitting our world are one million to one.
The uncertainties in an asteroid's orb it are greatest in the hours just after its discovery, and thus the calculated probability of an impact also tends to be the highest at these times. As we monitor an asteroid over the course of the weeks or months that follow, its orbit becomes more and more certain, and we become more knowledgeable about its position at a given date in the future. We can then rule out many possible paths it may take. In most cases, monitoring the asteroid over a few weeks quickly leads to an impact probability of very nearly zero.
Comment: The above article is an answer to a question posed on the web site of the Scientific American. It shows that the awareness of the danger of an asteroid impact is beginning to be felt in the population while at the same time, the population is told to not worry, a major event only happens once every 100 million years.
Unfortunately, as the explosion at Tunguska shows, there is no need for an impact for there to be devastation on Earth. Explosions above the surface of the planet can been catastrophic. The study of tree rings shows the possibility of quite frequent impacts having deleterious effects in local regions, such as the impact in Germany that occurred about 200 BC (that we discussed yesterday) and the one in Europe in about 540 BC that brought on the Dark Ages. So it is misleading to throw out the number "100 million years", as if that means we have nothing to be worried about.
The number of sightings of fireballs has been quite regular in the last couple of years. Some of them may not make it into the press. At the most, they appear in local papers and aren't picked up for national or international syndication. We think there is evidence to show that such visitors are cyclic, and that their return shouldn't be long.
|"Fireball in sky" clue to blast|
|Neal Keeling and Rashid Raz aq |
Thursday, 14th October 2004
TWO "fireballs" in the sky could be clues to the massive mystery explosion which rocked part of Greater Manchester yesterday.
They were seen by midwife Jeanette Vagg as she drove home just minutes before the huge bang was heard.
And an expert at Jodrell Bank Observatory in Cheshire believes the cause could be a bolide - a meteor between the size of a hazelnut and a tennis ball.
"When it hits the atmosphere, it shatters," said astronomer Ian Morison. "A loud explosion would be heard and the debris could break into a million little bits. It seems like a reasonabl e explanation for what happened."
Other theories for the massive noise in the Salford area include the an unlicensed industrial firework and a build-up of flammable gases in disused mine workings.
But Jeanette is convinced that meteorites are the answer.
Jeanette, who works at Trafford General, said: "I was driving home through Urmston towards Stretford and I saw them in the sky.
"They were black at the bottom with flames coming off them in a line. They were falling and one was a bit higher than the other. My first reaction was to think 'I hope they're not bombs'. I drove a bit further and looked again, but they had gone."
As reported in yesterday's MEN, dozens of people called the police and fire service after hearing the blast at about 7.30am.
Chief Supt Brian Wroe of Salford police said: "The industrial firework is one of several possible explanations, as is an underground explosion.
"Officers have met with residents in the Old Clough Lane area of Worsley where we first received reports of an explosion. We have also spoken to the fire service, the gas companies and the local authority and not been able to find any rational explanation.
"We are keeping an open mind as we haven't been able to find any evidence of damage or destruction."
The blast was heard by people in Chorlton, Farnworth, Walkden, Worsley and Pendlebury. But police and the fire service have been unable to identify the source despite searching the area.
The investigation has now been closed unless members of the public suggest new lines of inquiry.
Earthquake experts today denied that a quake could have taken place in Greater Manchester.
Experts from the British Geological Society launched an investigation, but said that there was no evidence of any earthquake activity in the region.
|Orionid Meteor Shower to Peak Wednesday Night|
|Brian Handwerk |
for National Geographic News
October 18, 2004
Halley's co met won't return until 2061, but pieces of the celestial body are streaking across the sky. The heavenly show, known as the Orionids meteor shower, peaks Wednesday night, when sky-watchers may observe two dozen meteors per hour.
Though the comet remains distant, Earth is passing through the comet's ancient debris field—with dramatic results.
"Over time comets leave a trail of debris along their orbits," explained Kelly Beatty, executive editor of Sky and Telescope and editor of Night Sky magazine.
Each time a comet orbits the sun, the star's heat strips comets of dust and ice. Scientists believe that Halley's comet sheds some 20 feet (6 meters) of dust and ice particles on each pass.
Earth passes near Halley's cigar-shaped orbit debris field twice each year: the Orionids shower fall in October, the Aquarids shower in May.
"What we see is not the particle burning up," Beatty said. "What we're really seeing is the particle transferring all that energy to the air molecules along its path and causing them to become superheated to the point that they are incandescently hot."
Meteor particles are among the smallest celesti al objects that can be seen by the human eye.
"For anyone who has eaten a bowl of Grape Nuts, the little nuggets in there are a pretty good match in size, shape, density, and even color of what a typical meteor particle looks like from space," Beatty said. [...]
|Could Multiple Meteor Impacts Have Killed the Dinosaurs?|
The Chicxulub meteorite impact is largely credited with the extinction of 50 percent of the world's species, in cluding the dinosaurs. But could there have been more than one meteorite impact 65 million years ago?
Astrobiology Magazine -- Rather than a single meteorite impact 65 million years ago, could Earth have been hit with a scattershot of several rocks from space?
