NGC 6888

The Crescent Nebula in Cygnus, NGC 6888, is an emission nebula about 5000 light years from Earth. The bright star in the center of the nebula is a Wolf-Rayet star, a massive star that is currently expelling a fast solar wind (about 3 million miles per hour) that has caught up with and is colliding with a slower wind (about 20,000 miles per hour) ejected by the star some 400,000 years ago when it was a red giant. The collision excites the gas and causes photon emission, revealing the shock wave from the impact. The star is in the last stages of its life and will explode as a supernova in another hundred thousand years or so.

Image taken July 25, 2012, with the C-14 operating at F:3.5 and the ST-8 camera binned 2 X 2. I stacked a clear frame with an H-Alpha frame to create a luminance frame for the LRGB combination. Total exposure was 25 minutes.