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Sea life possiblly killed by Gamma ray burst
[Link mogu videti samo ulogovani korisnici] 2005-04-11 11:28:29
BEIJING, April 11 (Xinhuanet) -- A huge blast of radiation from an exploding star may have wiped out much of life in the sea around 450 million years ago, scientists claim.
In the latest issue of the Astrophysical Journal Letters, scientists argue that a gamma ray burst, the most powerful explosion that occurs in the universe, was responsible for the Ordovican mass extinction in which 60% of all marine invertebrates died.
Gamma ray bursts are hugely powerful surges of radiation. Gamma ray bursts are thought to be caused either when two neutron stars collide or when giant stars collapse into black holes at the end of their lives.
Such a burst would strip the Earth of its protective ozone layer, allowing deadly ultraviolet radiation to pour down from the Sun.
Marine life which lived at deeper levels would probably have survived the gamma blast, say the scientists.
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