Sunday, April 10, 2005

433: Space Explosions May Have Initiated Extinction on Earth | Science Blog

Space Explosions May Have Initiated Extinction on Earth | Science Blog:

Scientists at NASA and the University of Kansas say that a mass extinction on Earth hundreds of millions of years ago could have been triggered by a star explosion called a gamma-ray burst. The scientists do not have direct evidence that such a burst activated the ancient extinction. The strength of their work is their atmospheric modeling -- essentially a "what if" scenario.

The scientists calculated that gamma-ray radiation from a relatively nearby star explosion, hitting the Earth for only ten seconds, could deplete up to half of the atmosphere's protective ozone layer. Recovery could take at least five years. With the ozone layer damaged, ultraviolet radiation from the Sun could kill much of the life on land and near the surface of oceans and lakes, and disrupt the food chain.

Dr. Bruce Liebermann, also of KU, started the idea that the Ordovician extinction was triggered by a gamma ray burst. This research is inspired by evolutionary biology, and generates testable hypotheses. Ongoing space missions will gather vital data, and paleontological data will test claims about past events.