Cosmic-Ray Cycles Trigger Mass Extinctions
Earth has seen five major extinctions in it's 4.5 billion year history, the last and biggest the Permian about 245 million years ago, which dropped the curtain on the dinosaurs along with 95 percent of animal species known from the fossil records.
University of Kansas researchers have concluded that cosmic rays produced at the edge of our galaxy have devastated life on Earth every 62 million years. The researchers discovered that high rates of extinction in the cycle coincide almost perfectly with periodic "excursions" of the solar system outside the central plane of the Milky Way galaxy.
The new theory suggests that cosmic rays are continually generated in a shock wave produced where the galaxy's "northern" or forward side collides with surrounding gases. Earth is exposed to the shock front more when it's emerging on the north side of the galactic disk. The researchers said, however, that their model does not explain all major mass extinctions. The next cosmic ray effect is about ten million years ahead in the future.
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"Great Extinction" & the Rise of Modern Species
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