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Posted on 04/02/2006 2:13:59 PM PDT by SunkenCiv
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Oh NO! Not the wobblies again!
Huge Space Clouds May Have Caused Mass ExtinctionsThe idea that we pass through clouds of galactic debris is not new. In fact, a 2003 study found that we're traveling through a mild one right now... The dust layer would hover around Earth, reducing the amount of sunlight reaching the planet while letting terrestrial heat escape into space, creating a snowballing chill. "There are indications from 600 to 800 million years ago that at least two of four glaciations were snowball glaciations," Pavlov said. "The big mystery revolves around how they are triggered." Moderately dense space clouds, the sort that might destroy the ozone layer, are huge, Pavlov points out, and the solar system could take up to 500,000 years pass through one. Extra cosmic rays produced during such an event, owing to interactions of the interstellar dust with the Sun, would break up nitrogen molecules in Earth's atmosphere, leading to ozone destruction... Geologists could look for higher amounts of uranium 235 in soil layers corresponding to the time of known glaciations. Uranium 235 can't be produced naturally in the solar system.
by Robert Roy Britt
March 4, 2005
Evidence Of Meteor ImpactMost scientists agree a meteor impact, called Chicxulub, in Mexico's Yucatan Peninsula, accompanied the extinction of the dinosaurs 65 million years ago. But until now, the time of the Great Dying 250 million years ago, when 90 percent of marine and 80 percent of land life perished, lacked evidence and a location for a similar impact event. Becker and her team found extensive evidence of a 125-mile-wide crater, called Bedout, off the northwestern coast of Australia... During recent research in Antarctica, Becker and her team found meteoric fragments in a thin claystone "breccia" layer, pointing to an end-Permian event. The breccia contains the impact debris that resettled in a layer of sediment at end-Permian time. They also found "shocked quartz" in this area and in Australia... Quartz can be fractured by extreme volcanic activity, but only in one direction. Shocked quartz is fractured in several directions and is therefore believed to be a good tracer for the impact of a meteor... The Bedout impact crater is also associated in time with extreme volcanism and the break-up of Pangea. "We think that mass extinctions may be defined by catastrophes like impact and volcanism occurring synchronously in time," Becker said. "This is what happened 65 million years ago at Chicxulub but was largely dismissed by scientists as merely a coincidence. With the discovery of Bedout, I don't think we can call such catastrophes occurring together a coincidence anymore," she added.
Found Off Australian Coast
by Donald Savage
May 13, 2004
The Suspect The Theory The Evidence The Proponents The Holes Asteroid impact A space rock strikes in the tropics, spews debris into the air and triggers lethal climate change Scientists found 250 million year old rocks from Antarctica and China said to contain meteorite fragments Researchers at the University of Rochester, Harvard, and UC Santa Barbara Scientists have yet to find the ultimate smoking gun, a crater Sudden methane explosion A massive cloud of methane gas abruptly bursts from the ocean, cataclysmic flooding and fires ensue Great Dying fossils show a sudden sharp rise in carbon-12 isotopes, best explained by a methane belch Chemical engineer Gregory Ryskin at Northwestern University The explosion requires an improbable 10,000 gigatons of methane Slow methane leak Volcanoes of frozen deposits leak methane over thousands of years, depleting oxygen The burrowing reptile Lystrosaurus, adapted for low-oxygen conditions, thrived during this period Researchers at the University of Oregon, the South African Museum, and the University of Washington The leak could not deplete enought oxygen to cause global death, critics say Hydrogen sulfide stink bomb Lethal levels of hydrogen sulfide, emitted by anaerobic bacteria, are expelled from the ocean into the air Proponents are searching for signs of sulfur bacteria in Japanese sediments dated to the extinction Scientists at Penn State, the University of Colorado, and the University of Tokyo There's no proof that the upper layers of ancient oceans were devoid of oxygen
search for Volcanoes "Randolph E. Schmid":Debate Stirs On Hotspot VolcanoesThe most common theory in recent years has been that hotspots exist in the Earth where molten lava wells up from deep below, creating volcanoes such as those that formed Hawaii and Iceland and seismic zones such as Yellowstone. But Gillian Foulger of the University of Durham, England, and James Natland of the University of Miami point out in the journal Science that efforts to find evidence of hotspots using seismic waves have not produced results... In a separate paper in the same journal, Donald J. DePaolo and Michael Manga of the University of California, Berkeley, agree that so far seismological studies searching for hotspots have not produced the expected proof. But they say they expect the evidence to be found. Theoretical and laboratory studies predict deep hot plumes, they note, and there is supporting evidence in the Hawaiian Island chain, with the rising lava building a line of islands as the overriding crust moves along, evidence of a stationary hotspot deep in the earth.
