Only 10 million more years until we all get fried by cosmic radiation

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Only 10 million more years until we all get fried by cosmic radiation

Every 62 million years life on earth gets fried by cosmic radiation.
... Quote:
There are 62-million-year ups and downs in the number of marine animals over the last 550 million years.

Until now, however, even the scientists who first discovered the cyclical pattern had not been able to explain it.

Melott said.

The Kansas 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.

"Excursions to galactic north coincide with drops in biodiversity," Melott said.

During these periods, which include some of the largest mass extinctions known from the fossil record, Earth is bombarded with high levels of cosmic radiation.

The radiation may harm biodiversity by causing mutations or by triggering climate change, the researchers said.

Our solar system travels through the disk-shaped Milky Way on a complicated circuit that takes about 225 million years to complete.

At regular intervals, the system's wanderings take it up and down through the thin central portion of the disk. The sun reaches its farthest distance from the central plane every 62 million years.

The entire galactic disk, meanwhile, is hurtling through the hot gas that surrounds it at about 125 miles (200 kilometers) a second.

"The movement [of the Milky Way] is not edge-on like a Frisbee," Melott noted. Instead, he said, it is flat, "like a pie in the face."

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.

As the solar system rises above the central plane it sticks out like a cherry on top of the flying galactic pie—closer to the source of the cosmic radiation.

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By netchicken: posted on 23-4-2007








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