It may have happened before. There is evidence that about 35 million years ago, at least five comets or asteroids collided with Earth. If the effects of a single large meteorite impact seem overwhelming, imagine how life on Earth would reel from a barrage of rocks from space.
One way such impact clustering happens is to have a single bolide break up as it approaches a planet. The comet Shoemaker-Levy 9 provides a recent example. Before striking the planet Jupiter in 1994, the comet was torn into 21 different pieces by Jupiter's immense gravity. These fragments struck Jupiter over 5.6 days, some creating large fireballs as they entered Jupiter's vast gaseous atmosphere.
Earth's gravity is no where near as powerful as Jupiter's, so the same scenario would not happen to Earth. Yet many asteroids are thought to be rubble piles, loosely bound by gravity, and such an asteroid could rip apart as it approached our planet.
But if an asteroid "rubble pile" broke up before it entered Earth's atmosphere, the pieces would only result in one crater, or at most two, because most of the pieces would fall into the same hole.
"Once such a rubble pile enters Earth's gravity it's too late," says Christian Koeberl, a geochemist at the University of Vienna in Aust ria. "It would only get into the attraction field of Earth's gravity a few hours before it hits at best, and this is not time enough to spread it out appreciably."
However, having an asteroid break up as it approaches Earth is not the only way to end up with multiple craters.
Within the asteroid belt that orbits the sun between Mars and Jupiter, collisions between asteroids sometimes occur. The resulting fragments can then rain down on Earth. Simon Kelley, a geologist at the Open University in England, says that such a collision occurred 470 million years ago, and many of those fragments traveled to Earth. In fact, some of the fragments still are impacting Earth today.
A similar shower of fragments can come from a collision within the Oort cloud, a comet-filled region in the outer-most portion of the solar sy stem. Kelley says such a cometary shower may be responsible for the cluster of impact craters dated to be 35 million years old, including two of the largest impact craters on Earth: the 100 kilometer Popigai crater in Siberia, and the 90 kilometer Chesapeake Bay crater off the shore of Maryland. This cometary shower is thought to have lasted for 2 to 3 million years.
Looking over the Planetary and Space Science Centre's Earth Impact Database, several of the crater dates overlap. Much of this overlap reflects the limitations of current dating techniques, where ages can't be narrowed down further than hundreds of thousands of years. But it is possible that some of the craters point to a multiple impact scenario.
The Boltysh crater in the Ukraine may be proof that multip le impacts occurred during the Cretaceous-Tertiary (K-T ) extinction. Kelley has dated the crater to be about 65 million years old.
The Boltysh crater had previously been assigned ages ranging from 88 million to 105 million years old, a variation that arose due to the different dating methods used. Kelley used Argon-Argon dating to determine the correct age for the crater. The crater rocks melted in the heat of impact, and when they cooled they trapped argon out of the air. Different isotopes of argon decay at different rates, so by measuring the ratio of argon isotopes, Kelley was able to estimate when the rocks melted, within a margin of error of plus or minus 600,000 years.
The margin of error prevents scientists from saying Boltysh was definitely part of the same meteorite strike as Chicxulub. And Kevin Pope of Geo Eco Arc Research points out that while Chicxulub has been linked directly to the K-T boundary and extinctions by the stratigraphy of its ejecta, the same is not true for Boltysh.
"Craters the size of Boltysh form every few million years, so the fact there is a crater this size close to the boundary is no surprise," says Pope.
The Boltysh crater measures only 24 kilometers in diameter - compared to Chicxulub's nearly 200-kilometer-wide monster - so even if the smaller meteorite that made this crater hit around the same time as Chicxulub, its effects wouldn't have been as catastrophic.
But if Boltysh did occur around the same time as Chicxulub, it could aid in our understanding of the K-T extinction event. Craters can act as time capsules, preserving information about the environment at the moment of impact. Comet Shoemaker- Levy left enormous scars on Jupiter. Credit: NASA
Like Chicxulub, the Boltysh crater is buried underground. But while Chicxulub filled with seawater, the Boltysh crater became a fresh water lake. Kelley is writing a paper with Dave Jolley at the University of Sheffield on the microflora and fauna they have found in the Boltysh crater fill. They hope to determine how rapidly life recovered in the vicinity of the impact, and how that recolonization occurred.
As for other K-T impact craters, Kelley notes that the record is very poorly dated. He plans to study other craters, currently dated to be from the Devonian (around 380 million years ago) to the Eocene (34 million years ago), to see if their ages are accurate. By determining the correct dates f or impact craters, scientists will be able to better understand how often multiple impact events have occurred in the past.
So do multiple impacts play a role in mass extinctions? Kelley says that as far as we know, they don't. For instance, Kelley says there is no evidence that the barrage of comets 35 million years ago led to a mass extinction event.
"The effects would have been truly devastating locally, but they didn't amount to global catastrophes," says Kelley. "You can argue that minor extinctions are associated, but not a K-T-like event."
