Orion's Belt and Sword, March 18, 2009. The central region of the winter constellaton Orion is easily recognized by the three bright belt stars. The three stars have the names Alnitak, Alnilam and Mintaka, or to use their Bayer names, Zeta, Epsilon and Delta Orionis. In my photograph above, the constellation is turned on its side compared to how it's usually viewed in the Northern Hemisphere, and Alnitak is the lower most of the belt stars. This is a hot, blue supergiant star that is shining energetic ultraviolet light into massive clouds of hydrogen gas causing them to glow. The bright Flame Nebula (NGC 2024) is to the left of Alnitak, and the reddish Horsehead Nebula (IC 434) is to the right. The shape of the horsehead is caused by an enormous dust cloud in front of the glowing hydrogen. Here is a detail of the Flame and Horsehead Nebulae.
One the right side of the photograph is the Great Orion Nebula (M42). This part of the constellation is sometimes called Orion's Sword. This cloud of hydrogen and dust is about 24 light years across, and it's one of the night sky's most beautiful objects to observe. Here is a detail of the Great Orion Nebula.
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