Credit & Copyright: Nigel Sharp (NOAO), KPNO, AURA, NSF
Explanation: One of the most identifiable nebulae in the sky, the Horsehead Nebula in Orion,
is part of a large, dark, molecular cloud. Also
known as Barnard 33, the
unusual shape was first discovered on a photographic
plate in the late 1800s. 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.
Light takes about 1,500 years to reach us from the Horsehead Nebula. The above image was
taken with the 0.9-meter
telescope at Kitt Peak National
Observatory.