A single large meteorite impact like Chicxulub may be more harmful to life than a cluster of several smaller meteorites or comets spread out over a million years or less. Yet determining why certain species die out can often be difficult. Extinctions are a natura l part of the cycle of life, and may occur due to a whole host of interrelated factors, including competition for food, climate change, and even sea level change. Perhaps tossing a few meteorites into the mix also can upset the scales, tipping some species too far off balance to recover.
|Comment: We have been discussing the possibility of meteor impact on this site for many years, specifically the possibility of an impact caused by a disruption in the Oort cloud sending a swarm of rock towards the inner solar system and Earth.|
|Solar Cycle Update|
|October 18, 2004|
Six … long … years.
Solar physicist David Hathaway has been checking the sun every day since 1998, and every day for six years there have been sunspots. Sunspots are planet-sized "islands" on the surface of the sun. They are dark, cool, powerfully magnetized, and fleeting: a typical sunspot lasts only a few days or weeks before it breaks up. As soon as one disappears, however, another emerges to take its place.
Even during the lowest ebb of solar activity, you can usually find one or two spots on the sun. But when Hathaway looked on Jan. 28, 2004, there were none. The sun was utterly blank.
It happened again last week, twice, on Oct. 11th and 12th. There were no sunspots.
"This is a sign," says Hathaway, "that the solar minimum is coming, and it's coming sooner than we expected."
The blank sun on Oct. 11, 2004, photographed by the ESA/NASA Solar and Heliospheric Observatory.
Solar minimum and solar maximum--"Solar Min" and "Solar Max" for short--are two extremes of the sun's 11-year activity cycle. At maximum, the sun is peppered with spots, solar flares erupt, and the sun hurls billion-ton clouds of electrified gas toward Earth. It's a good time for sky watchers who enjoy auroras, but not so good for astronauts who have to be wary of radiation storms. Power outages, zapped satellites, malfunctioning GPS receivers--these are just a few of the things that can happen during Solar Max.
Solar minimum is different. Sunspots are fewer--sometimes days or weeks go by without a spot. Solar flares subside. It's a safer time to travel through space, and a less interesting time to watch polar skies.
Hathaway is an expert forecaster of the solar cycle. He keeps track of sunspot numbers (the best known indicator of solar activity) and predicts years in advance when the next peak s and valleys will come. It's not easy:
"Contrary to popular belief," says Hathaway, "the solar cycle is not precisely 11 years long." Its length, measured from minimum to minimum, varies: "The shortest cycles are 9 years, and the longest ones are about 14 years." What makes a cycle long or short? Researchers aren't sure. "We won't even know if the current cycle is long or short--until it's over," he says.
But researchers are making progress. Hathaway and colleague Bob Wilson, both working at NASA's Marshall Space Flight Center, believe they've found a simple way to predict the date of the next solar minimum. "We examined data from the last 8 solar cycles and discovered that Solar Min follows the first spotless day after Solar Max by 34 months," explains Hathaway.
The most recent solar maximum was in late 2000. The first spotless day after that was Jan 28, 2004. So, using Hathaway and Wilson's simple rule, solar minimum should arrive in late 2006. That's about a year earlier th an previously thought.
The next sola r maximum might come early, too, says Hathaway. "Solar activity intensifies rapidly after solar minimum. In recent cycles, Solar Max has followed Solar Min by just 4 years." Do the math: 2006 + 4 years = 2010.
By that time, according to NASA's new vision for space exploration, robot ships will be heading for the moon in advance of human explorers. If Hathaway and Wilson's prediction is correct, those robots will need good shields. Solar flares and radiation storms can damage silicon brains and electronic guts almost as badly as their organic counterparts.
For now, says Hathaway, we're about to experience "the calm before the storm." And although he's a fan of solar activity--what solar physicist isn't?--he's looking forward to the lull. &quo t;It'll give us a chance to see if our 'spotless sun' method for predicting solar minimum really works."
Solar Max will be back soon enough.
|Unseen comets may raise impact risk for Earth|
| Mark Peplow |
18 October 2004
The Solar System could be teeming with almost invisible comets, according to some astronomers' calculations. If the y are right, such extra comets would significantly increase the risk of a catastrophic impact with Earth.
These objects have never been observed, but the astronomers argue that 'dark comets' provide a likely explanation for an astronomical puzzle: we can only see a tiny fraction of the comets that theory predicts.
Astronomers think that many comets come from the Oort cloud, a field of billions of icy objects that lies up to 100,000 times farther away from the Sun than the Earth does and marks the outer boundary of our Solar System. The icy objects are sometimes driven towards the Sun by gravitational tides generated by the shifting masses of stars in our Galaxy. When this happens they become comets, orbiting the Sun every 20 to 200 years on paths that lie at an angle to the planets' orbits.
Given the s ize of the Oort cloud, astronomers have calculated that there should be about 3,000 comets in these orbits, 400 times more than are actually observed.
The common explanation for this discrepancy is that the comets quickly disintegrate into smaller lumps after just one or two orbits, says Bill Napier, a recently retired astronomer who worked at the Armagh Observatory, Northern Ireland. But his mathematical model now suggests that, if this were true, the debris should cause many more major meteorite showers on Earth than we see, perhaps up to 30 every year.
In a paper to be published in the Monthly Notices of the Royal Astronomical Society1, Napier concludes that the predicted comets are out there after all; we just cannot see them.
