Crescent Nebula

The Crescent Nebula, NGC6888, is one of the prominent emission nebulae in Cygnus, about 5000 light years away from Earth. It is associated with the Wolf-Rayet star WR136. When this star turned into a red giant about 100,000 years ago, it expelled its outer layers of gas, which slowly expanded into space. Today this gas is hit by the fast stellar wind from the star which shapes and energizes the cloud.

This is a bi-color narrowband composite image using a little over 5 hours of Ha and OIII data. One can already see an outer envelope with predominant OIII emission (in blue) around the finely structured inner part. The background also shows Ha emission (in red) from the vast nebulosity in Cygnus.