APOD 3.6

Pictured above is a cosmic cloud with wing-like appendages that make the cloud appear much like it's name, Thor's Helmet. The cloud spans about  30 light years and 15,000 light years from Canis Major. It is described as more of an interstellar bubble than a cloud, that surrounds the Wolf-Rayet star in its center. The star is thought to be in a stage of pre-supernova. The greenish color comes from emission of oxygen atoms.