... Barnards Loop around the Horsehead Nebula . ... Although hard to make out above, the famous Horsehead Nebula is the slight dark indentation in the bright streak just to the left of the image center. Glowing like an emission nebula, the origin of the bubble, known as Barnard's Loop, is currently unknown. ... Orion Nebula: The Hubble View . ... But the comet's greenish glow, familiar to earthbound skygazers, is replaced by false colors in this premier view from the orbiting Swift satellite. ...