This helmet-shaped cosmic cloud with wing-like appendages is popularly called Thor’s Helmet. Heroically sized even for a Norse god, Thor’s Helmet is about 30 light-years across. In fact, the helmet is more like an interstellar bubble, blown as a fast wind from the bright, massive star near the bubble’s center sweeps through a surrounding molecular cloud. Known as a Wolf-Rayet star, the central star is an extremely hot giant thought to be in a brief, pre-supernova stage of evolution. Cataloged as NGC 2359, the nebula is located about 15,000 light-years away in the constellationCanis Major. The sharp image, made using broadband and narrowband filters, captures striking details of the nebula’s filamentary structures. It shows off a blue-green color from strong emission due to oxygen atoms in the glowing gas.

NGC 2359 (also known as Thor’s Helmet) is an emission nebula in the constellation Canis Major. The nebula is approximately 3,670 parsecs (11.96 light years) away and 30 light-years in size. The central star is the Wolf-Rayet star WR7, an extremely hot giant thought to be in a brief pre-supernova stage of evolution. It is similar in nature to the Bubble Nebula, but interactions with a nearby large molecular cloud are thought to have contributed to the more complex shape and curved bow-shock structure of Thor’s Helmet. It is also catalogued as Sharpless 2-298 and Gum 4.