|Meteor light show peaks on Thursday|
|Created: 03/05/05 |
By Rosemary Desmond
One of the most spectacular meteor displays of the year is on show this week for those up early enough to see it.
Up to 50 meteors an hour will charge into the Earth's atmosphere as it passes through the eta Aquarids, the trail of gravel and ice left in the wake of Halley's Comet, said Vince Ford at the Mount Stromlo Observatory near Canberra.
Activity this year will peak in the north-eastern sky a couple of hours before dawn on Thursday morning before the meteors taper off, Mr Ford said.
"Usually these travel fairly fast and because these are in the morning, we are meeting them head-on," he said.
"Sometimes you get yellows and greens, rather than just the normal orange streak, depending on the sort of gravel you run into and if it's mostly ice or a little bit of gravel mixed in."
Halley's Comet has swept through the inner solar system every 76 years and every autumn, the Earth travels through the comet's trail of particles up to the size of a small pea.
These slam into the earth's atmosphere at such speed they heat it until glowed, creating a meteor shower visible without a telescope.
Mr Ford said not all meteor showers were visible from the southern hemisphere but Australians would be able to get a good view of the eta Aquarids.
"It's worth getting up to have a look at," he said.
The next major meteor show will be the Perseids in August.
Science Editor, BBC News website
Astronomers have discovered 12 new moons orbiting Saturn, bringing its number of natural satellites to 46.
The moons are small, irregular bodies - probably only about 3-7km in size - that are far from Saturn and take about two years to complete one orbit.
All but one circles Saturn in the opposite direction to its larger moons - a characteristic of captured bodies.
Jupiter is the planet with the most moons, 63 at the last count. Saturn now has 46. Uranus has 27 and Neptune 13.
The latest ones were found last year using the Subaru telescope in Hawaii. Confirmation observations were made last month using the Gemini North telescope also situated in Hawaii.
Dave Jewitt of the University of Hawaii, co-discoverer of the objects, told the BBC News website that they were found as part of a detailed survey of the outer planets in order to better understand their origin.
The newly-found satellites were probably formed in the main asteroid belt between Mars and Jupiter, and scattered out of it by the tug of Jupiter's gravity.
"The key question is how they became captured by Saturn. The current models devised to explain how such bodies are captured are unable to explain why they reach the orbits they do," said Dr Jewitt.
"The new discoveries should improve our knowledge of satellite systems in general and should, eventually, lead to an understanding of how such small, irregular bodies are captured by the gravity of giant planets".
"Having more satellites to study will give us more data to plug into our computer simulations that may tell us what happened", he added.
Astronomers have found that all four giant planets - Jupiter, Saturn, Uranus and Neptune - possess about the same number of small irregular satellites irrespective of the mass of the planet, the orbit of the satellites, or if they were captured or formed in orbit. This observation remains unexplained.
Comment: Gee, the current models don't work. How sad is that! We have a hypothesis for Dr Jewitt. Imagine that the sun has a dark twin with a 27 million year orbit. When it comes closest to our sun, it crashes through the Oort cloud like a bowling bowl skattering the pins in all directions. These pieces of rock then are sent careening out of the Oort cloud into the solar system. As they come through, some of them are picked up by the gravitational pull of the largest planets and brought into orbit as new satellites.
They don't have to come from the asteroid band between Mars and Jupiter and so the current model doesn't need to explain how they manage to slip by Jupiter to get caught up by Saturn.
Saturn's pock-marked moon Phoebe could be a comet that was captured by the gravity of the ringed planet.
Data from the Cassini spacecraft suggests it originated in the frozen outer Solar System region called the Kuiper Belt - a reservoir for comets.
Two studies of Phoebe are carried in this week's issue of Nature magazine.
The tiny satellite is very different in its chemical composition to Saturn's larger moons and circles the planet in the opposite direction to them.
"It could have been a comet," said co-author Ralf Jaumann of the German Aerospace Center (DLR).
"Phoebe has a long journey behind it. It comes from the outer Solar System and probably rounded the Sun a few times before it was captured by Saturn's orbit. But we really don't know."
Phoebe and the objects that populate the Kuiper Belt are remnants of primordial objects that served as the building blocks of planets in our Solar System.
The saturnian satellite could itself be between 4 and 4.4 billion years old.
During the formation of the planets, gravitational interactions ejected some so-called icy planetesimals like Phoebe into distant orbits to join a native population of similar cosmic bodies.
This process formed the region we know today as the Kuiper Belt.
Phoebe itself must have migrated inwards and was captured by Saturn's gravity after the ringed planet formed from its planetary nebula.
Analysis of Phoebe's surface shows that it is one of the most complex Solar System objects yet studied.
Scientists have identified water-ice, possible clays, iron-bearing minerals and organics such as aromatic compounds, alkanes and nitriles on the 220km-wide Saturnian satellite. More complex organics also seem to be there, but scientists are yet to characterise them.
The observations come from Cassini's Visual and Infrared Mapping Spectrometer (Vims).
Dr Jaumann thinks clays could have formed through heating if Phoebe came close to the Sun before being captured by Saturn, forcing water ice to react with silicates.
"When we finally understand Phoebe, we will also understand the Kuiper Belt objects," Dr Jaumann explained.
Phoebe's surface composition also suggests that chemical activity in the first half billion years of the Solar System may have been more complex than previously thought.
"However, we have only seen the surface and this has probably undergone some alteration. But Phoebe has probably not had much alteration through high pressure or heating," Dr Jaumann added.
Cassini collected data on the moon during a close flyby on 11 June 2004.
By PATRICK ROWAN
On Sunday, April 24, people from Maine to Long Island reported everything from UFOs to missiles in the sky around 7:45 in the evening. Having ruled out a plane crash, a Federal Aviation Administration spokeswoman fingered the Lyrid meteor shower - a typically weak annual display that peaked days earlier - as the likely culprit. She said the "shower sparked a flurry of frantic phone calls to police departments across New England."
Accounts of an object's color, direction, or time, can be inconsistent, and leave the impression that multiple objects have appeared. But like others familiar with such sightings, I knew the reports likely originated from a single event. Witnesses calling the National Weather Service in Taunton, and the personnel who field those calls, tend to be more experienced skywatchers; thus their early conclusion that this was one fireball high in the atmosphere visible over wide areas.
The object appeared too early in the evening, and traveled in the wrong direction, to be a Lyrid. Not associated with any known shower, this was by definition a "sporadic" meteor - possibly a small asteroid 5 or 10 feet across. To my knowledge, if any fragments survived the plunge to earth, none have been found. Fragments from other falls can be seen at the Springfield Science Museum's "Rocks from Space" permanent exhibit.
What is certain is that this was one dazzling sight. "It was such a weird thing," said Elizabeth Duquette of Longmeadow, who spotted the fireball through her car windshield as she drove south along Main Street in Wilbraham. "The sky was still perfectly light," she said. "The ball was very distinct, and bright, bright green, and had a long bright white tail." Her view - limited by roadside trees - lasted only a few seconds. "If I had looked down to change my radio, I might have missed it," she said.
Bright fireballs actually occur quite often, but most go unnoticed in the daylight, late at night, or over uninhabited ocean. Fireballs that get news coverage tend to happen when people are out and about, which leads to more witnesses. One widely reported fireball over Spain this year appeared on Jan. 29, a Saturday night, at 10:30 p.m. Another passed over the northwestern U.S. at 7:40 p.m. on Saturday, March 12.
