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Massive Asteroids Transformed The Earth's Surface |
 Apr 17 2006, 05:34 PM
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 Senior Member  Group: Members Posts: 2454 Joined: 8-July 05 From: NGC 5907 Member No.: 430  |
Review: Cosmic Collisions
--- The universe is replete with gigantic collisions, from impacting asteroids to merging galaxies. Craig Remillard reviews a new movie showing at the American Museum of Natural History that helps people better visualize some of the violent aspects of the cosmos. http://www.thespacereview.com/article/600/1 -------------------- "After having some business dealings with men, I am occasionally chagrined,
and feel as if I had done some wrong, and it is hard to forget the ugly circumstance. I see that such intercourse long continued would make one thoroughly prosaic, hard, and coarse. But the longest intercourse with Nature, though in her rudest moods, does not thus harden and make coarse. A hard, sensible man whom we liken to a rock is indeed much harder than a rock. From hard, coarse, insensible men with whom I have no sympathy, I go to commune with the rocks, whose hearts are comparatively soft." - Henry David Thoreau, November 15, 1853 |
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Apr 18 2006, 02:34 AM
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#47
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Senior Member Group: Members Posts: 1636 Joined: 9-May 05 From: Lima, Peru Member No.: 385 |
New Insight into Earth’s Early Bombardment
Researchers examined about 50 different melted rock samples collected by astronauts during the Apollo missions in the late 1960s and 1970s. Using radiometric dating techniques, they found that all but a few of the rocks were between 3.8 and 4 billion years old. Earth itself is about 4.5 billion years old. The central conclusion: Furthermore, many of the samples displayed different chemical "fingerprints," which suggests that they were formed from different meteorites and lunar rocks. "The evidence is clear that there was repeated bombardment by meteorites," said study team member Robert Duncan from Oregon State University. The paradox of meteorites: Another intriguing possibility, say Duncan and others, is that rather than being vehicles of death and destruction, meteorites carried life, or molecules important for the emergence of life, to Earth. Rodolfo |
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Jun 2 2006, 12:58 AM
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#48
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 Senior Member Group: Members Posts: 1887 Joined: 20-November 04 From: Iowa Member No.: 110 |
Big Bang In Antarctica: Killer Crater Found Under Ice
Planetary scientists have found evidence of a meteor impact much larger and earlier than the one that killed the dinosaurs -- an impact that they believe caused the biggest mass extinction in Earth's history. An ancient mega-catastrophe paved the way for the dinosaurs and spawned the Australian continent, new research suggests. The 300-mile-wide crater lies hidden more than a mile beneath the East Antarctic Ice Sheet. And the gravity measurements that reveal its existence suggest that it could date back about 250 million years -- the time of the Permian-Triassic extinction, when almost all animal life on Earth died out. http://www.sciencedaily.com/releases/2006/...60601174729.htm |
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