NGC 2359, better known as the Thor's Helmet nebula, is actually 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. The central star is an extremely hot giant Wolf-Rayet star, thought to be in a brief, pre-supernova stage of evolution. It lies about 15,000 light years from Earth in the constellation Canis Major, measuring about 30 light years.
Thor’s Helmet Nebula - NGC 2359 (also known as Thor's Helmet) is an emission nebula in the constellation Canis Major. The nebula is approximately 15,000 light-years away and 30 light years in size. The central star is the Wolf-Rayet star HD 56925, an extremely hot giant thought to be in a brief, pre-supernova stage of evolution