December 19, 2011
Earth Safe And Sound From Supernova In 2012: NASA
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NASA reported recently that astronomers can say with certainty there is no fear of a supernova being close enough to hurt Earth, especially by 2012.Astronomers believe that about one or two supernovae explode each century in our galaxy. However, for Earth's ozone layer to experience damage from a supernova, the blast must occur less than 50 light-years away.
All of the nearby stars capable of going supernova are much farther than 50 light-years.
A gamma-ray burst (GRB) is an explosive event associated with supernovae that is capable of reaching Earth.
Some of these bursts are directed toward Earth, orbiting satellites detect a burst of highly energetic gamma rays somewhere in the sky.
"These bursts occur almost daily and are so powerful that they can be seen across billions of light-years," NASA said in a press release.
GRBs could affect Earth in the same way as a supernova, but only if its jets are directly pointed toward our planet.
Astronomers believe that a gamma-ray burst could affect Earth from up to 10,000 light-years away with each separated by about 15 million years. The closest burst on record was 1.3 million light-years away.
"As with impacts, our planet likely has already experienced such events over its long history, but there's no reason to expect a gamma-ray burst in our galaxy to occur in the near future, much less in December 2012," NASA said.
Image Caption: Supernova 1987A was the closest exploding star seen in modern times. It occurred in the Large Magellanic Cloud, a small galaxy that orbits our own Milky Way. Images taken by NASA's Hubble Space Telescope were combined to make this composite of the blast's expanding debris. Credit: NASA / ESA / P. Challis and R. Kirshner (Harvard-Smithsonian Center for Astrophysics)
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