Horsehead Nebula - Barnard 33
The Horsehead Nebula (also known as Barnard 33 in bright nebula IC 434) is a dark nebula in the constellation Orion.
The nebula is located just below (to the south of) Alnitak,
the star farthest left on Orion's Belt, and is part of the much largerOrion Molecular
Cloud Complex. 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 is similar to that of a horse's
head when viewed from Earth. The shape was first noticed in 1888 by Williamina
Fleming on
photographic plate B2312 taken at the Harvard College Observatory.
The red
glow 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