English: Thor’s Helmet spans about 30 light-years across and is approximately the size of the full moon in the sky. The helmet is an interstellar bubble where the solar wind from bright star near the center of the bubble’s blue-hued region sweeps through the surrounding molecular cloud and expands the gas. This star, a Wolf-Rayet, is a massive and extremely hot giant star thought to be in a brief, pre-supernova stage of evolution. Cataloged as NGC 2359, the emission nebula is located about 12,000 light years away toward the constellation of the Big Dog (Canis Major). The image, made using narrowband filters, captures details of the nebula’s filamentary gas and dust structures. Hydrogen is red in the image and the blue green color originates from strong emission from oxygen atoms in the nebula. While the image is technically a false color image it is close to the actual colors of the emitting light.The image is a composite of 47 images taken over 16 hours using a Planewave 20" telescope and a Finger Lakes Instruments PL16803 camera.