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Nearby Supernova Causes Mass Extinction?
hcg50a writes "AP has a
story on Yahoo about a theory that a blast of gamma rays from a distant supernova destroyed the earth's ozone layer, allowing normally shielded intense UV radiation from the sun to kill life on earth. The second-largest extinction in the Earth's history, the killing of two-thirds of all species, may have been caused by ultraviolet radiation from the sun after gamma rays destroyed the Earth's ozone layer. Astronomers are proposing that a supernova exploded within 10,000 light years of the Earth, destroying the chemistry of the atmosphere and allowing the sun's ultraviolet rays to cook fragile, unprotected life forms."
They should have been using sun-bloc SPF-10,000,000
I'm not sure if other hard-sci-fi authors have addressed this, but Stephen Baxter's Manifold Space used a theory like this to address the Fermi Paradox: if we assume that physical laws are constant throughout the universe, why hasn't there been contact with other species? His answer? A sort of galactic reset.. When conditions are just right, two neutron stars (or other heavy bodies) will enter a decaying orbit, and release gravitational energy in the form of gamma rays (I believe.) In short, resetting the biological clock of our galaxy. Different from destroying the ozone layer, but this article makes it seem a little less far fetched, doesn't it?
This statement is false.
The article clearly states that they have no real evidence to speak of. The only thing they do have is the ice age that occured at the time of the extintion. They admit that no traces of a supernova near earth can be found, and blame it on the rotation of the Milky way.
Melott said there is no known evidence of such a nearby supernova, but that in 440 million years the Milky Way would have rotated almost twice and traces of the explosion could have been moved during that time.
I will give them that it is a possibility, but until they have some more convencing evidence I'm not ready to jump aboard.
You're right. Our sun is a dwarf star. It's death will be marked by expansion into a giant red star, then compression into a small core of oxygen and carbon, and finally lights out. Check out the BBC's page on the death of stars.
and here's the ticking time bomb within 10,000 lightyears that's going to finish us off. It may in fact already have supernovaed, and the gamma ray clam-bake coming at lightspeed! Oh, and recently revised estimates indicate no more than 20,000 years to the big pop. This will mess up your hard disk.