The Crescent Nebula (oka SH2-105) is an emision nebula in the constellation Cygnus, about 5000 light-years away from Earth, or 29,400 trillion miles away. It is formed by the fast stellar from the Wolf-Rayet star colliding with and energizing the slower moving wind ejected by the star when it became a red giant star around 250,000 to 400,000 years ago. The result of the wind collision is a shell and two shock waved, one moving outward and one moving inward. The inward moving shock wave heats the stellar wind to x-ray-emitting temperatures. The surrounding nebulosity is mostly hydrogen gas, indicated by its typical red color.
This particular image is comprised of 40 subs @ 300s, 53 subs @ 600s (730mins or 12+ hrs) and was calibrated using 60 dark frames, 60 bias frames, and 60 flat images.