Little fluffy clouds
Napier worked with Chandra Wickramasinghe, an astronomer at Cardiff University in Wales, to explain the comets' invisibility. Wickramasinghe has suggested that Sedna, the most distant body identified in our Solar System, could have an orbiting twin that is dark, fluffy and made of tarry carbon compounds (see "Sedna 'has invisible moon'").
As Sedna may be a member of the Oort cloud, Napier thinks that other members of the cloud could be equally dark. Once ejected, the tarry comets would simply suck up visible light, he says, remaining cloaked in darkness. "Photons go in, but they don't come out."
"It's an intriguing possibility," says Alan Fitzsimmons, an astrophysicist at Queen's University of Belfast in Northern Ireland. "But while we have seen dark objects before, Bill is proposing something much, much darker tha n anything we've ever detected."
NASA's Stardust probe, which is bringing back samples of dust from the comet Wild 2, lends some support to Napier's idea. In June this year it reported finding lots of tarry carbon compounds spraying from the comet2.
The dark comets would present a major challenge to astronomers searching the skies for objects that might collide with the Earth. "They're so black you can't see the damn things," says Napier. "These things will just come out of the dark and hit you with no warning. It looks as if we're dealing with a substantial impact hazard that people haven't clicked into yet."
However, although they reflect almost no visible light, the dark comets should give out a tiny glow of heat, visible as infrared radiation. The infrared Spitzer Space Telescope, which has been operating from Earth orbit for just over a year, has not seen any dark comets. But this could be because it focuses on very small, distant parts of the sky, says Napier.
Fitzsimmons disagrees, saying that if these objects existed in the numbers proposed by Napier, either Spitzer or near-Earth object surveys such as Spacewatch, based at the University of Arizona in Tucson, would have picked them up by now.
A new space telescope might provide the answer. Earlier this month, NASA announced that it would launch an orbiting infrared telescope called the Wide-field Infrared Survey Explorer (WISE) in 2008, which will map much wider areas of the sky. Given enough time, it should be able to detect the dark c omets, says Napier.
|Comment: How coincidental that NASA has launched an infrared telescope capable of detecting these dark comets... In any case, one should remember that there have been visible NEO's in recent times that were not detected at all until they had zipped past the Earth.|
|Theory of Relativity Evidence Found|
| By Guy Gugliotta |
Washington Post Staff Writer
Friday, October 22, 2004; Page A03
Health/Science/Tech By measuring variations in satellite orbits, scientists have found the first direct evidence of one of the hallowed tenets of Albert Einstein's theory of general relativity -- that the Earth and other large celestial bodies distort space and time as they rotate.
Researchers reporting yesterday in the journal Nature said improved satellite data had enabled them to show the effect known as "frame-dragging" with a degree of precision never previously possible.
"We impro ved our accuracy by orders of magnitude," said geodesist Erricos C. Pavlis of NASA's Goddard Space Flight Center in Greenbelt and the University of Maryland at Baltimore. "In a while, we should be able to do even better."
Scientists expect that the results of the experiment, by Pavlis and Ignazio Ciufolini of Italy's University of Lecce, will be reinforced by NASA's ongoing Gravity Probe B, a satellite mission designed to measure frame-dragging and another Einsteinian effect by a different method -- calculating gyroscope deviations over time.
"Gravity Probe B is less systematic, but will provide higher accuracy -- within a margin of error of less than 1 percent," said Michael Salamon, NASA's discipline scientist for fundamental physics. "What this research [ye sterday's report] means is that GPB may not in fact pro vide the first direct evidence of frame-dragging."
In the early 20th century, Einstein theorized that the gravity of large bodies such as the Earth distorts space and time, much the way a bowling ball would stretch a rubber sheet held aloft on all four corners.
Frame-dragging occurs, he said, because the Earth's rotation pulls space-time along with it. Salamon likened the effect to dipping a spoon into a cup of honey and turning it. Close to the spoon the honey twists, but the effect dissipates with distance.
Scientists have wanted to prove Einstein's theory since the dawn of the space age. Gravity Probe B, conceived more than 40 years ago, is measuring frame-dragging from a satellite by focusing a telescope on a distant "guide star" and measuring how the a xes of gyroscopes deviate from their original positions pointing directly at the star.
Pavlis and Ciufolini used satellites in a completely different way. They closely tracked the orbits of LAGEOS and LAGEOS2, passive satellites covered with "retroreflectors" that reflect laser beams from ground stations, giving precise measurements of distance from the station to the satellite.
The satellites' orbits are slightly distorted -- not perfectly circular or elliptical -- because irregularities in Earth's surface jog them. But even after subtracting this surface-caused "noise," the researchers were still left with orbits that deviated slightly from what they should have been. The difference, they said, reflected frame-dragging.
"The satellite orbits ar e not perfect because the Earth is not perfect," S alamon said. "So subtract them out, and what you're left with are the effects of space time. The results are better with two satellites, and three would have been even better."
The key to the experiment's success was better data on Earth's gravity field -- a better map of the Earth-induced orbital distortions. This information, collected by another new satellite, enabled Ciufolini and Pavlis to shrink their margin of error dramatically from the 20 percent they obtained from an earlier attempt.
