The Crescent Nebula

NGC 6888, the Crescent Nebula is an emission nebula in the Cygnus constellation, about 5000 light years away.
The Crescent Nebula began to form about 250,000 years ago as central Wolf-Rayet star WR 136 began to shed its outer envelope in a strong stellar wind, expelling the equivalent of our Sun's mass every 10,000 years.