Molecular Cloud
A dense and cold region of interstellar space composed primarily of molecular hydrogen, serving as the birthplace of stars. The molecular cloud associated with NGC 346 is actively forming new stars.
Source: science.nasa.gov
APODs including "Molecular Cloud"
Thor's Helmet in H-Alpha
02/02/2006
Near picture center, the helmet-shaped structure with wing-like appendages is popularly called Thor's Helmet. Cataloged as NGC 2359, the striking nebula is located about 15,000 light-years away in the constellation Canis Major. The helmet is actually more like a cosmic bubble, blown as the wind from the bright, massive star near the bubble's center sweeps through the surrounding molecular cloud. Known as a Wolf-Rayet star, the energetic star is a blue giant thought to be in a brief, pre-supernova stage of evolution. The remarkable color composite combines broad and narrow band images - including a deep exposure recorded with an H-alpha filter. The H-alpha image traces the light from the region's glowing atomic hydrogen gas. Heroically sized even for a Norse god, this Thor's Helmet is about 30 light-years across.