"There was a tremendous amount of criticism then, and a lot of people said 20 percent was on the edge of being acceptable," Salamon said. "This result, between five and 10 percent, is a lot cleaner."
|Meteors visible in Knox County|
|Published: Monday, October 25, 2004 07:17 AM|
MOUNT VERNON - Several Knox County residents reported seeing a mysterious blue glow in the sky last night. It was actually a meteor shower.
Sarah Graham and Carri Yost, Mount Vernon Nazarene University students, witnessed the shower about 11:15 p.m. The students were traveling on Lower Gambier Road near Ohio 229 when, according to Graham, The atmosphere turned blue, th en there was a little split in the sky and an orange color appeared. It happened very quickly.” A 9-1-1 dispatcher confirmed that it was indeed a meteor shower over Licking County.
According to NASA, on any night, at any location, a few meteors can be seen each hour. These are called sporadic meteors, or simply sporadics. Occasionally, though, intense meteor displays fill the sky with tens, hundreds, or even thousands of meteor trails. These displays are called meteor showers. Many meteor showers can be predicted, as they repeat every year when the earth passes through the path of a comet. The bits of debris left behind by the comets, most no larger than a grain of sand, create a spectacular light sho w as they enter the earth’s atmosphere. [...]
Comment: Hmm... the dispatcher seems pretty certain that the "mysterious blue glow" reported by several residents was part of the Orionid meteor shower, and perhaps it was. However, should we take their word for it just because they work for 9-1-1 dispatch?
Do meteor showers normally emit a mysterious blue glow?
Often when we witness an anomalous or unexplained event, our conscious mind automatically tries to classify it according to what is known or generally accepted by consensus reality.
Rather than face the unknown with an open and inquiring mind, we tend to pi geonhole and classify everything we experience to conform with our preconceived ideas. It is much more comfortable that way.
If this story was all we had to go by, one would be left with the impression that the "mysterious blue glow" was not much of anything at all.
Fortunately, there are others who report the facts.
|Reports of Meteorite in Licking County|
|WBNS TV |
October 25, 2004
Was it a bird? A plane? A lot of people are wondering what lit up the sky around 11:15 p.m. on Sunday.
The mysterious blue light was seen flying over Ohio, Indiana and Pennsylvania. The fireball was left by Halley's Comet and was part of a meteor shower that peaked last week.
All those who saw it say it really was a sight.
Judy Spaulding says, "It was just amazing. We thought it was lightning but it couldn't have been it was blue an d it lit up the whole the sky. It was weird. That's all I can say. It was weird."
"You think maybe UFO. You never know with everything that going on," says Carl Lovingshimer.
An amateur astronomer in Hocking County in southeast Ohio says a fireball lit up the sky for about two seconds and then left a trail of light and smoke that lasted for several minutes.
He describes fireballs as large, bright meteors.
Craig Kelly from COSI says, "When the earth plows through that, that's when you see a meteor show. This time it was hitting the Earth at 66 kilometers per second."
It is unknown where the meteor landed. It is believed to have landed somewhere on earth, but no reports just yet.
Comment: From this report we find out it was most likely a meteor, and perhaps even a meteorite. Still, the writer. having no other explanation, ascribes the fireball to originating from Halley's comet as part of the same meteor shower, which may or may not be true, and also falls into the "publicly acceptable definitions" category.
What is suppressed by mainstream science and media, and would be frightening to contemplate for most people, but seems more likely based on the scientific evidence, is that the rash of meteorite sightings over the last little while, are the result of a periodic meteor and asteroid swarm that passes through our solar system every few hundred thousand years causing havoc and destruction in it's path.
If one thing seems certain, what we are seeing now is just the beginning of a much larger event.
Now for some eye-witness reports...
|Viewer Descriptions Of Flash In Sky|
|NBC 4 |
October 25, 2004
COLUMBUS, Ohio -- The following are viewer e-mails to NBC 4 after they saw a bright flash of light in the sky Sunday night in Central Ohio.
*At 11:20 p.m. over in the sky northeast of Pataskala Ohio, we just saw a strange flash of light, it was blue-green, it lit up our street and then orange smoke (was) in the sky.
*I live off of Holt Road in Grove City. As I was driving home this evening around 11:15 p.m., I saw a bright flash of light, looked up and saw what looked to be a streak of fire that quickly dimmed. At first I thought the flash of light was lightni ng, but then I saw the streak in the sky. I've seen "shooting stars," but this was extremely bright and I had never seen one "burning out" so clearly before.
* I was on I-270 driving and at approximately 11:18 p.m., I saw what was probably a large meteor that looked like it was traveling east and lit up the sky.
* My husband and I were driving in Pickerington toward Baltimore and we saw something amazing in the sky. It looked like something exploded, making a white flash, then the entire sky was glowing bright blue. We saw something that seemed to be burning, falling in the direction of I-70. The trail of the object was also glowing orange, and then it turned to smoke and dissipated.
*There was a flash of blue light in the sky, like an explosion It was bright enough to light up my block.
*I was laying in bed last night looking out my bedroom window when I saw the blue light just beneath the crack in my window shade. It was like a turquoise-blue light lighting up the sky. The sight reminded me of a light bulb that had just burnt out after you turn on the switch except it was a pretty blue color.