by Randolph E. Schmid
The Sky Isn't Falling, But Pieces Sure AreThe most spectacular visitor from beyond was a meteorite initially said to set a village afire in India and injure 20 people this past weekend. Later reports by the BBC and elsewhere put the injuries at three. The fireball streaking through the sky turned night into day, witnesses said. It was reported visible across a nearly 5,800-square-mile (15,000-square-kilometer) region. Two pieces about 11 pounds each (5 kilograms) were said to be recovered. On Monday, Sept. 29, a bright fireball startled residents around San Francisco. Witnesses said it flared several times over a few seconds before disappearing below the horizon, according to a report in the San Jose Mercury News... Peter Jenniskens, an astronomer with the SETI Institute and NASA's Ames Research Center, told the newspaper that the event had the markings of comet debris, which is more fragile than asteroid material and therefore more likely to break apart and generate a bright flare... Jenniskens said the fireball might have been part of an unexpected shower of debris. Another bright meteor had been spotted five hours prior from Europe, he said. Another bright and fiery object was seen in the night sky over Australia this past weekend, near the time of the Indian meteorite... One that did not fully vaporize hit Roy Fausset's recently renovated bathroom Sept. 23 in New Orleans.
by Robert Roy Britt
Thu Oct 2, 2003
Earth's Little Brother Found [2002 AA29]
BBC | 10-21-2002 | Dr. David Whetstone
Posted on 10/21/2002 2:37:19 PM PDT by blam
Cat-And-Mouse Asteroid Pulls Close To Earth [2002 AA29]
IOL | 1-3-2003
Posted on 01/04/2003 10:12:20 AM PST by blam
Odd Asteroid [2003 GQ22]
spaceweather.com | april-15-2003 | spaceweather.com
Posted on 04/15/2003 2:06:02 PM PDT by green team 1999
Say hello to our new moon [2003 YN17]
AFP | Fri Mar 26, 2004
Posted on 03/29/2004 12:13:58 PM PST by presidio9
Astronomy Picture of the Day 5-04-02 [3753 Cruithne mentioned in replies]
NASA | 5-04-02 | Robert Nemiroff and Jerry Bonnell
Posted on 05/04/2002 7:26:04 AM PDT by petuniasevan
Did Seafarers Map The WorldRivers -- even short, glacier-fed rivers -- in Antarctica? Geologists maintain that during the last ice age, ending about 10,000 B.C., Antarctic ice extended north to cover Patagonia, and then contracted to its present continental dimensions. So Piri Re'is's ice-free coasts and islands and Oronteus Finaeus' rivers had to be imaginary. Yet as Hapgood was to learn, cores taken in 1949 from the bottom of the Ross Sea, across Antarctica from Queen Maud Land, consisted, at depths laid down over many millennia ending by about 4000 B.C., of the fine-grained sediment washed down by rivers in temperate lands.
Long Before Columbus?
by Ormonde deKay Jr
and Richard Cravens
"Mysteries of the Past", p 185
In Renaissance maps of northern regions Hapgood found other puzzling features: an ice-free Greenland; the British Isles with glaciers covering their centers; a partly glaciated Sweden; the Aegean Sea dotted with numerous extra islands that had since been drowned, presumably, by the melting of ice further north; and the precisely drawn Pacific Coast of North America still connected by a land bridge to Asia.
Arizona meteor crater mystery solvedBy some calculations, the rock, an asteroid or a comet that crossed Earth's path, should have hit the ground at 72,000 kilometres per hour, for it left a huge crater 1.2 kilometres across and 150 metres deep.
