2013: Year in Space (31 images)

A look back on the years's launches, space explorations and discoveries.
Updated: Oct. 21, 2013 at 2:01 PM
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Stars can become remarkably photogenic at the end of their life, like NGC 2392, the "eskimo nebula", which is located about 4,200 light years from Earth. Planetary nebulas like NGC 2392, form when a star uses up all of the hydrogen in its core. When this happens, the star begins to cool and expand and the outer layers of the star are carried away by a thick 50,000 kilometer per hour wind, leaving behind a hot core with a surface temperature of about 50,000 degrees Celsius. The radiation from the hot star and the interaction of its fast wind with the slower wind creates the shell of a planetary nebula. Eventually the remnant star will collapse to form a white dwarf star. UPI/NASA
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