*I was on I-71 North last night, maybe 40 minutes outside of Columbus, when the whole sky lit up a bluish-green color and then there was a giant flash of white. It looked like a firework, but my friend and I knew it was too far away to be a firework. We thought maybe it was a meteor or even an alien spacecraft. It was quite beautiful
*I was returning home from a concert sometime aft er 11 p.m. last night. As I opened the front door to my house, suddenly the whole sky seemed to light up for a brief instant in a bright shade of blue. I turned around to face the eastern sky, and I saw in the distance a bright blue ball of light and a trail of white and yellow "sparks" emanating from it, streaking across the sky. It looks like an offshoot from a fireworks display, only clearly at a much higher altitude than fireworks -- and no sound. As the "sparks" trailed off, they left a faint, hazy glowing trail in the sky for several minutes. I opened the door and called to my wife to come and see, but by the time she made it out, the trail had nearly vanished.
*I saw it last night as I was standing out talking to a friend. It did not "streak across the sky." It dropped from the sky down.
*First of all there was the bright blue flash that lit up the whole sky area, I was facing slightly away from it so it was in the edge of my sight when it exploded, but I turned quickly to it. I saw something twirling down leaving a glowing trail like no other meteorite I have ever seen. I then saw something large drop below it very fast but not like a meteorite.
*The stream was not sparking, it was glowing, as seen from here. It was obviously glowing residue. It did not fade away as I have seen all other meteorites fade. It gradually spread out and the glowing got dimmer. If you did not know it was there and looked in the sky you might not see it. Know ing it was there I kept watching. You could see the str eam slowly spreading out with the spiraling route seen easier.
* At no point did I think, not now do I believe it was a meteorite, It had the appearance of either a plane exploding then falling from the sky, Or a space capsule exploding then falling from the sky in a swirling motion as some planes do when they lose control suddenly and crash.
*The stream looked like the space capsule that exploded after take off, and spiraled up, but this was in reverse.
*I saw the light in Galloway. The only reason I did was because my dogs started going crazy, very agitated and barking right before it happened and I got up to put them outside. It looked like a spotlight from a helicopter it was so brigh t, only it was blue.
*I am a resident in Athens, Ohio. I saw the light last night when I was leaving my friend's house at 11:21 p.m. to be exact. It did undoubtedly leave the sky bright blue for a split second. However, it burned, literally, red like it was on fire and left a trail of smoke behind it. The smoke lingered in the air for some time after it disappeared.
*I walked outside Sunday onto the porch around 11:15 p.m. and happened to be looking toward the eastern sky. That's when I saw it the object in the sky. The sky lit up like a welder's torch and the entire neighborhood lit up like a silent flash of lightning. The object was traveling northeast as it exploded instantly leaving a broad long trail of glowing ember s that remained visible for nearly 20 seconds. It was a clearly visible over porch lights and a bright moon. I consider myself lucky to have seen such a magnificent show.
*I live in southern Ohio, in Jackson County, and I saw the meteor. It came from the east, lighting up the sky as it traveled, leaving a long, bright trail. It disappeared over the northern horizon. The light was bright enough that the dogs outside started barking.
*The meteor last night provided a little extra "scare" for me and three of my friends. We had just gotten out of "The Grudge," a new scary movie with Sarah Michelle Gellar, and we were all a little spooked. As we were walking out to our car there was a sudden booming sound and the entire sky lit up. We looked up and saw a streak across the sky. Everyo ne in the parking lot just stopped what they were doing and looked up to the sky. I think everyone got a little Halloween spook out of the meteor.
|Comment: So much for space dust.|
|Day from hell may have killed off dinosaurs|
| By Alistair Bell|
Wed 27 October, 2004 13:03
YAXCOPOIL, Mexico (Reuters) - One minute you're a big T-Rex, the next you're toast.
Challenging conventional theory, new scientific research suggests the dinosaurs may have been scorched into extinction by an asteroid collision 65 million years ago that unleashed 10 billion times more power than the Hiroshima nuclear bomb.
Earth's temperatures soared, the sky turned red and trees all over the planet burst into flames, said atmospheric physicist Brian Toon of the University of Colorado.
Among the few survivors would have been animals living in water or burrowed in the ground like turtles, small mammals and crocodiles.
"Essentially, if you were exposed you were broiled alive. That is probably what happened to the dinosaurs. They were big creatures that didn't have anywhere to hide," said Toon.
Scholarly debate over how the dinosaurs died is fierce and the theory put forward by Toon and others adds one more twist to the greatest forensic mystery of all time.
Despite opposition from some scientists, the idea that the dinosaurs were killed by an asteroid that slammed into Mexico's Yucatan peninsula has won general acceptance since it was first mooted in the early 1990s.
Under that argument, academics say the giant reptiles mostly froze or starved to death when a huge cloud of particles kicked up by the meteorite blocked the world's sunlight for months.
But Toon, the co-author of a study published in the Geological Society of America Bulletin in May, reckons the dinosaurs' end was even more dramatic .
Creatures living near ground zero would have been vaporized immediately while those in the Caribbean area and southern United States would have drowned in 330-feet-high (100-metre) tsunamis when the asteroid impacted near today's Gulf of Mexico shoreline at a speed of 33,750 mph (54,000 kph).