While talking about the April 24 event with Richard Sanderson, curator of physical science at the Springfield Science Museum, we realized that the great fireball of April 25, 1966, occurred 39 years ago almost to the day from last week's event. Seen by thousands from Washington, D.C., to eastern Canada, it was the most widely observed and photographed fireball of its time.
Sanderson noted that the museum had possession of a famous 16 mm film of the 1966 event shot from the Municipal Group in downtown Springfield by Channel 22 news photographer George Gambino (see photo).
How lucky I feel to have witnessed that incredible event. I was 13 years old and playing with a neighbor near my home in Florence just after sunset when I noticed a star in the southwest - strange since it was still almost daylight. Barely had that registered when a thin white line shot out of the "star's" left side. The "star" rapidly brightened and grew, and in an instant I realized it was the "star" moving, not that white line.
Yelling to my friend, we both watched it intensify into a flaming ball the size of a full moon that lumbered sluggishly across the western sky. The head became a hellish churning mass of blazing red eruptions, its teardrop shape leaving a swirling vortex of flame and smoke in its wake. Flaring brightly several times, this qualified as an exploding meteor, or bolide.
The detail visible through the clear air gave the impression this thing was low and close as fragments dropped away leaving their own smoke trails. Excited and terrified, who knows what we nervously shouted to each other. Never would we have guessed that it was 60 miles up and 100 miles away. Skimming the treetops to the northwest, it was disintegrating as it finally disappeared below the ridge line - at least 100 degrees from where it all began.
We hightailed it to alert family, neighbors and everyone else we could. The smoke train lingered for 20 minutes, long enough to share with others. Tuning in to WHMP, our local AM radio station, we were surprised to hear the announcer describe the smoke train from his studio's window in downtown Northampton.
Near the Campanile in Springfield, WWLP-TV news cameraman George Gambino managed to record much of the 31 second-long event on black and white 16 mm film. Frames from his movie soon graced the pages of Life Magazine's May 6 issue, and Sky & Telescope's June 1966 edition.
Outgassing lava flows: did they cause heat-induced reproductive failure in cold-blooded dinosaurs?
At least 50 percent of the world's species, including the dinosaurs, perished 65 million years ago. A large meteorite struck Mexico's Yucatan Peninsula around the same time, and most scientists blame this impact for the mass extinction.
Yet there is nothing that directly links meteorite impacts with the extinction of entire species. Scientists can recite a long list of the devastating environmental consequences of a large meteorite impact, but they cannot prove these effects have led to the simultaneous loss of life around the globe. Answering the question of how and why such a large variety of species died out at the same time is one of the greatest mysteries in paleontology.
While the exact reason for the Cretaceous-Tertiary (K-T) mass extinction is still under debate, other past extinctions have been clearly linked with climate change. As species become increasingly specialized to their environment, a substantial or sudden change will tend to threaten their survival. The Earth has gone through many cycles of extreme warming and cooling in its history, with an associated rise and fall of species.
Could such climate change have played a role in the K-T extinction? One proponent of this theory is Dewey McLean, a geologist at Virginia Polytechnic University who first published the idea in the 1970s. McLean thinks the Chicxulub impact in Mexico just added more stress to an environment that was already upset by the release of copious amounts of volcanic gases.
His culprit for the outgassing is the Deccan Traps, an ancient lava flow in west central India. This flood basalt volcanism, says McLean, upset the Earth's carbon cycle and led to long-term global warming. McLean suspects the dinosaurs gradually became extinct through heat-induced reproductive failure. He says that the higher temperatures, along with pH changes in ocean water, led to the extinctions seen in marine life at the time.
But Simon Kelley, a geologist at Open University in England, disagrees that the volcanic gas from the Deccan Traps could have caused such warming. He says the traps could have released, at most, only 2 percent of the carbon dioxide (CO2) already in the atmosphere -- not enough to trigger global warming. In addition, he notes that volcanoes release sulfur dioxide (SO2), which causes cooling rather than heating.
"The most recent example of massive volcanism, the Laki eruption of 1783-4 in Iceland, caused cooling in Europe and the northern USA, not heating," says Kelley. "The bitter winter in Paris was documented by Benjamin Franklin, envoy from the newly formed United States of America. Although SO2 is washed out rapidly, the signal of volcanism should be a combination of the both cooling and heating."
Kevin Pope, a geologist with Geo Eco Arc Research, says there is no evidence for global warming following the K-T extinction. "In fact, the best records show an abrupt cooling in the earliest Tertiary," says Pope.
Although McLean says that oxygen isotopes in ancient rocks indicate the Earth endured long-term global warming from the Cretaceous through the Tertiary eras, he admits the climate signal is mixed overall, with some rocks indicating cooling instead of warming. "We have much work to do in straightening out the K-T climate record," McLean says.
Dinosaurs first appeared and flourished during the Mesozoic, a generally warm era that lasted from 248 to 65 million years ago. Geologists split that large chunk of time into the Triassic, Jurassic and Cretaceous periods.
In the Triassic, all the continents were joined together in one huge landmass called Pangea. Such large swaths of land tend to influence their own climate, resulting in very dry conditions, with greater seasonal fluctuations than in coastal areas. Deserts spread across the continent during the Triassic, but there were still oases of tropical and temperate forests.
The jigsaw of continents that combined in the supercontinent, Gondwanaland. Continental drift and plate tectonics spread the land masses across the globe.
In the Jurassic, the great continent Pangea broke in half, creating Laurasia in the north and Gondwanaland in the south. Rainfall increased, ocean levels rose, and lush rain forests began to displace the deserts. These tropical forests eventually blanketed much of two continents.
By the end of the Cretaceous, the two continents had separated into even smaller landmasses that were well on their way toward their present continental shapes. The late Cretaceous experienced extreme climate fluctuations, where temperatures would drop and then rebound. This stressed the environment and likely resulted in the extinction of many species.
Not only did the breakup of large continents into smaller chunks of land alter the global climate, but all that tectonic movement also must have affected the ocean cycles that help regulate climate. The El Ni?o and La Ni?a ocean cycles of our own time are testament to how strong this marine influence can be.
After the extinction of the dinosaurs and 50 percent of the world's species, the early Tertiary (or Paleocene) era begins. Temperatures continued to fluctuate during this time period, although they were generally cooler than the end of the Mesozoic.
This cooling may have been due in part to the gasses and debris that was thrown into the atmosphere by the Chicxulub meteorite impact. But the continental shuffling in the late Mesozoic also suggests a great deal of volcanic activity must have been occurring at the time, throwing out gases that could have changed the balance of atmospheric gases.
The greatest accumulation of lava on the Earth's surface at the time was in the Deccan Traps of India. The Deccan lava first appeared millions of years before the K-T extinctions. Sankar Chatterjee, a paleontologist at Texas Tech University in Lubbock, Texas, says the fossil evidence shows that dinosaurs lived quite happily right near these lava flows.
"There are layers of sediment, lava, sediment, lava, and so on, indicating the lava stopped and then started again over a long period of time," says Chatterjee. "We find dinosaur eggs and bones throughout these layers, right up to the K-T layer. So they lived around the Deccan Traps while this lava was erupting."
But then, right about 65 million years ago, the intermittent trickle of lava became a vast flood. Geologists estimate that 90 percent of the lava in the Traps was released at that time.
The K-T extinction is not the first mass extinction event to coincide with a large outpouring of lava. An extensive lava flow in Siberia occurred about 250 million years ago, around the same time as the Permian-Triassic (P-Tr) extinction event, the largest extinction of life in Earth's history.