Friday, 11 March 2005
If so, the high-velocity collision should have released so much heat that the iron-rich impacting rock itself, or at least part of it, should have melted in a flash. But no substantial signs of melted mineral have ever been found there.
The reason, according to the new study: the rock was merely the largest chunk from a space bruiser that probably measured 42 metres across.
After entering Earth's atmosphere, the giant broke apart at an altitude of around 14 kilometres as it encountered a steadily denser atmosphere, whose pressure both cushioned the descent and caused the rock to fracture.
The fragments then descended in a pancake-shaped cluster, with atmospheric drag acting as a brake.
The piece that created Meteor Crater was probably around 20 metres across and hit the ground at 43,000 kilometres per hour, releasing the equivalent force of 2.5 megatons of TNT, or at least 150 times the "Little Boy" atomic bomb dropped on Hiroshima in 1945, the study suggests.
Comets And Disaster In The Bronze AgeThe hunt for natural causes for these human disasters began when the Frenchman Claude Schaeffer, one of the leading archaeologists of his time, published his book Stratigraphie Comparee et Chronologie L'Asie Occidentale in 1948. Schaeffer analysed and compared the destruction layers of more than 40 archaeological sites in the Near and Middle East, from Troy to Tepe Hissar on the Caspian Sea and from the Levant to Mesopotamia. He was the first scholar to detect that all had been totally destroyed several times in the Early, Middle and Late Bronze Age, apparently simultaneously. Since the damage was far too excessive and did not show signs of military or human involvement, he argued that repeated earthquakes might have been responsible for these events.
by Dr Benny J Peiser
Journal of the Council for British Archaeology
(link from Justa in Catastrophic event preceded Dark Ages - scientist)
The Day the World BurnedThe cataclysm went far beyond the regular insults from which living things must recover. The asteroid or comet flashed through the sky more than 40 times as fast as the speed of sound. It was so large that when its leading edge made contact with ground, its trailing edge was at least as high as the cruising altitude of a commercial airliner. It produced an explosion equivalent to 100 trillion tons of TNT, a greater release of energy than any event on our planet in the 65 million years since then... The crater, called Chicxulub after modern Maya villages in the area, is approximately 180 kilometers in diameter and is surrounded by a circular fault 240 kilometers across, apparently produced when the crust reverberated with the shock of the impact...
by David A. Kring
and Daniel D. Durda
November 27, 2003
New crater revives Moon mysteryA mysterious flash on the Moon caught on camera 50 years ago is still provoking disagreements about its origin. Astronomer Bonnie Buratti says her new results show that the flash was caused by a 20-metre asteroid hitting the Moon... Amateur astronomer Leon Stuart's 1953 photograph of the Moon shows a light spot near the centre of the Moon's visible surface. It would take a half-megaton explosion to produce such a flash, says Buratti, of NASA's Jet Propulsion Laboratory at Pasadena.
by Jeff Hecht
11 January 2003
The resulting crater would not be visible from Earth, but it should appear on close-ups taken by lunar probes. In a future issue of the journal Icarus, Buratti reports a fresh impact scar at the site of the 1953 flash on images collected by the Clementine spacecraft as it orbited the Moon in 1994. A bright blanket of ejected material covers an area that is about 1.5 kilometres across, and the colour of the debris indicates that the crater is relatively new.
Comet blasts created Saturn's many moonsThe dozen small distant moons of Saturn discovered in 2000 are pieces of larger bodies shattered by cometary impacts, say planetary scientists. Researchers already knew that the new moons must have been captured as the planet formed because they have irregular orbits that keeps them 10 to 20 million kilometres from Saturn. But it now appears that the six to 32 km bodies are only fragments of the original objects... Two groups formed when comets demolished larger, captured moons. The other was formed when a one to three kilometre comet blasted chunks of Phoebe, a 220-km satellite of Saturn, into orbit... The idea of catastrophic cometary impacts on moons is not new. Earlier work indicated that some small inner moons, such as Miranda, reassembled themselves after being shattered by collisions... The Earth's lone Moon has probably survived destruction because comet impacts are much less common in the inner Solar System.
by Jeff Hecht
11 July 2001
Iridium-rich layers and catastrophismKyte et al have discovered a 2.3-million year-old sedimentary layer under the Antarctic Ocean that contains iridium and gold concentrations comparable to those in the Cretaceous-Tertiary boundary. The noble metals are mostly contained in millimeter-sized grains that resemble ablation debris from a large extraterrestrial object. Unlike the Cretaceous-Tertiary episode, however, the newly found layer is not accompanied by evidence of mass biological extinctions.
