The Lagoon Nebula is a massive star-forming region in Sagittarius. It is a cloud of mostly hydrogen gas. Ultraviolet radiation from the bright stars forming within the nebula causes the gas to glow. Dark globules of dust are visible throughout the nebula. The Lagoon Nebula is 5000 light-years away.
Image taken May 12th, 2010 from south of Tucson, AZ