Gamma Ray Bursts May Have Caused Mass Extinction |
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Written by spacetravel.org
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Wednesday, 27 July 2005 21:52 |
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A gamma ray bust (GRB) may have caused the Ordovician extinction, a mass extinction 443 million years ago, which killed off 60 percent of marine invertebrates.
Researchers from the University of Kansas and NASAs Goddard Flight Center modelled the effect a GRB would have on the Earths atmosphere. They discovered that a typical GRB, taking place within a few thousand light-years from Earth, would generate enough gamma rays to wipe out half the Earths ozone layer. This would allow more ultraviolet light to reach the surface, killing off many species of plants and animals on the surface. Most deep sea life would be unharmed. There is no direct evidence that a GRB has caused any mass extinctions.
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