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.
A blue
reflection nebula dubbed
NGC 2023 surrounds the bright star at the lower left.
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 1500 years to reach us from the
Horsehead Nebula.
The above image
was taken earlier this month with a 0.6-meter telescope at the
Mt. Lemmon SkyCenter in
Arizona,
USA.
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