| Omega Nebula (M17; NGC 6618) |
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A luminous nebula in the constellation Sagittarius, also known as the Horseshoe Nebula and the Swan Nebula. It is 4,800 light years away and 27 light years in diameter. It is a region of ionized hydrogen, excited by a group of at least five hot stars. A dark dust cloud lies on the western edge of the luminous region. See also: molecular cloud. |