The Horsehead Nebula (also known as Barnard 33) is a dark nebula in the constellation Orion. The nebula is located just to the south of the star Alnitak, which is farthest east on Orion's Belt, and is part of the much larger Orion Molecular Cloud Complex. The nebula was first recorded in 1888 by Scottish astronomer Williamina Fleming on photographic plate B2312 taken at the Harvard College Observatory. The Horsehead Nebula is approximately 1500 light years from Earth. It is one of the most identifiable nebulae because of the shape of its swirling cloud of dark dust and gases, which bears some resemblance to a horse's head when viewed from Earth. The dark cloud of dust

Horsehead  434

3nm Halpha  - photo by gilad G

Processing Michael T.

and gas is a region in the Orion Molecular Cloud Complex where star formation is taking place. It is located in the constellation of Orion, which is prominent in the winter evening sky in the Northern Hemisphere and the summer evening sky in the Southern Hemisphere. This stellar nursery, as it is known, can contain over 100 known kinds of organic and inorganic gases as well as dust; some of the latter is made up of large and complex organic molecules.[citation needed] The red or pinkish glow originates from hydrogen gas predominantly behind the nebula, ionized by the nearby bright star Sigma Orionis