CONE NEBULA

The Cone Nebula is an H II region in the constellation of Monoceros.

The diffuse Cone Nebula, so named because of its apparent shape, lies in the southern part of NGC 2264, the northern part being the magnitude-3.9 Christmas Tree Cluster. It is in the northern part of Monoceros, just north of the midpoint of a line from Procyon to Betelgeuse.

The cone's shape comes from a dark absorption nebula consisting of cold molecular hydrogen and dust in front of a faint emission nebula containing hydrogen ionized by S Monocerotis, the brightest star of NGC 2264. The faint nebula is approximately seven light-years long (with an apparent length of 10 arcminutes), and is 2,700 light-years away from Earth.