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Gamma-Ray Bursts IV

April 21, 2016

A few years ago, the light from an exploding star reached Earth. For about a minute, the star was bright enough to see with the unaided eye. What makes that so impressive is that the star was seven-and-a-half billion light-years away. Even more impressive is that the star was many times brighter at other wavelengths — especially in gamma rays, the most powerful form of light. For a few minutes, the star was brighter than the combined light of millions of galaxies.

This “gamma-ray burst” probably happened when the core of a massive star collapsed to form a black hole. Some of the gas in the star’s outer layers was heated to billions of degrees, then blasted into space from the star’s poles. One of these “jets” of gas aimed at Earth, producing the gamma-ray burst.

Because it was so far away, the burst had little effect on our planet. But it’s possible that closer gamma-ray bursts could be harmful.

Some research, for example, suggested that a burst that reached Earth more than 1200 years ago could have damaged our planet’s ozone layer, allowing harmful energy from the Sun and other stars to reach the surface.

And a burst 450 million years ago is one possible cause of a mass extinction that killed 80 percent of the life on Earth.

Today, no stars that are likely to produce gamma-ray bursts are close enough to Earth to cause a problem. Still, it’s possible that such a deadly outburst could hit our planet in the distant future.


Script by Damond Benningfield

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