The Horsehead Nebula (also known as Barnard 33 in bright nebula IC 434)
is a dark nebula in the Orion constellation. The nebula is located just
below Alnitak, the star furthest left on Orion's Belt, and is part of
the much larger Orion Molecular Cloud Complex. It is approximately 1,500
light years from Earth, and is approximately 3.5 light years wide.

One of the most identifiable nebulae in the sky, it is part of a swirling
cloud of dark dust and gases, shaped like a horse's head (hence its name),
but some people also believe it looks like a lion and it's mane Also known
as Barnard 33, the unusual shape was first discovered in 1888 by Williamina
Fleming on photographic plate B2312 taken at the Harvard College Observatory.

The red glow (the bright area in this monochrome image)originates from
hydrogen gas predominantly behind the nebula,ionized by the nearby bright
star Sigma Orionis. The darkness of the Horsehead is caused mostly by thick
dust, although the lower part of the Horsehead's neck casts a shadow to the left.
Streams of gas leaving the nebula are funneled by a strong magnetic field.
Bright spots in the Horsehead Nebula's base are young stars just in the
process of forming. (source: Wikipedia)