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Orion (constellation)
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Orion , often referred to as "The Hunter," is a prominent constellation – one of the largest, most conspicuous, and most recognizable in the night sky. Its name refers to Orion, a hunter in Greek mythology. Orion's brilliant stars are found on the celestial equator and are visible throughout the world.
Visualizations
Orion includes the prominent asterism known as the 'belt' of Orion: three bright stars in a row. Surrounding the belt at roughly similar distances are four bright stars, which are considered to represent the outline of the hunter's body.
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Orion , often referred to as "The Hunter," is a prominent constellation – one of the largest, most conspicuous, and most recognizable in the night sky. Its name refers to Orion, a hunter in Greek mythology. Orion's brilliant stars are found on the celestial equator and are visible throughout the world.
Visualizations
Orion includes the prominent asterism known as the 'belt' of Orion: three bright stars in a row. Surrounding the belt at roughly similar distances are four bright stars, which are considered to represent the outline of the hunter's body. Apparently descending from the 'belt' is a smaller line of three stars (one of which is in fact not a star but the Orion Nebula), known as the hunter's 'sword'.
See also the List of stars in Orion.
In artistic renderings, the surrounding constellations are sometimes related to Orion: he is depicted standing next to the river Eridanus with his two hunting dogs Canis Major and Canis Minor, fighting Taurus the bull. He is sometimes depicted hunting Lepus the hare.
There are alternative ways to visualize Orion. From the Southern Hemisphere, Orion is oriented differently, and the belt and sword are sometimes called the Saucepan, or Pot in Australia. Orion's Belt is called Drie Konings (Three Kings) or the Drie Susters (Three Sisters) by Afrikaans speakers in South Africa, are referred to as les Trois Rois (the Three Kings) in Daudet's Lettres de Mon Moulin (1866). The appellation Driekoningen (the Three Kings) is also often found in 17th- and 18th-century Dutch star charts and seaman's guides.
In the tropics (less than 8° from the equator) 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, however for most of Antarctica, the Sun is below the horizon even at midday, so stars (and thus Orion) are visible in at most twilight sky.
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Navigational aid
Orion is very useful as an aid to locating other stars. By extending the line of the Belt southeastward, Sirius (a CMa) can be found; northwestward, Aldebaran (a Tau). A line eastward across the two shoulders indicates the direction of Procyon (a CMi). A line from Rigel through Betelgeuse points to Castor and Pollux (a Gem and ß Gem). Additionally, Rigel is part of the Winter Circle. Sirius and Procyon, which may be located from Orion by tracing lines, also are points in both the Winter Triangle and the Circle.
Notable features
Stars
- Betelguese, known alternatively by its Bayer designation "Alpha Orionis," is a massive M-type red supergiant star nearing the end of its life. It is the second brightest star in the Orion constellation, but was mistakenly classified as the brightest because it is a semiregular variable star and was experiencing a tremendous increase in brightness at the time. It serves as the "right shoulder" of the hunter it represents (assuming that he is facing the observer), and is the twelfth brightest star in the night sky.
- Rigel, which is also known as "Beta Orionis," is a B-type blue supergiant that is the seventh brightest star in the night sky. Similar to Betelguese, Rigel is fusing heavy elements in its core and will pass its supergiant stage soon (on an astronomical timescale), either collapsing in the case of a supernova or shedding its outer layers and turning into a white dwarf. It serves as the left foot of Orion, the hunter.
- Bellatrix was designated "Gamma Orionis" by Johann Bayer, but is known collaquially as the "Amazon Star;" it is the twenty-second brightest star in the night sky. Bellatrix is considered a B-type blue giant, though it is too small to explode in a supernova. Bellatrix's luminosity is derived from its high temperature rather than its radius, a factor that defines Betelguese. Bellatrix serves as Orion's "left shoulder."