Then, a column of red-hot steam and dust soared thousands of miles (km) into space and most of it fell back toward Earth within a few hours, turning the heavens into hell.
"The entire sky would be radiating at you. It would be like standing next to a giant fire; you'd be burned very severely," Toon said, whose research is based on mathematical and computer models.
Land dinosaurs all around the world perished from the intense heat of several hundred degrees Fahrenheit, said Toon.
He agrees with other scientists that the dust cloud later cooled and blocked out the sun, but says the land dinosaurs were already history by that time.
The darkness finished off many of the remaining marine reptiles and fish by killing plankton and disrupting the food chain, said Toon. [...]
|Comment: Just think of all the recent fireball sightings. Then think about all the rumored and confirmed underground military installations. So you see, there's nothing to worry about... While we are all being roasted alive and subsequently deep frozen, the fascists that control our planet will be safe and sound under a couple thousand feet of rock - and thus humanity will go on.|
|‘Invisible’ comet could hit earth, scientists claim|
Research conducted by a Cardiff University astronomy scientist suggests that a comet colliding with earth is actually more likely than was previously believed.
Professor Chandra Wickramasinghe, Honorary Professor Bill Napier and research student Janaki Wickramasinghe of Cardiff University’s centre for Astrobiology believe that some comets are not visible using current astronomical scanning equipment.
They argue that if this is the case, international programmes designed to detect near-earth asteroids, and ways to reduce the worst effects of them colliding with Earth may need to be urgently reviewed.
Professor Wickramasinghe said, "It’s possible that we are missing many of these Earth-threatening objects and we need to think again ab out mitigating strategies - some of which assume decades or centuries of warning before impact."
The team has found that the surfaces of inactive comets, if composed of loose, fluffy organic material like cometary meteoroids, develop such small reflectivities - they appear invisible. The near-earth objects may therefore be dominated by a population of fast, kilometres-wide bodies, too dark to be seen with current surveys.
A new NASA mission will scan the entire sky with an infrared telescope - like a powerful set of night vision goggles to search for cool, or failed, stars, called brown dwarfs, and also dark comets and cometary fragments, of the type proposed by Professor Wickramasinghe and his team, that pose a previously unrecognised threat to our planet.
Comment: Hmmm. Is someone trying to tell us something?
If it might take decades or centuries of warnings, then perhaps it is already too late? Or perhaps some people have known and the events that we see transpiring on the Earth today are their "preparations"? Save the elite and let the rest of us die miserably, either from the hit or from the years of after effects?
No. Our leaders wouldn't do that
|Fireball in the Sky|
|WVPI Philadelphia |
October 28, 2004
An Action News viewer captured a fireball in the sky.
Brooks Efaw of Hamilton, New Jersey was videotaping his son's birthday party when he saw it on Saturday afternoon.
Other viewers have contacted us since we first showed the tape on Action News at five to say they saw it too. So what was it?
The FAA and the National Weather Service say they have no activity on record.
NASA says the fireball was probabl y space junk re-entering the earth's atmosphere.
|Confirmed: meteor passes over region|
|Friday, 29 October 2004|
|WAS it a bird, was it a plane ... no it was a meteor. |
Rumours have been flying thick and fast since a bright light with a short flame and trail of white behind it crossed over the Murraylands at 10.25am on Friday.
Listeners t o the local radio station were lead to believe a meteorite landed on in a field of cows on a property just outside Mannum. The rumours then escalated over the weekend with no-one just too sure of exactly what happened.
But it can be confirmed a meteor did cross over the Murraylands on Friday, but it did not land.
Astronomical Society of South Australia technical information officer Tony Beresford said a meteor had been seen in areas from Renmark to Adelaide before fading out.
The meteor was brighter than the full moon and left a trail of dust which took about 10 minutes to dissipate.
A sonic boom, which occurs when the meteor enters the atmosphere below 30 kilometres, was heard at Renmark and Gumeracha.
Mr Beresford has called on people in the Murray Bridge area to contact him if they heard the sonic boom, however he doubted it would have been noticed over the general traffic noise in the city centre without being mistaken for a car backfiring.
"I would be interested to see the footprint ... so anyone in the immediate vicinity of Murray Bridge who heard the boom I would appreciate hearing from them," he said.
The meteor travelled north-west across the State before breaking up.
|Sunspots more active than for 8000 years|
|Maggie McKee |
18:00 27 October 04
NewScientist.com news service
|The Sun has been more active in the last 70 years than it has for the previous 8000, according to an analysis of tree rings dating back 11,400 years. But researchers say its recent bout of hyperactivity does not account for the rapidly rising temperatures recorded on Earth over the last three decades. |
Sunspots are surface concentrations of the star's magnetic field and the more there are, the more energy the Sun is emitting. The dark features have been observed and recorded regularly since 1610.
Scientists have tried to reconstruct previous sunspot activity using ice cores and tree rings. These contain isotopes, such as carbon-14 and beryllium-10, created when high-energy particles from deep space, called cosmic rays, slam into the atmosphere. Fewer cosmic rays reach the Earth when the Sun is very active, because the charged particles from the Sun deflect them.
