Horsehead nebula

Horsehead Nebula

(Credit: N. Sharp, NOAO/AURA/NSF)

About 1500 ly from Earth, the Horsehead Nebula is part of a large dark nebula (known as Barnard 33 or B33) which happens to silhouette against the bright reddish emission nebula IC 434, outlining the head of a horse. Bright spots on the Horsehead Nebula's base are young stars just in the process of forming.

Credit: NASA, NOAO, ESA and The Hubble Heritage Team (STScI/AURA)

Image above shows a close-up of the Horsehead Nebula, taken by the HST. The bright area at the top left of the Horsehead is a young star still embedded in its nursery of gas and dust. The Horsehead Nebula lies just south of the bright star Alnitak or Zeta Orionis, which is easily visible to the unaided eye as the left-most (or appear right-most for an observer at the southern hemisphere) star in the line of three that form Orion's Belt. Amateur astronomers often use the Horsehead as a test of their observing skills; it is known as one of the difficult objects to see visually in an amateur-sized telescope. It is also a popular target to test one's astrophotographic skill where hours of exposures are required to produce a good horse head image.