- Mintaka garnered the name "Delta Orionis" from Bayer, even though it is the faintest of the three stars in Orion's Belt. It is a multiple star system, composed of a large B-type blue giant and a more massive O-type white star. The Mintaka system constitutes an eclipsing binary variable star, where the eclipse of one star over the other creates a dip in brightness. Mintaka is the westernmost of the three stars that constitute Orion's Belt.
- Alnilam was named "Epsilon Orionis," a consequence of Bayer's wish to name the three stars in Orion's Belt (from north to south) in alphabetical order. Alnilam is a B-type blue supergiant, despite being nearly twice as far from the Sun as Mintaka and Alnitak, the other two belt stars. Alnilam is losing mass quickly, a consequence of its size; it is four million years old, approximately the same age as a hominid skeleton unearthed in Ethiopia in 2005.
- Alnitak was designated "Zeta Orionis" by Bayer, and is the easternmost star in Orion's Belt. It is a triple star some 800 light years distant, with the primary star being a hot blue supergiant and the brightest class O star in the night sky.
- Saiph was designated "Kappa Orionis" by Bayer, and serves as Orion's right foot. It is of a similar distance and size to Rigel, but appears much fainter, as its hot surface temperature (46,000°F or 26,000°C) causes it to emit most of its light in the ultraviolet region of the spectrum.
Of the lesser stars, Hatsya (or "Iota Orionis") forms the tip of Orion's sword, whilst Meissa (or "Lambda Orionis") forms the head. In common with many other bright stars, the names Betelgeuse, Rigel, Saiph, Alnitak, Mintaka, Alnilam, Hatsya and Meissa originate from the Arabic language.
Meteor showers
Around October 21 each year the famous Orionid meteor shower reaches its peak. Coming from the border to the constellation Gemini as much as 20 meteors per hour can be seen.
Deep sky objects
Hanging from Orion's belt is his sword, consisting of the multiple stars ?1 and ?2 Orionis, called Trapezium and the Orion Nebula (M42). This is a spectacular object which can be clearly identified with the naked eye as something other than a star; using binoculars, its swirling clouds of nascent stars, luminous gas, and dust can be observed.
Another famous nebula is IC 434, the Horsehead Nebula, near ? Orionis. It contains a dark dust cloud whose shape gives the nebula its name.
Besides these nebulae, surveying Orion with a small telescope will reveal a wealth of interesting deep sky objects, including M43, M78, as well as multiple stars including Iota Orionis and Sigma Orionis. A larger telescope may reveal objects such as Barnard's Loop, the Flame Nebula (NGC 2024), as well as fainter and tighter multiple stars and nebulae.
All of these nebulae are part of the larger Orion Molecular Cloud Complex which is located approximately 1,500 light-years away and is hundreds of light-years across. It is one of the most intense regions of stellar formation visible in our galaxy.
Cultural significance
The current configuration of stars now known as the constellation of Orion roughly formed about 1.5 million years ago, as stars move relatively slowly from the perspective of Earth. Orion will remain recognisable 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.
Because they are so bright and distinctive, the pattern of stars that forms Orion was recognized as a coherent constellation by many ancient civilizations, though with different representations and mythologies.
Ancient Near East
It is possible that the naming of the constellation Orion preceded the Greek mythology surrounding that character. It has been suggested that Orion is named from the Akkadian Uru-anna, the light of heaven, the name then passing into Greek mythology. As such, the myth surrounding Orion may derive simply from the relative positions of the constellations around it in the sky.
The ancient Sumerians saw this star pattern as forming part of an image of a shepherd (sometimes in a chariot) with his sheep and in some versions a shepherd's crook, while in China, Orion was one of the 28 lunar mansions Sieu (Xiu). Known as Shen, literally meaning "three", it is believed to be named so for the three stars located in Orion's belt. (See Chinese constellations)
The Bible mentions Orion three times: Job 9:9 ("He is the maker of the Bear and Orion"), Job 38:31 ("Can you loosen Orion`s belt?"), and Amos 5:8 ("He who made the Pleiades and Orion").
The Jewish biblical commentators say that Orion emits heat preventing the winter from getting too cold.
