The Constellation Orion


Orion - The Hunter

Orion is one of the best known and most easily recognized constellations in the night sky. The constellation forms the outline of a hunter. The red star at the top left of the constellation (representing the hunter's shoulder) is Betelgeuse, which is a red giant star (spectral type M2). If Betelgeuse was placed in our solar system where the Sun is located, the red giant is so large it would extend out to the orbit of Mars. Needless to say, if that were the case, then the planet earth would be toast. The star at the bottom right of the constellation is Rigel, (representing the hunter's leg), which is a spectral type B8 star. The three stars in the middle forming the belt of Orion are, from left to right, Zeta Orionis (Alnitak), Epsilon Orionis (Alnilam), and Delta Orionis (Mintaka).

Orion boasts a number of interesting deep sky objects. There are three Messier objects in Orion - - M42, M78, and M43. M42 is the Orion Nebula, and can be seen in this photo as the red area visible in the sword of Orion. The Horsehead Nebula and the Flame Nebula are both near Zeta Orionis. Additional nebulae can also be found in the surrounding area, and would have been visible if this had been a long exposure photograph.

The faint red patch to the left of Betelgeuse is the Rosette Nebula in Monoceros. The Witchhead Nebula is just to the right of Rigel, in the constellation Eridanus, but is too faint to show up in this photo.

A portion of the constellation Taurus is visible in the top right corner of this photo. The bright star at the upper right corner of the photo is Aldebaran, which is the brightest star in Taurus. The V-shaped arrangement of stars in Taurus extending from Aldebaran down to Gamma Tauri and then up to Epsilon Tauri is known as the Hyades. These stars form the head of the bull in Taurus. The Hyades is one of the closest star clusters. Aldebaran is not a true member of the star cluster, and is significantly closer to us than the stars that are members of the cluster. The stars in the Hyades are moving away from us, and in 50 million years the cluster will have receded so far and will have become so dim that a telescope will be required to detect the cluster, which by then will only be about 20 arc-minutes in diameter. The color-magnitude diagram of the Hyades is virtually identical to the Praesepe Star Cluster, and both star clusters have very nearly the same space motion and velocity.

This photo was taken using a Nikon F2 camera with a 35mm lens, and was a short exposure. The length of the exposure was kept short in order to avoid star trails, because the camera was mounted on a fixed tripod.

Constellation: Orion
March 30, 2004
Photo by Sid Leach
Kitt Peak, Arizona

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