William R. Corliss
No. 18: Nov-Dec 1981When Antarctica Was GreenPeter Webb and his coworkers have found pollen and the remains of roots and stems of plants in an area stretching some 1300 kilometers along the Transantarctic Mountains. The Antarctic wood is so recent that it floats and burns with ease. Webb's group postulates that a shrub-like forest grew in Antarctica as recently as 3 million years ago... Nevertheless, these deposits of fresh-looking wood do suggest that trees recently grew only 400 miles from the South Pole. Also of interest is the fact that the sedimentary layers containing the wood have been displaced as much as 3000 meters by faults, indicating recent large-scale geological changes.
William R. Corliss
No. 45: May-Jun 1986An Antarctic Bone BedW. Zinsmeister was accustomed to scoff at the idea that the Age of Dinosaurs ended violently with the impact of a giant asteroid some 65 million years ago. He always asked: "Where's the layer of burnt and twisted dinosaur bones?" His certainty was shaken, however, when he began mapping fossil deposits on Seymour Island, Antarctica. He didn't find the dinosaur bones but rather a giant bed of fish bones at least 50 square kilometers in area. Some sort of catastrophe must have annihilated untold millions of fish. And guess what? This great bone bed was deposited directly on top of that layer of extraterrestrial iridium that marks the 65-million-year-old Cretaceous Tertiary boundary at many sites around the world.
William R. Corliss
No. 104: Mar-Apr 1996
Astronomy Picture of the Day 10-17-03
NASA | 10-17-03 | Robert Nemiroff and Jerry Bonnell
Posted on 10/17/2003 5:32:24 AM PDT by petuniasevan
Mystery Asteroid, Hermes, May Have a Partner
Space.com (Yahoo!) | 10/21/2003 | Robert Roy Britt
Posted on 10/23/2003 1:58:58 PM PDT by Pyro7480
Asteroid fragments on a fast collision courseOver a million large asteroids, each several kilometres wide, are orbiting the Sun in a belt between Mars and Jupiter. There are sometimes violent collisions... Collisions in the Asteroid Belt result in the asteroids being completely destroyed and shattered into countless pieces. Computer simulations predict that most of these fragments will eventually fall into the Sun. Some of them, however, will hit the Earth after millions of years as meteorites... Collisional fragments from asteroids in space are constantly being hit by cosmic radiation. This creates noble gases from nuclear reactions. These gases do not enter into any further chemical reactions. Therefore, during the entire duration of the radiation, i.e., the travel time of the fragment in space, they accumulate in the fragment. After measuring the concentration of these so-called cosmogenic inert gases, the travel time from original body to Earth can be calculated. The higher the concentration, the longer the meteorite was underway... The researchers used meteorites for their tests that are assumed to be the results of a huge asteroid collision in the recent history of the solar system. These meteorites were found in a stone quarry in southern Sweden in a 480 million year old seabed deposit... With the new method, it could be proven for the first time that the noble gases in the meteorites in southern Sweden were already in the meteorites 480 million years ago. The calculated travel time was reduced to a few hundred thousand years, which corresponds to the lower limits predicted by the computer simulations. These were the first fragments to arrive on Earth after a great collision. The short radiation age is a clue that the collision took place in the proximity of an orbital resonance in the Asteroid Belt. In addition, it could be proven that the fossil meteorites from southern Sweden all stem from the same event. The newly developed method from the Institute for Isotope Geology makes it possible to confirm the theories about the behaviour of asteroid fragments in space. This will make it significantly easier for researchers to predict future collisions with our planet.
Philipp Reza Heck
Prof. Rainer Wieler
July 14, 2004
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