The P-Tr extinction is often referred to as the "Great Dying," because 90 percent of marine and 70 percent of land species perished.
In 2004, a group of scientists announced that the Bedout crater, buried off the northwestern coast of Australia, is about 250 million years old, and therefore may coincide with the P-Tr extinction. The scientists say the Bedout crater was created by a meteorite similar to the one that made the Chicxulub crater in Mexico's Yucatan Peninsula.
If Bedout does prove to be an impact crater, it would point to another instance where both a giant meteorite impact and massive flood basalt volcanism occurred around the same time as a mass extinction.
Yet the evidence indicating Bedout is an impact crater is not as firmly established as the impact evidence for Chicxulub, and some scientists say there is little proof Bedout is anything but a volcanic structure.
Peter Ward, a geologist with the University of Washington in Seattle, doesn't think the P-Tr extinction was caused by impact. He recently published a paper in the journal Science that blames global warming on the Permian extinction. Just as McLean thinks the Deccan Traps led to the K-T extinctions, Ward thinks the Siberian lava flows could have eventually led to the P-Tr mass extinction.
Ward says that the extinction rate in the P-Tr was much more gradual than the K-T, occurring almost imperceptibly over millions of years. Yet McLean believes the K-T extinction rate also was slow and incremental.
"I use the term K-T transition' because the biological turnover actually began during the Late Cretaceous, and extended into the Early Tertiary," says McLean. "As indicated by the geobiological record, there was no global catastrophic extinction of most of Earth's life at the K-T boundary 65 million years ago."
Most paleontologists disagree, however. The consensus is that the K-T extinctions took place over a relatively brief point in time.
"The best paleontological data bases, like marine foraminifera and dinoflagellates and terrestrial pollen, all point to an abrupt catastrophic event at the K-T boundary," says Pope.
These microscopic fossils are preferable to dinosaur bones when it comes to determining the time scale of the K-T extinction, says Pope, because dinosaur fossils are so rare that they can not reliably indicate whether an extinction was sudden or gradual. (A "short" period or "sudden" event in the fossil record can describe something that occurred over hundreds or thousands of years, due to the margin of error in the dating methods.)
Looking at the bone record we do have, it's clear that many dinosaur species died out as a part of the natural extinction cycle long before the Chicxulub meteorite hit the Earth, and other species were in decline. But species that seemed to have robust populations before the impact suddenly disappear as the fossil record enters the Tertiary.
In fact, the fossil record indicates that dinosaurs achieved their greatest species variety only a few million years before they became extinct. This suggests that something dramatic must have occurred to cause such a definitive end to the reign of the dinosaurs.
Most scientists who study the K-T believe the Chicxulub impact alone caused the extinction, because the preponderance of evidence suggests the two events are closely linked in time. But, says Kelley, "we still have a lot to learn." He notes that, historically, "there is a better correlation between volcanism and mass extinctions than impact and mass extinction."
Even if the K-T was triggered by atmospheric changes due to massive volcanic outgassing, that does not answer many other questions about the extinction event. For instance, while the dinosaurs and many other species perished 65 million years ago, a variety of other animals survived, including the rodent-like mammals that eventually became human beings. If the environment became so hostile that half of all life on Earth died, then how did animals like birds, frogs, crocodiles, and mammals live on?
Comment: What if all of these factors are related, and are, in fact, part of a larger series of events? Lost in the arguing back and forth is the undeniable fact that from time to time, something disastrous happens to our world, and it leads to the mass extinction of many species on the planet.
Our hypothesis is that our sun has a companion star whose orbit brings it to its closest point with our sun every 27 million years, triggering other events that lead to these catastrophes and extinctions on earth. It is probable that as the dark sun passes through the Oort cloud, it knocks out large numbers of asteroids and sends them careening into the solar system. The last ten years have seen a rather surprising increase in the number of "moons" of the outer planets. Scientists suggest that they were always there and it is only our better telescopes that permit us to find them.
Another possible explanation is that these new "moons" were captured by the gravity of the larger, outer planets as they came whizing by on their way in from the Oort cloud. Our hypothesis has the unfortunate corallary of supposing that there may well be numerous other rocks that were not caught and that are continuing there way towards the inner solar system, perhaps even towards our home.
The gravitational effects of the dark star companion are not known. Perhaps it could provoke such pressure on our planet that internal acitivty would increase leading to more earthquakes and volcanic activity. A collision with a meteorite or comet might also unleash a period of geological upheaval as the earth recovered from the blow.
In act, what we know about how the earth operates and the forces at work both internally and from without far surpass that which we know. There is debate over whether the earth's core is solid or molten. A recent test suggests it is solid, but no one is certain.
The 17th century saw a 75-year solar minimum. During the period there were no solar maximums. Scientists are at a loss to explain why. Had our dark star companion be in the neighborhood during that period, it's gravitational effects may well have dampened the sun's activity causing the extended solar minimum and the rocks it knocked out of its way would have been travelling towards us for close to 350 years.
For more on this subject, see Laura Knight-Jadczyk's article Independence Day.
There's a myth about the sun. Teachers teach it. Astronomers repeat it. NASA mission planners are mindful of it.
Every 11 years solar activity surges. Sunspots pepper the sun; they explode; massive clouds of gas known as "CMEs" hurtle through the solar system. Earth gets hit with X-rays and protons and knots of magnetism. This is called solar maximum.
There's nothing mythical about "Solar Max." During the most recent episode in 2000 and 2001, sky watchers saw auroras as far south as Mexico and Florida; astronomers marveled at the huge sunspots; satellite operators and power companies struggled with outages.
Now the sun is approaching the opposite extreme of its activity cycle, solar minimum, due in 2006. We can relax because, around solar minimum, the sun is quiet. Right?
"That's the myth," says solar physicist David Hathaway of the NASA Marshall Space Flight Center. The truth is, solar activity never stops, "not even during solar minimum."
To show that this is so, Hathaway counted the number of X-class solar flares each month during the last three solar cycles, a period spanning 1970 to the present. X-flares are the most powerful kind of solar explosions; they're associated with bright auroras and intense radiation storms. "There was at least one X-flare during each of the last three solar minima," says Hathaway.
This means astronauts traveling through the solar system, far from the protection of Earth's atmosphere and magnetic field, can't drop their guard--ever.
Recent events bear this out: Rewind to January 10, 2005. It's four years since solar maximum and the sun is almost blank--only two tiny sunspots are visible from Earth. The sun is quiet.
The next day, with stunning rapidity, everything changes. On January 11th, a new 'spot appears. At first no more than a speck, it quickly blossoms into a giant almost as big as the planet Jupiter. "It happened so quickly," recalls Hathaway. "People were asking me if they should be alarmed."
Between January 15th and 20th, the sunspot unleashed two X-class solar flares, sparked auroras as far south as Arizona in the United States, and peppered the Moon with high-energy protons. Lunar astronauts caught outdoors, had there been any, would've likely gotten sick.
So much for the quiet sun.
It almost happened again last month. On April 25, 2005, small sunspot emerged and--d?j? vu--it grew many times wider than Earth in only 48 hours. This time, however, there were no eruptions.
Why not? No one knows.