In ancient Aram, the constellation was known as Nephila, Orion's descendants were known as Nephilim.
Egyptian
The stars were associated with Osiris, the god of death and underworld, by the ancient Egyptians.
It has also been identified with the historic figure Unas (last Pharaoh of Ninth Dynasty) who became great by eating the flesh of his mortal enemies and then slaying and devouring the gods themselves. Those gods that were old and worn out were used as fuel for Unas's fire. After devouring the gods and absorbing their spirits and powers, Unas journeys through the day and night sky to become the star Sabu, or Orion. This is arguable, however, because many Egyptian texts would allude to Orion as being the god Osiris.
Greek and Roman
Orion's current name derives from Greek mythology, in which Orion was a gigantic hunter of primordial times. Some of these myths relate to the constellation; one story tells that Orion was killed by a giant scorpion; the gods raised him and the Scorpion to the skies, as Scorpio/Scorpius. Yet other stories say Orion was chasing the Pleiades.
In some depictions, Orion appears to be composed of three bodies, having three arms , two divergent legs, and a small central one, as well as the three bodies being bound at the waist. As such, together with other features of the area in the Zodiac sign of Gemini (i.e. the Milky Way, the deserted area now considered as the constellations Camelopardalis and Lynx, and the constellations Gemini, Auriga, and Canis Major), this may be the origin of the myth of the cattle of Geryon, which forms one of The Twelve Labours of Heracles.
The constellation is mentioned in Horace's Odes, Homer's Odyssey and Iliad, and Virgil's Aeneid.
Scandinavia
In pre-Christian Scandinavia, "Orion's belt" was known as Frigg's Distaff (Friggerock) or Freyja's distaff.
In Finnish mythology the constellation of Orion is called the scythe of Väinämöinen. The term most likely comes from the fact it can be seen in the sky in early autumn in the Northern Hemisphere, the time of harvesting crops.
Indian
In Indian mythology, the constellation is known as 'Vyudh', which also means "The Hunter". It is also known as Kalpurush (the Destroyer). The Rig Veda refers it to as Mriga (The Animal or Deer).
Chinese
The Chinese character ? (pinyin shen) originally meant the constellation Orion ; its Shang dynasty version, over three millennia old, contains at the top a representation of the three stars of Orion's belt atop a man's head (the bottom portion representing the sound of the word was added later).
Native American
The Yokut Native American tribe of the California Central Valley saw the three bright stars as the foot prints of the god of the flea people. According to legend, when his five wives became itchy and ran away, three times the god of the flea people jumped into the sky to look for them. When his footprints cannot be seen (stars drop below the horizon winter months) the flea people grow afraid and go into hiding (i.e. dormant). This helped explain to the tribal people why they couldn't count on those stars for guides in winter months, and why there were no fleas about.
The Seri people of northwestern Mexico call the three stars in the belt of this constellation Hapj (a name denoting a hunter) which consists of three stars: Hap (mule deer), Haamoja (pronghorn), and Mojet (bighorn sheep). Hap is in the middle and has been shot by the hunter; its blood has dripped onto Tiburón Island.
The Aztecs called the belt and sword of Orion the Fire Drill. Its appearance over the horizon served as the signal of the start of the New Fire ceremony.
Australian aboriginal
Orion is also important in Australian Aboriginal Astronomy. For example, the Yolngu people of Arnhem Land say that the constellation of Orion, which they call Julpan, is a canoe. They tell the story of two brothers who went fishing, and caught and ate a fish that was forbidden under their law. Seeing this, the Sun sent a waterspout that carried the two brothers and their canoe up into the sky where they became the Orion constellation.
Contemporary symbolism
The imagery of the belt and sword has found its way into popular western culture, for example in the form of the shoulder insignia of the 27th Infantry Division of the United States Army during both World Wars, probably owing to a pun on the name of the division's first commander, Major General John F. O'Ryan.
The defunct film distribution company Orion Pictures used the constellation as its logo.
See also
External links
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