Duck and Cover: Ancient Mass Extinctions Caused by Cosmic Radiation

Ancient Mass Extinctions Caused by Cosmic Radiation, Scientists Say:

"Cosmic rays produced at the edge of our galaxy have devastated life on Earth every 62 million years, researchers say."

Not all mass extinctions are explained by this theory. For example, the KT boundary event probably has another cause.

But what an interesting idea: our galaxy is moving "flat-faced", like a pie in a pie fight, relative to surrounding material. A shock wave is generated where galactic matter comes into contact with the surrounding hot gases, and cosmic radiation is generated at that same point.

Periodically on its 225-million-year galactic orbit, our solar system rises up out of the galactic plane, closer to the shock wave, where it is exposed to more of the incoming cosmic radiation than normal.

Researchers aren't sure about the consequences of the increased radiation. Greater ozone depletion may allow more of the radiation to reach the earth's surface and into its oceans. Other effects may include changes in cloud cover, etc.

One possibility is that organisms receive harmful doses of radiation from high-energy particles known as muons, which are produced by cosmic rays colliding with Earth's atmosphere.

"Cosmic rays themselves are not really that dangerous," said Medvedev. "They create [charged particles] that propagate down through the atmosphere—especially muons that can go below the sea level."