About This Photograph
Also known as NGC 6888, Caldwell 27, and Sharpless 105, the Crescent Nebula is about 5,000 light years away in the constellation of Cygnus, high overhead in summertime in the northern hemisphere. This expanding cloud of gas was produced by the bright star near the center, a rare Wolf-Rayet star near the end of its life. Long ago, as a red giant, it shed its outer layers into the surrounding space. Now completely depleted of hydrogen fuel, the star fuses helium in its core and expels an energetic stellar wind that collides with the earlier material, shocking it into luminescence.
This photograph was taken using two special filters that isolate light from hydrogen (red) and oxygen (blue-green).
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