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[Science] Explosions in Space

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spiegel    0
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.

Gamma-ray bursts in our Milky Way galaxy are indeed rare, but the scientists estimate that at least one nearby likely hit the Earth in the past billion years. Life on Earth is thought to have appeared at least 3.5 billion years ago. This research, supported by a NASA Astrobiology grant, represents a thorough analysis of the "mass extinction" hypothesis first announced by members of this science team in September 2003.

"A gamma-ray burst originating within 6,000 light years from Earth would have a devastating effect on life," said Dr. Adrian Melott of the Department of Physics and Astronomy at the University of Kansas. "We don't know exactly when one came, but we're rather sure it did come -- and left its mark. What's most surprising is that just a 10-second burst can cause years of devastating ozone damage."

112093main_extinctfinal_lgweb.jpg

Image above: Scientists say that a ten-second burst of gamma rays from a massive star explosion within 6,000 light years from Earth could have triggered a mass extinction hundreds of millions of years ago. In this artist's conception we see the gamma rays hitting the Earth's atmosphere. (The expanding shell is pictured as blue, but gamma rays are actually invisible.) The gamma rays initiate changes in the atmosphere that deplete ozone and create a brown smog of NO2.

With the ozone layer damaged for up to five years, harmful ultraviolet radiation from the Sun would kill smaller life-forms and disrupt the food chain. Scientists say that a gamma-ray burst might have caused the Ordovician extinction 450 million years ago, some 200 million years before dinosaurs. Image Credit: NASA

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whats scary is the thought that we might not create our extinction, rather its gonna come from a wave that will disrupt the natural order :blink:

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vincent    154
112093main_extinctfinal_lgweb.jpg

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whats scary is the thought that we might not create our extinction, rather its gonna come from a wave that will disrupt the natural order :blink:

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:whistle:

http://www.neowin.net/forum/index.php?showtopic=321658&hl=

The likelihood of this is lower compared to when our planet and galaxy was younger. but if a star (closeneough) was to die and cause a supernova explosion (resulting from exhausting it's supply of nuclear fuel, and collapsing under it's own gravitational force) then yea we'd be screwed, luckily it will be a quick death for planet earth.

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spiegel    0

alright thats it ill stop making science threads!

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ev0|    2

That was a hell of a cool picture !

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Argote    73

GRB's (gamma ray bursts) seem to always be found in far away places (meaning it happened a long time ago) im thinking they are far less common nowadays than when the universe was young

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