How Exploding Stars May Have Shaped Earth's History

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http://www.theatlantic.com/science/archi...th/490781/

EXCERPT: [...] One such change might have happened on Earth sometime between 1.7 and 3.2 million years ago. A star about nine times the mass of the sun blew up, and the night sky glowed a bright blue for weeks, during which the supernova outshone the full moon. Long after the darkness returned, lightning set off by cosmic rays would have arced from the sky to the ground, and the planet’s climate may have changed. Animals on land and in the shallow sea would have been doused with waves of radiation. Over time, the influx of particles could have sparked mutations in DNA, making small alterations that could have shifted the course of evolution.

From our vantage point on Earth, supernovae appear suddenly; their name comes from the word for “new star.” Their brilliant, visible shine fades away within a few days or weeks, but they continue firing a stupendous surge of x-rays, gamma rays and speedy, energetic particles for much longer. Only recently have astronomers brought these supernovae down to Earth, by wondering how they might have interfered with the planet’s climate, and the evolutionary processes that were playing out on its surface...
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