Sunspots are devilishly unpredictable. They're made of magnetic fields poking up through the surface of the sun. Electrical currents deep inside our star drag these fields around, causing them to twist and tangle until they become unstable and explode. Solar flares and CMEs are by-products of the blast. The process is hard to forecast because the underlying currents are hidden from view. Sometimes sunspots explode, sometimes they don't. Weather forecasting on Earth was about this good ... 50 years ago.
Researchers like Hathaway study sunspots and their magnetic fields, hoping to improve the woeful situation. "We're making progress," he says.
Good thing. Predicting solar activity is more important than ever. Not only do we depend increasingly on sun-sensitive technologies like cell phones and GPS, but also NASA plans to send people back to the Moon and then on to Mars. Astronauts will be "out there" during solar maximum, solar minimum and all times in between.
Will the sun be quiet when it's supposed to be? Don't count on it.
Comment: We would be interested in what a longer period would disclose. Are the last three solar minimums representative of the sun's activity over the last three centuries?
A new study finds whale beachings coincide with changes in solar activity. (Mavis Burgess)
Surges of solar activity may cause whales to run aground, possibly by disrupting the creatures' internal compasses, according to German scientists.
University of Kiel researchers Klaus Vaneslow and Klaus Ricklefs looked at sightings of sperm whales found beached in the North Sea between 1712 and 2003.
They compared the record with another set of historical data - astronomers' observations of sunspots, an indicator of solar radiation.
They found that more whale strandings occurred when the sun's activity was high.
The sun experiences cycles of activity which range from eight to 17 years, with 11 years being the average.
Short cycles are linked with periods of high energy output, while long cycles are believed to be low energy.
Changes in levels of solar radiation have a big effect on earth's magnetic field.
The most notable events are solar flares that cause shimmering lights, called aurorae, in the magnetic fields in polar regions.
Big solar flares can also disrupt telecommunications and power lines and knock out delicate electronic circuitry on satellites.
The researchers found that of the 97 stranding events reported around the coastal countries of the North Sea over the 291 years, 90 per cent occurred when the sun cycles were below average in duration. [...]
Helsinki - An exceptionally bright "fireball" was spotted late on Tuesday slicing through the sky over Finland before exploding over the country's border with Russia, the Finnish Astronomical Association (URSA) said on Wednesday.
The phenomenon was witnessed by dozens of people in the eastern part of the country.
"Our mathematicians have roughly calculated that the (fireball) began its decent over our eastern border and ended in an explosion over the Russian Karelia region," URSA newsletter editor Marko Pekkola said.
Closer calculations will be needed to determine the exact route taken by the "fireball", which was probably an incandescent meteorite, Pekkola added.
|Marshes Tell Story Of Medieval Drought, Little Ice Age, And European Settlers Near NYC|
Aside from views of cattails and blackbirds, the marshes in the lower Hudson Valley near New York City offer an amazingly detailed history of the area's climate. Sediment layers from a tidal marsh in the Hudson River Estuary have preserved pollen from plants, seeds, and other materials. These past remnants allowed researchers from Columbia University, New York, N.Y. and NASA to see evidence of a 500 year drought from 800 A.D. to 1300 A.D., the passing of the Little Ice Age and the impacts of European settlers.
Plants provide an indicator of climate because the well-being of a species is controlled by the temperature and moisture of a region, and whether those conditions suit a type of plant. That's why if you draw latitudinal or horizontal lines around the world you'll find very similar species growing along those lines, like tropical plants around the equator, or tundra and northern or boreal forest species in a circumference south of the North Pole.
From the pollen record found in sediments in Piermont Marsh of the lower Hudson Valley, a Medieval Warm period was evident from 800 to 1300 A.D. Researchers know this from the striking increases in both charcoal, a sign of dry vegetation and fires, and pollen from pine and hickory trees. Prior to this warming spell, there were more oaks, which prefer a wetter climate. [...]
During this drought period, a core drilled into the marsh bed showed large influxes of inorganic soil particles, a sign of erosion. Plant roots hold soil in place, but with drought and plant deaths, more erosion occurs.
Droughts like this also make the bay saltier, and evidence of this was found by an increase in salty marsh plants, like saltmarsh cordgrass. The changing salinity of the marshes and estuaries could present future water quality issues in the event of a drought. For example, heading north up the Hudson River, the city of Poughkeepsie draws its municipal water directly from the river. Because the salinity of the river changes with drought, causing saltier water to move further north, salinity changes have the potential to affect the water supply of the city.
During the Little Ice Age from the early 1400s to late 1800s, the vegetation changed again to plants that favored cooler and wetter climates. The core records revealed increases in spruce and hemlock that prefer cooler and wetter climates.
Similarly, when Europeans settled the area they cleared the forests for agriculture. The pollen record reflects this with a vast decline in tree pollen and an increase in pollen from weedy plants like ragweed, plantain, sorrel and dock. Inorganic soil particles also went up following European settlement.
Peteet points out that researchers could use these methods to similarly learn about climate in other parts of the world.
Comment: While the article above shows evidence of a "Little Ice Age" from the early 1400s to late 1800s, it does not go into any detail as to why this ice age may have occurred. Laura Knight Jadczyk's research, explicated in her book The Secret History of the World suggests that the period know as "the dark ages" may have been caused by the occurrence of cyclical cometary showers that regularly bombard the earth.
One reasonable theory postulates that impacts of such celestial objects onto the surface of the planet would raise enormous amounts of dust into the air, thus blocking out the sun's rays for many years causing a significant decrease in overall global temperature, or "little ice age".
What the government seems well aware and scientists aren't saying is that the recent appearance of many similar meteor sightings all over the world could be the beginning of another such cycle in present times which will make the so-called "dark ages" seem like a stroll through Disneyland.
|Astronaut Asks Congress to Investigate Threatening Asteroid|
| By Leonard David |
Senior Space Writer
posted: 19 May 2005
WASHINGTON, D.C. ñ A former NASA astronaut will call on the U.S. Congress to evaluate an asteroid with a small chance of hitting Earth in 2036 and suggest lawmakers consider a space mission to monitor the object, SPACE.com has learned.
Russell Schweickart arrives here today to make his case. He'll also ask Congress to assign to a government agency the responsibility of protecting the public from space rocks.
The call to action stems from an orbiting hunk of stone that for a few days around Christmas had scientists on the edges of their seats.
The asteroid, named 2004 MN4, was found last year. It orbits the Sun but crosses the path of Earth. In December, preliminary observations showed it might strike in 2029, according to NASA scientists. It briefly had the highest odds ever assigned to a possible collision. Further investigation ruled out the 2029 impact scenario, but scientists cannot yet rule out an impact in 2036.
The odds of a collision in 2036 are about 1-in-10,000, Schweickart says.
In fact, there are several scenarios between 2034 and 2065 in which 2004 MN4 has even smaller odds of striking. Schweickart and other scientists stress, however, that future observations are likely to reduce all these odds to zero.
Time to act
Meanwhile, Schweickart thinks the time to act is now.
SPACE.com was provided a copy of the paper Schweickart will present. In it, he carries out an informal analysis of the situation. He notes that the asteroid will be mostly out of view from 2006 to 2012. When it re-emerges, fresh observation will likely reduce the 2036 impact chance to zero, he said.
"However, there is a slim chance that we will not be able to draw this conclusion and that an impact will still be possible," he writes.
"One of the first things Iím calling for is validation and checking of the analysis Iíve gone through and the conclusions that fall out of my work," Schweickart told SPACE.com.
Schweickart heads up the B612 Foundation, which since 2003 has advocated for more research and action to protect Earth from stray asteroids.
