Explanation: In 1993, a star in the galaxy M81 exploded. Above is a picture of the hot material ejected by this supernova explosion. The picture was taken in X-rays with the Advanced Satellite for Cosmology and Astrophysics (ASCA). Since M81 is a relatively nearby galaxy, it can be examined in close detail by observatories on or near the Earth. Since the Earth's atmosphere protects the surface from interstellar X-radiation, the above photo was taken from space. Studying the nature and distribution of the X-rays has allowed astronomers to determine the composition and temperature of the expanding supernova gas.

Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
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