Orion Molecular Cloud
The Horsehead Nebula is part of the Orion Molecular Cloud, located about 1,500 light-years away in one of the night sky's most recognizable constellations, Orion. The cloud also contains other well-known objects, such as the Great Orion Nebula (M42), the Flame Nebula, and Barnard's Loop. It is one of the nearest and most easily photographed regions in which massive stars are being formed.
This composite view shows exposures filtered to record emissions from hydrogen atoms and an array of nebulosities scattered throughout the giant Orion Molecular Cloud complex. The complex itself measures hundreds of light-years across.
A magnificent emission region, the Orion Nebula (or M42), is seen in the upper-right corner of the picture. Immediately to its left are a cluster of prominent bluish nebulae, which are sometimes called the Running Man. The Horsehead Nebula appears as a dark cloud, a small silhouette against the long red glow left of center. Alnitak is the easternmost star in Orion's belt and the brightest star to the left of the Horsehead. Below Alnitak is the Flame Nebula, with clouds of bright emission and dramatic dark dust lanes. Completing the trio of Orion's belt stars, bluish Alnilam and Mintaka form a line with Alnitak, extending to the upper left.