Now, a team led by Sami Solanki of the Max-Planck-Institut fur Sonnensystemforschung in Katlenburg-Lindau, Germany, has analysed records of trees preserved in riverbeds and bogs that date back 11,400 years to produce the most precise study yet of sunspot history.
Back in time
The team started by using sunspot records to calibrate models of how carbon-14 in tree rings correlate withsolar activity. The models "reproduce the observed record of sunspots extremely well, from almost no sunspots during the seventeenth century to the current high levels", writes Paula Reimer, a paleoclimate exp ert at Queen's University, Belfast, UK, in an article a ccompanying the research paper in Nature.
They then extrapolated the tree ring data backwards in time and discovered that no period in the last 8000 years has been as active as the last 70. About 75 sunspots have appeared every year in this period, compared to an annual average of about 30 over the last 11,400 years.
"We are living in extraordinary times as far as solar activity is concerned," says study co-author Manfred Schussler. "Extended periods of high activity seem to be much more rare than we previously thought."
Indeed, the data also showed that high activity periods only occurred for about 10% of the period studied, and tended to last for about three decades. "That's one of the interesting things - this latest cycle has already lasted longer than most do," says Reimer.
Inside the Sun
Models of the Sun can account for the well-known 11-year-long cycle of solar activity but the underlying reason for the 70-year high is unknown. "There is a consensus that the magnetic field underlying the solar activity is generated in the solar interior, but the details of this mechanism are still not understood," Schussler told New Scientist.
Furthermore, previous data from carbon-14 studies of tree rings suggest patterns change on scales of 200 years. "It seems like that periodicity should be driven by the Sun, but people argue back and forth on this all the time," Reimer told says. That is because the total energy emitted by the Sun actually changes by a relatively small amount as the nu mber of sunspots varies.
The new research will allow scientists to see if past climate changes "are too large to be explained by the sunspot cycle alone", Reimer says.
She notes that the current upsurge in sunspots is not enough to account for the approximate 0.5°C rise from pre-industrial temperatures over the last 30 years.
Journal reference: Nature (vol 431, p 1047, p 1084)
|Comment: We have a hypothesis to explain the Maunder Minimum, the seventy year period of a solar minimum mentioned in this article. We discuss it here.|
|Astronomers chart asteroid threat|
Thursday, 28 October, 2004
The team will be tracking asteroids with high-performance telescopes
The team from Queen's University in Belfast is monitoring asteroids in space to see if they are on a collision course with our planet.
Their crucial data will be fed into an international programme for protecting the Earth from any future impact.
On average 30 to 40 Near-Earth Objects (NEOs) - asteroids or comets on a path to Earth - are discovered each month.
More than 3,000 NEOs have now been found so far.
Now a team of astronomers at Queen's will be tracking these objects each week using large high-performance telescopes.
The UK Astrometry and Photometry Programme (UKAPP) for Near-Earth Objects, based at the university, is using the Faulkes Telescope North, which is physically located on the Hawaiian island of Maui.
At the end of this year they will also start using the twin Faulkes Telescope South at Siding Spring, Australia.
The telescop es' mirror size of 2m allows astronomers to see fainter NEOs.
We are looking at a series of asteroids two or three times a week now with these telescopes in Hawaii and Australia.
"In fact, we know that an asteroid will hit us at some point in the future.
"Of course, these things are out there and they just randomly hit us when the Earth gets in the way.
"However, generally it is not a 24-hour or even a 45-minute warning that we get. It is normally timescales of years or even decades."
Dr Fitzsimmons said that his project was acting as an "early, early wa rning system for the Earth".
He said that these long lead times gave scientists at the European Space Agency time to develop a strategy for dealing with an asteroid on a collision course.
Any object smaller than 50 metres across will not usually make it through the Earth's atmosphere intact so Dr Fitzsimmons is training his telescope on asteroids which are 50 to 100 metres across or larger.
"We are looking at a series of asteroids two or three times a week now with these telescopes in Hawaii and Australia," he said.
"There are 30 or 40 new objects discovered every month that we want to keep an eye on.
"So we only concentrate on the ones that do pass particularly close to us or are predicted to pass close in the next century or so."
|Experts try to solve meteorite mystery|
|Express News Service|
Vadodara, October 31: Forensic experts and geologists in village Nandgaon, about 18 kms from the nearest police station in Kaprada, South Gujarat, are trying to ascertain whether a black stone weighing a kg which fell in one of the farms, is a meteorite.
Villages like Nandgaon and Dharampur and other neighbouring villages in the hilly areas near the Maharashtra-Gujarat border have been experiencing unseasonal rains for past couple of days. However, on Saturday evening, the villagers reported hearing a loud bang-like noise and a streak of fire across the sky. The villagers first thought it was an aeroplane or a fireball, but it turned out to be a black stone which had fallen in a farm in the village, said a Kaprada police station personnel.
With rumours rife that the incident had led to burning of trees and could be a likely meteor, Kaprada pol ice personnel reached the spot and brought the stone to t he police station. It must be some stone boulder which might have fallen down due to the rains. There are no burnt trees or anything of sort in the area, said Abhaysinh Chudasama, Valsad DSP, who also visited the village.
Taking no chances, Chudasama added that a geologist from Valsad district collectorate had been summoned to check the stone.