Call to action
Should his analysis prove correct after formal study, Schweickart says serious consideration should be given to first placing a radio transponder on the asteroid in order to better track its whereabouts.
The former Apollo astronaut will take his message to Congressional lawmakers and detail his concerns at the International Space Development Conference being held here this week by the National Space Society, a space advocacy organization.
Astronomers agree that sooner or later Earth will be struck by a damaging asteroid. While one could sneak up on us any day, the overwhelming odds are that any potential significant impact will be known years in advance.
NASA has been charged by Congress with finding potentially hazardous space rocks. Yet only last year, after a separate brief scare, did officials formalize lines of communication between NASA's top brass and the astronomers who find and monitor space rocks.
Still, there are no formal lines of communication between NASA and the White House to handle an imminent threat. And there is no U.S. agency to which the issue of protection of the public and property from the impact of near-Earth asteroids is assigned, Schweickart points out. Who would decide on whether and how to deflect an incoming threat? What agencies would be mobilized to deal with an impact?
The U.S. Congress should take action and assign that responsibility, he said. [...]
Comment: Based on an accurate reading of the earth's history, it seems very likely that there are an enormous number of space rocks headed our way right now. So, if it's true that any kind of major impact will be known years in advance, then it seems some people in highly placed positions of power are well aware of this fact, and are working overtime to make sure this information does not reach the ears of the general public.
|Area man says meteorite hit his driveway|
| By Patricia Wolff |
of The Northwestern
Posted May 22, 2005
WAUTOMA, Wisconsin - When something that looked curiously like a meteorite landed in Bill Hicks's driveway and left a sizable indentation, he wondered out loud if maybe it was meant for his neighbor.
"We live near Camp Phillip. Maybe God was trying to speak to them and he missed," Hicks mused.
Pastor Tom Klusmeyer laughed out loud when he heard that."We've got some neighbors who wish we weren't here. Maybe he's one of them. We sing and make noise and praise God. Some of the neighbors want peace and quiet," Klusmeyer said.
Camp Phillip is a ministry of the Wisconsin Evangelical Lutheran Synod Church that caters year-round to children and families. Hicks lives about a mile from the camp on Buttercup Avenue west of Wautoma.
"I don't even hear them," Hicks said.
He definitely heard the rock that landed in his driveway about three weeks ago. It sounded like a big thunderclap so he didn't think much of it at the time.
"I got up in the morning and saw the hole and said, 'What the hell is that?'" Hicks said.
He filled the hole, which he estimated at about 2 feet deep, with cat litter, gravel and rocks so that his SUV wouldn't get snarled up when he tried to back out, he said.
Hicks and his roommate Larry Linde haven't shown the rock to any experts but they've asked someone from the astronomy department at the University of Wisconsin-Oshkosh to take a look at it.
"It definitely looks like pictures I've seen of meteorites," Linde said.
It measures about 4 inches by 6 inches and is reddish-brown in color.
Neither Hicks nor Linde would be surprised if the rock turned out to be a meteorite, they said. Other rare occurrences have happened on their property.
"We've been struck by lightning twice since I've been living here," Hicks said.
The same thing happened at the camp, Klusmeyer said.
But, a meteorite is more rare than that.
"You're four times more likely to get hit by lightning than a meteorite," Linde said.
|Meteor theory gets rocky ride from dinosaur expert|
| Rex Dalton |
Published online: 24 May 2005; | doi:10.1038/news050523-2
US palaeontologist amasses data against Mexican crater hypothesis.
The widely held theory that a particular meteorite strike on Mexico wiped out the dinosaurs is under sharp attack, again.
The asteroid that created the Chicxulub crater in the Yucat?n peninsula in Mexico arrived too early to have caused the Cretaceous-Tertiary mass extinction, according to evidence given on 23 May at an American Geophysical Union conference in New Orleans, Louisiana.
A team led by palaeontologist Gerta Keller of Princeton University, New Jersey, reported that a sediment core drilled in east Texas emphatically confirms a study that the group released two years ago. Sediments of glass sprayed out by the Chicxulub impact are separated from fossils killed during the mass extinction by a 300,000-year gap, they argue.
"I believe this is the mortal wound for the Chicxulub theory," says Keller. Scientists should mount a search for the crater left by the meteorite that was really responsible for the mass extinction, she adds.
However, some sedimentologists are being persuaded by the core specimens. Paul Wignall of the University of Leeds in Britain calls Keller's evidence "quite convincing", although he didn't attend the meeting.
Two years ago, Keller stunned a symposium at an American Geophysical Union meeting in Nice, France, with an analysis of a section of a 1,500-metre core drilled in the Yucat?n, only 60 kilometres from the Chicxulub crater.
The Yucat?n core, called Yaxcopoil-1, was the result of an international project designed to provide the most advanced record of events at the Cretaceous-Tertiary boundary. But it was beset by strife over access to the core and subsequent interpretations (see 'Hot Tempers, Hard Core').
Keller claimed the crater preceded mass extinction by 300,000 years1. Her critics say the sediment layers she sees are actually rubble from collapsing crater walls. But her team argues that palaeomagnetic dating and minute fossil analysis rules this out.
To settle the dispute, Keller drilled 2,000 kilometres north of the crater to get a sedimentary view unaffected by backwash.
The Brazos River Valley, Texas, is widely accepted as the best location to check Chicxulub impact debris from afar. In March, three 50-metre-deep holes were drilled near the small town of Rosebud to extract sediment from the time of the mass extinction.
From a 2-metre section of the best core, the Keller team charted what they say shows the 300,000-year gap. First, there is a 2 centimetre-thick layer of altered glass called bentonite that is the ejected material from the Chicxulub impact. About 50 centimetres above that lie sediments beds from the tsunami set off by the asteroid. Finally, a full 1.2 metres above these beds, there is the detritus of the mass extinction, represented by fossils of tiny plants and animals that died.
The National Science Foundation has given Keller US$40,000 to drill another core in autumn 2006. This one will be on the opposite side of the Chicxulub crater, some 7,800 kilometres south near the city of Recife in Brazil. Keller hopes to find evidence that will finally quiet her critics.
Comment: Interesting that the researcher found the interval was 300,000 years...To understand why, check out the series The Wave by Laura Knight-Jadczyk, or read the books, the much expanded Wave series in print.
|Fast and Furious Solar Storm Shocks Earth and its Scientists|
|By Robert Roy Britt |
Senior Science Writer
24 May 2005
Any astronomer will tell you that the Sun is unpredictable. But on Jan. 20, 2005 it was dangerously so, leaving scientists to rework theories of how space storms operate and showing that interplanetary space travel will be a deadly serious business.
In new studies presented today, researchers detailed a solar outburst that shocked Earth with the highest dose of radiation measured in five decades.
The tempest arrived frighteningly fast.
Other solar outbursts have provided more dramatic pictures, more threatening X-ray flares, and tremendous coronal mass ejections of hot gas that arrive several hours later. But the solar event at 2 a.m. ET on that January morning created an intense burst of energetic protons that, surprisingly, tripped radiation monitors all over the planet within moments.
"This flare produced the largest solar radiation signal on the ground in nearly 50 years," said Richard Mewaldt of the California Institute of Technology. "But we were really surprised when we saw how fast the particles reached their peak intensity and arrived at Earth."
Mewaldt is a co-investigator on NASA's Advanced Composition Explorer (ACE) spacecraft, which monitored the event. Several studies on the flare are being presented this week at a meeting of the American Geophysical Union (AGU) New Orleans.
