Thor's Helmet
Thor's Helmet (NGC 2359) is an emission nebula in the constellation Canis Major. It's 30 light years across and 3,660 light years from Sol.
The nebula was formed due the star WR 7 expelling its outer layers. The helmet shape is resulted from interaction of the expanding bubble of expelled material with giant molecular clouds in the area.
The large star located in the center is a Wolf-Rayet star WR 7 (HD 56925, HIP 35 378). This star is 280,000 times brighter than than Sol, 16 times more massive and 1.41 times bigger.
The name is due to its bubble shape and filaments that resemble the Norse god’s helmet.