Photo: NGC 2359, aka Thor’s Helmet Nebula, taken using broadband and narrowband filters | Adam Block, Mt. Lemmon Sky Center/University of Arizona
NGC 2359, or Thor’s Helmet Nebula, is an emission nebula1 located in the constellation Canis Major, the Great Dog. With its round shape and wing-like filamentary structures, this visually stunning nebula bears a striking resemblance to the helmet worn into battle by Thor, the well-known Norse god of thunder.
Thor’s Helmet spans a staggering 30 lightyears across, making it more than 10 times larger than our entire solar system. It lies approximately 3,670 parsecs (11.96 thousand lightyears) away from Earth. It contains several hundred solar masses, At its core is WR7, an extremely hot Wolf-Rayet star2 thought to be over 280,000 times brighter than our Sun and 16 times more massive.
1 A nebula formed of ionized gases that emit light of various wavelengths.
2 Rare, super-bright stars that exhibit a large burst of activity before they die.