The raging proton storm peaked in 15 minutes. Normally, the most intense part of a proton event takes two hours or longer to build up.
"That's important because it's too fast to respond with much warning to astronauts or spacecraft that might be outside Earth's protective magnetosphere," Mewaldt said. "In addition to monitoring the Sun, we need to develop the ability to predict flares in advance if we are going to send humans to explore our solar system." [...]
Flares emanate from sunspot groups, regions of the Sun where intense magnetic energy caps upwelling solar material, creating cooler, darker spots. The surprising January flare came on the heels of a series of other very large but otherwise normal flares from the same sunspot group. Scientists can't say why the fifth event was so unusual."It means we really don't understand how the Sun works," Lin said.
Spot on Saturn's Titan Puzzles Experts
| May 28, 2005 |
From Times Staff and Wire Reports
Scientists are baffled by an unusual bright spot about the size of West Virginia on Saturn's big moon, Titan.
The Cassini spacecraft captured an image of the 300-mile blotch during a flyby of Titan this year.
"At first glance, I thought the feature looked strange, almost out of place," Robert Brown, a member of the Cassini project, said Wednesday.
Scientists believe the spot could have formed recently as a result of an asteroid impact, a landslide or a volcanic eruption. Another Titan flyby in July could determine what the spot is.
|Meteor shower sparks calls to police|
|07 June 2005|
A meteor shower was visible throughout New Zealand last night, prompting calls to police about distress flares.
Inspector Kristy Meates said 10 calls were logged between 7pm and 7.40pm in the central and lower North Island. More calls were reported elsewhere.
Callers claimed to have seen "greeny-blue flares", but distress flares are red. The reaction was similar to that on August 3 last year when people reported seeing fireballs. They were thought to have been from the Perseid meteor shower, associated with the comet Swift-Tuttle.
Carter Observatory's senior astronomer Brian Carter said meteor showers were uncommon in June but not unheard of. They were made up of space matter entering Earth's atmosphere.
Such events were spectacular to watch but held greater significance if people saw meteors landing on the ground - something which happened rarely.
|New solar storm shakes space weather theory|
January 2005 was a stormy month--in space. With little warning, a giant spot materialized on the sun and started exploding. Between January 15th and 19th, sunspot 720 produced four powerful solar flares. When it exploded a fifth time on January 20th, onlookers were not surprised.
They should have been. Researchers realize now that the January 20th blast was something special. It has shaken the foundations of space weather theory and, possibly, changed the way astronauts are going to operate when they return to the Moon.
Sunspot 720 unleashed a new kind of solar storm.
Scant minutes after the January 20th flare, a swarm of high-speed protons surrounded Earth and the Moon. Thirty minutes later, the most intense proton storm in decades was underway.
"We've been hit by strong proton storms before, but [never so quickly]," says solar physicist Robert Lin of UC Berkeley. "Proton storms normally develop hours or even days after a flare." This one began in minutes.
Proton storms cause all kinds of problems. They interfere with ham radio communications. They zap satellites, causing short circuits and computer reboots. Worst of all, they can penetrate the skin of space suits and make astronauts feel sick.
"An astronaut on the Moon, caught outdoors on January 20th, would have had almost no time to dash for shelter," says Lin. The storm came fast and "hard," with proton energies exceeding 100 million electron volts. These are the kind of high-energy particles that can do damage to human cells and tissue.
"The last time we saw a storm like this was in February 1956." The details of that event are uncertain, though, because it happened before the Space Age. "There were no satellites watching the sun."[...]
"CMEs can account for most proton storms," says Lin, but not the proton storm of January 20th. According to theory, CMEs can't push material to Earth quickly enough.
Back to the drawing board: If a CME didn't accelerate the protons, what did?
"We have an important clue," says Lin. When the explosion occurred, sunspot 720 was located at a special place on the sun: 60o west longitude. This means "the sunspot was magnetically connected to Earth."
He explains: The sun's magnetic field spirals out into the solar system like water from a lawn sprinkler. (Why? The sun spins like a lawn sprinkler does.) The magnetic field emerging from solar longitude 60o W bends around and intersects Earth. Protons are guided by magnetic force fields so, on January 20th, there was a superhighway for protons leading all the way from sunspot 720 to our planet. [...]
Geophysicist charts wave heights from Northwest to Baja
|David Perlman, Chronicle Science Editor|
Monday, June 13, 2005
If a giant magnitude 9 earthquake strikes someday along the coast of the Pacific Northwest, or if, against all odds, an errant asteroid plunges into the ocean many miles off California, a monstrous tsunami could drown low-lying lands all up and down the continent's western edge -- and now a UC Santa Cruz scientist has calculated the sweep of such an event.
Spurred by the tragedy of December's great Sumatra quake and the hundreds of thousands of deaths claimed by the waves that swept across the Indian Ocean, geophysicist Steven Ward has estimated the heights that a similar quake-spawned tsunami would reach, running up along the shores from British Columbia as far south as the tip of Baja California.
"We need to know what the tsunami dangers are along any coastal area," Ward says, "and as our instruments and technology and modeling techniques improve, so we can refine our ability to forecast what might happen."
Using knowledge gleaned from evidence of a magnitude 9 quake in the Cascadia subduction zone some 300 years ago, the behavior of last December's Sumatra quake, careful scrutiny of detailed ocean bottom data all along the Pacific Coast and what he calls "the laws of water physics," Ward has created a hazard map that shows what may happen should another major quake hit the same area in the future. The Cascadia zone is a region where the eastern edge of a great undersea slab of the Earth's crust, called the Juan de Fuca Plate, is continually diving beneath the west edge of the North American Plate and thrusting the continental side of the crust upward.
To model the event's effects, Ward assumes that in a huge quake on the Cascadia subduction zone, the two crustal plates would abruptly slip apart vertically by at least 50 feet in three successive blocks from south to north, generating a 9.2 magnitude quake. Aside from enormous quake damage on land for hundreds of miles, Ward estimates the resulting tsunami would pile a wave more than 20 feet high crashing onto the Oregon-Washington coast, inundating Seattle and the entire Puget Sound region as well as Portland and the mouth of the Columbia River.
Crescent City in California's Del Norte County -- where a smaller tsunami killed 11 people in 1964 after a magnitude 9 Alaska quake -- would see a wave of more than 11 feet, and the tsunami sweeping the coast at the Golden Gate and Monterey Bay would be more than 10 feet . At Santa Barbara, Ward calculates, the wave height would be 6.5 feet, and smaller waves would crash against the shore as far south as the tip of Baja California.
"These calculations are still rough," Ward concedes, "but they do indicate a level of danger that needs to be considered."
The evidence of the great temblor 300 years ago was discovered along the coast of Washington and Oregon by Brian Atwater, a U.S. Geological Survey scientist in Seattle. And Japanese scientists deciphering old tsunami records in their coastal towns calculated that the event had sent a major wave speeding across the Pacific in 10 hours to damage many coastal villages on Honshu, Japan's main island.
Another giant earthquake is nearly a certainty in the unstable coastal regions of Oregon and Washington, but many scientists are also considering the effect of an event that would have no precedent in recorded history -- and have concluded that an even greater tsunami might be generated if an asteroid were ever to plunge into the ocean off the West Coast.
