The constellation Orion is often referred to as "The Hunter." It is a prominent constellation located on the celestial equator and visible to the whole world. It is one of the largest, most eye catching, and most familiar in the night sky. Its name refers to Orion, a hunter in Greek mythology.
Orion includes the famous asterism known as the Belt of Orion, which are three bright stars in a row. Surrounding the belt at about similar distances are four bright stars, which are considered to represent the outline of the hunter's body. It appears to be descending from the belt as a smaller line of three stars. One of these stars which is in fact not a star but the Orion Nebula, known as the hunter's 'sword'.
Orion is currently located on the celestial equator, but it will not always be so located there. Orion lies well south of the ecliptic, and only happens to lie on the celestial equator because the point on the ecliptic that corresponds to the June solstice is close to the border of Gemini and Taurus, to the north of Orion. Precession will eventually carry Orion further south, and by 14,000 AD Orion will be far enough south that it is invisible from the latitude of Britain.
Further in the future, Orion's stars will gradually move away from the constellation due to proper motion. However, Orion's brightest stars all lie at a respectable distance from Earth. Orion will still be recognizable long after most other constellations composed of nearby stars have distorted into new configurations, with the exception of a few of its stars eventually exploding as supernovae. For example, Betelgeuse, the "right shoulder", is so large and old enough that it may explode and disappear within a few thousand years.
From the Southern Hemisphere, Orion is tilting differently. Orion's Belt is called Drie Konings (Three Kings) or the Drie Susters (Three Sisters) by Afrikaans speakers in South Africa. The designation Driekoningen (the Three Kings) is also often found in 17th- and 18th-century Dutch star charts and seaman's guides. The same three stars are known in Latin America as "The Three Marys."
In the tropics the constellation transits in the zenith which is best seen in Nov-Feb each year. In the northern hemisphere it is a winter constellation and then it is summer in the southern. However, in Antarctica it is best seen in winter as in summer the Sun does not set and therefore no stars are visible. In winter (May-July), Orion is in the 'daytime' sky, but for most of Antarctica, the Sun is below the horizon even at midday, so stars, including Orion are visible mostly in twilight sky.
Orion roughly formed about 1.5 million years ago, as stars move slowly from the perspective of Earth. Orion will remain recognizable in the night sky for the next 1 to 2 million years, making it one of the longest observable constellations, parallel to the rise of human civilization.
Orion was a giant huntsman of Greek mythology whom Zeus placed among the stars as the constellation of Orion. The most important recorded episodes are his birth somewhere in Boeotia, his visit to Chios where he met Merope and was blinded by her father, Oenopion, the recovery of his sight at Lemnos, his hunting with Artemis on Crete, his death by the blow of Artemis or of the giant scorpion which became Scorpio, and his elevation to the heavens. Orion served several roles in ancient Greek culture. Orion was venerated as a hero, in the Greek sense, in the region of Boeotia; and Orion was responsible for the present shape of the Straits of Sicily.
The closest of the major stars in Orion is Saiph. Saiph is located down by the left foot of the hunter. It is 720 light years away and located at the B0 spectral class. Betelgeuse is about 450 light years distant and located at the M0 spectral class. If Betelgeuse was located where the Sun is, Earth, Mars and possibly Jupiter would be inside the star. Betelgeuse will eventually explode as a nova or supernova. Betelgeuse is about 400 light years away and a supernova would have to be within 100 light years to be a serious threat. Although we think of Betelgeuse as the left shoulder of Orion, the name means something closer to armpit.
Bellatrix is 240 light years away and located at the B2 spectral class, close enough that it seems unlikely to have been formed from the same cloud of dust that created most of the Orion stars. Bellatrix is probably the only one of Orion's major stars that won't explode at some point in time. It is found at the right shoulder of Orion. Rigel is actually the brightest star in Orion despite the designation "Beta Orionis". In fact, Rigel is probably a dying star having exhausted its supply of hydrogen and is now burning helium into oxygen and carbon.Rigel is also located at the B8 spectral class.
The stars of Orion's belt are, from left to right, Alnitak, Alnilam and Mintaka. The three stars are similar, and they are located at the B0 speactral class. They are all blue-white giants that will eventually supernova. They appear to be nearly equal in magnitude so the essentially brightest would have to be the one furthest away. That would be Alnilam around 1300 lights years distant. Alnitak is 870 light years away and Mintaka is 915 light years distant.
Below is a chart of Orion's Star Coordinates
This is a picture of the Constellation Orion
Graphic:,Orion Constellation.
Betelgeuse is a semi regular variable star located approximately 450 light-years from the Earth. It is the second brightest star in the constellation Orion, and the ninth brightest star in the night sky. The star is a vertex of the Winter Triangle and center of the Winter Hexagon. Betelgeuse is a red supergiant, and one of the largest and most luminous stars know. Astronomers believe Betelgeuse is only a few million years old, but has evolved rapidly because of its high mass. Some astronomers believe it may become a supernova within a timeframe where it could be observable by human civilization. Betelgeuse is a type M0 class, under the spectral class sense.
Picture of Betelgeuse
Graphic:,Betelguse.
HR Diagram of Betelguese
The Orion Arm is a minor spiral arm of the Milky Way galaxy some 3,500 light years across and approximately 10,000 light years in length. The Solar System and Earth are within the Orion Arm. It is also referred to as the Local Arm, the Local Spur or the Orion Spur. The Orion Arm is named for its proximity to the stars in the Orion constellation. It is located between the Sagittarius Arm and the Perseus Arm, two of the four major arms of the Milky Way. The Orion Arm contains fifteen clusters of stars, seven Nebulas, and three different other stars. Its celestial coordinates are located between M6 and M97. The Orion Arm is known as a galaxy is a spiral galaxy.
This is a picture of Orion's
Graphic:,Orion Arm.
The Orion Nebula located at the celestial coordinates M42 and M43. It is a diffuse nebula located south of Orion's Belt. It is one of the brightest nebulae, and is visible to the naked eye in the night sky. M42 is located at a distance of 20 light years and is the closest region of massive star formation to Earth. This nebula is referred as the Great Nebula. This nebula is an emission nebula meaning that it is clouds of high temperature gas. Compared to other nebulae of the galaxy, Orion Nebula is a relatively luminous nebula with a visual magnitude of 4. The four bright stars in the center, the trapezium, have actually blown out a hole in the nebula that lets us see inside. The trapezium is actually a multiple star system designated as Theta Orion.
This is a picture of Orion Nebula
Graphic:,Orion Nebula.
The stars of Orion's belt are, from left to right, Alnitak, Alnilam and Mintaka. The three stars are similar. They are all blue-white giants that will eventually supernova. They appear to be nearly equal in magnitude so the intrinsically brightest would have to be the one furthest away. They are located at the spectral class B0. That would be Alnilam around 1300 lights years distant. Alnitak is 870 light years away and Mintaka is 915 light years distant. All of these stars were formed from the same interstellar cloud that also is the source of the Great Nebula in Orion.
This is a picture of Orion's Belt
Graphic:,Orion Nebula.
HR Diagram of Orion's Belt
1: Lloyd Motz, Carol Nathanson. The Constellations. New York: Doubleday, 1988. This big contained a description on Orion. It told me about the different stars in the constellation. This book was very helpful in getting information for the overview of this html file.
2: Kohlmiller, Paul. "The Stars of Orion." SJAA Ephemeris April 2005 (2004): n. pag. Web. 1 Dec 2009.
"Astronomy: Orion." DOMEX E-DATA PVT. LTD.,, Web.