The Flame Nebula (NGC 2024) is in the Constellation Orion and it is about 900 to 1,500 light years away. The bright star Alnitak, the easternmost star in the Belt of Orion, shines energetic ultraviolet light into the Flame and this knocks electrons away from the great clouds of hydrogen gas that reside there. Much of the glow results when the electrons and ionized hydrogen recombine. Additional dark gas and dust lies in front of the bright part of the nebula and this is what causes the dark network that appears in the center of the glowing gas. The Flame Nebula is part of the Orion Molecular Cloud Complex, a star-forming region that includes the famous Horsehead Nebula.
Dreyer's description from the New General Catalog(NGC): "Remarkable! Irregular, bright, very, very large, black lane included."
George Normandin, KAS
April 12th, 2008