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Of Cosmic Rays and Dangerous Days
Of Cosmic Rays and Dangerous Days
By Phil Berardelli
ScienceNOW Daily News, 1 August 2007
Researchers may have uncovered the reason why Earth's biodiversity
mysteriously plummets periodically. They have found that a
rollercoaster-like wobble in the sun's orbit around the center of the Milky
Way galaxy regularly moves Earth closer to a source of dangerous
intergalactic cosmic rays.
Over the last 500 million years or so, the number of species on Earth has
tended to dip regularly about every 62 million years. The last time this
happened, about 55 million years ago--or about 10 million years after the
great K-T extinction event that wiped out the dinosaurs--biodiversity sank
by about 10%; around 115 million years ago, it dropped by a similar amount.
So far, evolutionary biologists have only been able to establish that the
phenomenon seems cyclical, but they haven't isolated a cause.
Now, researchers from the University of Kansas in Lawrence think they have
found a possible answer...
Read more at:
http://sciencenow.sciencemag.org/cgi/content/full/2007/801/1
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Dann Pigdon
GIS / Archaeologist geo cities.com/dannsdinosaurs
Melbourne, Australia heretichides.soffiles.com
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