Russell "Rusty" Schweickart, the Apollo 9 lunar module commander who is now a retired businessman in Tiburon, has created a foundation with the intention of persuading government agencies to plan for the possibility of an asteroid impact in the ocean -- admittedly, the astronaut says, no more than a 10,000-to-1 chance, but one that could wreak havoc on coastal communities. The specific asteroid that worries him most has been designated by NASA astronomers as 2004MN4, and it is expected to pass within 26,600 miles of Earth less than 25 years from now.
Scientists at NASA's Near Earth Object Program, which tracks the course of some 70 comets and asteroids that appear to be headed somewhere within thousands of miles of the Earth, calculate that 2004MN4 should make its closest approach to Earth on April 13, 2029, when it will be vividly in sight for everyone on Earth to watch. But a collision with Earth is impossible that year, they have reported -- and, they say, "no subsequent Earth encounters in the 21st century are of concern."
Schweickart, however, has concluded there is a remote possibility that the asteroid would collide with Earth in 2036. He and his foundation are urging Congress to send a spacecraft to the asteroid before 2014 to put a radio transponder on the object, which would define the asteroid's trajectory far more accurately than any other technique.
"While the probability of a highly destructive impact in the immediate future is slight," Schweickart says, "the consequence of such an occurrence is extreme, and mitigation efforts should begin now."
Schweickart enlisted Ward to determine what kind of tsunami might be created if the asteroid did crash in the Pacific in 2036.
And Ward's calculations indicate a tsunami from the crash would be far more devastating than anything known in history: Peak wave heights, he said, would reach 17 feet in southern Alaska, more than 55 feet all along the California coast, 15 feet in Hawaii, and 20 feet at Puerto Vallarta, the Pacific beach resort in Mexico.
Schweickart maintains that if the transponder were to indicate the object's course makes a collision more likely, there could then be time to conceive, plan, design and launch some kind of unspecified "deflection mission."
"Either way, our course of action is clear," he says. "We either plan another series of cocktail parties to watch the asteroid go by in 2036 -- as we will have done in 2029 -- or we mount the most important space mission in human history."
|Fireworks Likely When NASA Blows Up Comet|
|By ALICIA CHANG|
Jun 26, 5:14 PM (ET)
LOS ANGELES (AP) - Not all dazzling fireworks displays will be on Earth this Independence Day. NASA hopes to shoot off its own celestial sparks in an audacious mission that will blast a stadium-sized hole in a comet half the size of Manhattan. It would give astronomers their first peek at the inside of one of these heavenly bodies.
If all goes as planned, the Deep Impact spacecraft will release a wine barrel-sized probe on a suicide journey, hurtling toward the comet Tempel 1 - about 80 million miles away from Earth at the time of impact.
"It's a bullet trying to hit a second bullet with a third bullet in the right place at the right time," said Rick Grammier, project manager at NASA's Jet Propulsion Laboratory in Pasadena.
Scientists hope the July 4 collision will gouge a crater in the comet's surface large enough to reveal its pristine core and perhaps yield cosmic clues to the origin of the solar system.
NASA's fleet of space-based observatories - including the Hubble, Spitzer and Chandra telescopes - along with an army of ground-based telescopes around the world are expected to record the impact and resulting crater.
The big question is: What kind of fireworks can sky-gazers expect to see from Earth?
Scientists do not know yet. But if the probe hits the bull's-eye, the impact could temporarily light up the comet as much as 40 times brighter than normal, possibly making it visible to the naked eye in parts of the Western Hemisphere.
"We're getting closer by the minute," Andrew Dantzler, the director of NASA's solar system division, said earlier this month. "I'm looking forward to a great encounter on the Fourth of July."
If the $333 million mission is successful, Deep Impact will be the first spacecraft to touch the surface of a comet. In 2004, NASA's Stardust craft flew within 147 miles of Comet Wild 2 on its way back to Earth carrying interstellar dust samples.
Scientists say Deep Impact has real science value that will hopefully answer basic questions about the solar system's birth.
Comets - frozen balls of dirty ice, rocks and dust - are leftover building blocks of the solar system after a cloud of gas and dust condensed to form the sun and planets 4 1/2 billion years ago. As comets arc around the sun, their surfaces heat up so that only their frozen interiors possess original space material.
Very little is known about comets and even less is known about their primordial cores. What exactly will happen when Tempel 1 is hit on the Fourth of July is anybody's guess. Scientists believe that the impact will form a circular depression that will eject a cone-shaped plume of debris into space.
But not to worry. NASA guarantees that its experiment will not significantly change the comet's orbit nor will the smash-up put the comet or any remnants of it on a collision course with Earth.
Discovered in 1867, Tempel 1 is a short-period comet, meaning that it moves around the sun in an elliptical orbit between Mars and Jupiter and can be sighted every six or so years.
The Deep Impact spacecraft shares the same name as a 1998 Hollywood disaster movie about a comet headed straight for Earth. NASA says that the names for the space mission and blockbuster movie were arrived at independentl y around the same time and by pure coincidence.
The spacecraft blasted off from Cape Canaveral, Fla., in mid-January to make its six-month, 268 million-mile voyage. In March, scientists got a scare when test images from one of Deep Impact's telescopes were slightly out of focus. The problem was fixed, and a month later, Deep Impact took its first picture of Tempel 1 from 40 million miles away, revealing a big snowball of dirty ice and rock. Last week, scientists processed the first images of the comet's bright core taken from 20 million miles away, which should help the probe zero in on its target.
The real action starts in the early morning of July 3 (Eastern time) when the spacecraft separates, releasing an 820-pound copper probe called the "impactor" on a one-way trip straight into the path of the comet. During the next 22 hours, mission control at Jet Propulsion Lab in Pasadena will steer both craft toward Tempel 1.
Two hours before the July 4 encounter, the impactor kicks into autopilot, relying on its self-navigating software and thrusters for the rest of the journey to steer toward the sunlit part of the comet's nucleus so that space and Earth-based telescopes can get the best view.
Meanwhile, the spacecraft - with its high-resolution camera ready - will veer out of harm's way some 5,000 miles away, as it stakes out a ringside seat for recording the collision. The spacecraft will make its closest fly by minutes after impact, approaching within 310 miles.
The collision is expected to occur around 1:52 a.m. EDT when the comet, traveling through space at 6 miles per second, runs over the impactor, which will be shooting some of the most close-up pictures of Tempel 1 up until its death.
Grammier has likened it to standing in the middle of the road and being hit by a semi-truck going 23,000 mph - "you know, just bam!" The energy produced by the crash will be like detonating nearly 5 tons of TNT.
The high-speed collision is expected to excavate a crater that can range anywhere from the size of a house to a football stadium, and from two to 14 stories deep. A spew of ice and dust debris will likely shoot out from the newly formed hole, possibly revealing a glimpse of the comet's core.
Scientists say if the comet is porous like a sponge, the impact should produce a stadium-sized crater about 150 feet deep and 650 feet wide. This suggests that the comet's inside holds some of the pristine material of the early solar system.
But if the comet is packed like a snowball, the crater formed would be much smaller. Another scenario is that the comet is so porous that most of the impactor's energy is absorbed, creating an even smaller but deep crater.
The mothership has less than 15 minutes to snap images from the cosmic collision and resulting crater before it's bombarded with a blizzard of debris. Scientists expect to receive near real-time data from the impactor and spacecraft.
"We get one chance," said Michael A'Hearn, a professor of astronomy at the University of Maryland and Deep Impact principal investigator.
|Hubble spies comet Tempel 1 belching dust|
Monday, June 27, 2005
WASHINGTON -- The volatile nucleus of comet Tempel 1 blew off a stream of dust that was captured in an image by the Hubble Space Telescope, scientists said on Monday.
The dust jet could be a preview of what astronomers see on July 4, when NASA's Deep Impact space probe is set to collide with the comet, giving the first glimpse inside the heart of a comet, the scientists said in a statement.
The collision on the comet could cause a similar dust plume on Tempel 1's surface.
Hubble captured the images when it was 75 million miles (120 million km) away from Tempel 1. The orbiting telescope's views complement close-up pictures being captured by Deep Impact's cameras as it speeds toward the comet.
The two images snapped by Hubble were taken seven hours apart on June 14. One shows a view of the comet before the outburst; the other shows the jet, which extends about 1,400 miles (2,200 km).
Comets often show bursts of activity, but astronomers do not know why. It might be because Tempel 1 is moving closer to the sun and the increased heat could have opened up a crack in the comet's crusty surface, allowing trapped dust and gas to escape.
Another theory is that part of the comet's crust lifted off the nucleus because of the pressure of heated gases beneath the surface, and the crust may have quickly crumbled into small dust particles, producing a fan-shaped jet.
Astronomers hope the July 4 smashup will release more primordial material trapped inside the comet, which formed billions of years ago.
Comets are thought to be "dirty snowballs" made up of ice and rock.
Comment: In other words, scientists really don't have a clue what's going to happen when the the Deep Impact probe smashes into Tempel 1...
|The Origins of Doomsday Anxiety|
June 14, 2005
After years of ignoring the most pervasive fear in human history, it is time to examine its roots dispassionately. For such a purpose, we need only call upon the appropriate rules for evaluating historical evidence.
Let a comet appear in the sky. Let the "zeroes" line up on a calendar. Let the weather turn stormy, or world events grow unsettled. When such things occur they will invariably trigger a cultural response - the "doomsday anxiety", a fear of the end of the world.
Today little attention is given to the historic origins of this cultural syndrome. However, only a few years ago it reared its head at the turn of the millennium. And just two years earlier we saw it with the dramatic appearance of the comet Hale Bopp. Within various religious cults, preachers and gurus and wild men have pointed to imminent apocalypse for as long as any of us can remember.
Indeed, the phenomenon may seem too trivial to merit concern. We easily dismiss it as a minor demonstration of the irrational in our species. But the historic nature of the anxiety does deserve attention, for no archaic culture was free from the fear of Doomsday. And most of the collective investment in ritual and magic bore a direct connection to the mythology of overwhelming catastrophe.
Early mythic and religious traditions reveal many fears, beliefs, and yearnings shared by all of the early cultures. But while many of the motives are universal, the experiences to which they refer are beyond the ability of accepted science and theory to explain. Science today has no frame of reference for dealing with the collective memories that drove the early cultures.
At the end of a 52-year calendar cycle, Aztec priests would anticipate a world-ending conflagration. On seeing that the heavens remained as they were, the people would celebrate the new lease on life. Moreover, the theme of cosmic upheaval appears in New Year's festivals around the world. Our own Halloween, Christmas, New Year, and May Day celebrations have preserved many fragments. The prototypes for these occasions lay in the remote past, in such celebrations as the Egyptian Sed Festival and the Babylonian Akitu festival, both harking back to events of cosmic chaos and destruction.
It is no overstatement to say that ancient nations the world over were obsessed with ideas of world-ending disaster. But here is the heart of the matter, the one fact that can explain the Doomsday anxiety both ancient and modern. Humans everywhere on earth once remembered a world-altering catastrophe, an event of such devastating intensity that it hung like a cloud over every culture for thousands of years. And what they remembered, they expected to happen once more. As before, so again.
The world-ending catastrophe remembered by Nordic cultures gave rise to the prophetic vision of Ragnarok, the destruction of the world in a rain of fire and stone. In this vision the great serpent Jormungand rises from the waters of the deep and attacks, spitting its fiery venom upon the world. A battle ensues between gods and giants. Odin's dark angels, the Valkyries, ride their steeds across the sky, their golden hair streaming behind them. The walls of the heavenly city Asgard fall down, and the celestial bridge of Bifrost dissolves in flames.
A much earlier account of universal disaster, preserved by the Greek poet Hesiod, described the "clash of the Titans". On one side, the leader of the Titans was the god Kronos, original ruler of heaven; on the other, his own son, Zeus. Their war in the sky brought the world to the edge of complete destruction.
"For a long time now, the Titan gods and those who were descended from Kronos had fought each other, with heart-hurting struggles, ranged in opposition all through the hard encounters," wrote Hesiod. The upheaval lasted for ten years, culminating in a heaven-shattering conflagration, when the whole world shuddered beneath the thunderbolts of the gods. The celestial combatants "threw their re-echoing weapons and the noise of either side outcrying went up to the starry heaven as with great war crying they drove at each other."
To witnesses of the events, "it absolutely would have seemed as if Earth and the wide Heaven above her had collided, for such would have been the crash arising as Earth wrecked and the sky came piling down on top of her, so vast was the crash heard as the gods collided in battleÖ." Huge boulders flew between the celestial combatants. The roaring wind and quaking earth brought with them a great dust storm "with thunder and with lightning, and the blazing thunderbolt, the weapons thrown by great Zeus."
In such descriptions as these the gods do not just disturb the earth with their thunderbolts, they pound each other with them amid horrific sound, earthquake, raging wind, and a devastating fall of rock.
The notion that archaic memories of universal catastrophe were simply exaggerated accounts of local disasters is an unsupportable oversight in specialized cultural study today. Specialists have suggested that the world of the first storytellers was so limited it was "only natural" that they would experience a local flood or a particularly destructive volcanic eruption as a world-ending conflagration. But this gratuitous supposition is contradicted by a cross-cultural coherence.
To reconcile human memories and scientific evidence, it is not sufficient to dismiss the ancient witnesses when their testimony is incompatible with today's "scientific mythology." The essential requirement is that appropriate ground-rules be followed for assessing cross-cultural evidence. Ancient testimony is both unreliable and useless when individual stories are considered in isolation. No one will ever penetrate to the original human experience by studying a local legend in North America or the South Pacific. But human testimony can be extraordinarily reliable in the hands of one attentive to the points of agreement - particularly where extraordinary and unexpected details are repeated around the world.
In its every nuance the Doomsday theme declares that our theoretical assumptions are not correct. But ideology has prevented accredited specialists from following the most obvious question: Does the occurrence in every culture of the same themes and details, which are unnatural in today's world, indicate an archaic experience of a world with a different nature? Certainly no Egyptologist or Sumerologist could know, based on his specialized learning, whether cosmic violence punctuated the recent history of the solar system. But the supposition of a changeless solar system has kept specialists from comparing data and asking the question.
The worldwide Doomsday theme has no roots in familiar natural events. Therefore, we cannot ignore the direct implication: the myths arose as imaginative interpretations of extraordinary occurrences. If mankind's Doomsday anxiety was provoked by events no longer occurring, the conventional historians' dismissive approach to the subject must be counted among the greatest theoretical mistakes of modern times.
|Ball of flame in the sky|
Wednesday, June 29, 2005
A ball of flame was spotted in the Mayo sky at 1.46 a.m. on Sunday night/ Monday morning, writes Michael Commins. The light, which was low down in the northern sky, was travelling in a north easterly direction and falling rapidly towards earth. The object may have been a meteorite or object burning up on entering the earth's atmosphere.