Orion, sometimes subtitled The Hunter, is a prominent constellation located on the celestial equator and visible throughout the world. It is one of the most conspicuous, and most recognisable constellations in the night sky. Its name refers to Orion, a hunter in Greek mythology.
| Constellation | |
 List of stars in Orion |
|
| Abbreviation | Ori |
|---|---|
| Genitive | Orionis |
| Pronunciation | /ɒˈraɪ.ən/ |
| Symbolism | Orion, the Hunter |
| Right ascension | 5 h |
| Declination | +5° |
| Quadrant | NQ1 |
| Area | 594 sq. deg. (26th) |
| Main stars | 7 |
| Bayer/Flamsteed stars |
81 |
| Stars with planets | 7 |
| Stars brighter than 3.00m | 8 |
| Stars within 10.00 pc (32.62 ly) | 8 |
| Brightest star | Rigel (β Ori) (0.12m) |
| Nearest star | GJ 3379 (17.51 ly, 5.37 pc) |
| Messier objects | 3 |
| Meteor showers | Orionids Chi Orionids |
| Bordering constellations |
Gemini Taurus Eridanus Lepus Monoceros |
Visible at latitudes between +85° and −75°. Best visible at 21:00 (9 p.m.) during the month of January.  | |
Visualisations
See also: List of stars in Orion
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. Descending from the 'belt' is a smaller line of three stars (the middle of which is in fact not a star but the Orion Nebula), known as the hunter's 'sword'.
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. He also sometimes is depicted to have a lion in his hand.
There are alternative ways to visualise Orion. From the Southern Hemisphere, Orion is oriented south-upward, and the belt and sword are sometimes called the saucepan or pot in Australia and New Zealand. Orion's Belt is called Drie Konings (Three Kings) or the Drie Susters (Three Sisters) by Afrikaans speakers in South Africa and 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. The same three stars are known in Spain and Latin America as "Orión".
Visibility
Orion can be easily seen in the night sky from November to February of each year - late fall to winter in the Northern Hemisphere, late spring to summer in the Southern Hemisphere. In the tropics (less than about 8° from the equator) the constellation transits at the zenith.In the period May–July (summer in the Northern Hemisphere, winter in the Southern Hemisphere) Orion is in the daytime sky and thus not visible at most latitudes. However for much of Antarctica in the Southern Hemisphere's winter months, the Sun is below the horizon even at midday. Stars (and thus Orion) are then visible at twilight for a few hours around local noon, low in the North. At the same time of day at the South Pole itself (Amundsen-Scott South Pole Station), Rigel is only 8° above the horizon and the Belt sweeps just along it. In the Southern Hemisphere's summer months, when Orion is normally visible in the night sky, the constellation is actually not visible in Antarctica because the sun does not set at that time of year south of the Antarctic Circle.
In countries close to the equator (e.g. Kenya, Indonesia, Colombia, Ecuador) Orion appears overhead in December around midnight and in the February evening sky.
Notable features
Stars
See also: list of stars in Orion
- Betelgeuse, known alternatively by its Bayer designation Alpha Orionis, is a massive M-type red supergiant star nearing the end of its life. When it explodes it will even be visible during the day. It is the second brightest star in Orion, and is a semiregular variable star. It serves as the "right shoulder" of the hunter it represents (assuming that he is facing the observer), and is the eighth brightest star in the night sky.
- Rigel, which is also known as Beta Orionis, is a B-type blue supergiant that is the sixth brightest star in the night sky. Similar to Betelgeuse, 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 colloquially 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 Betelgeuse. 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 of 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, its luminosity makes it nearly equal in magnitude. Alnilam is losing mass quickly, a consequence of its size; it is approximately four million years old.
- 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.
| Proper Name |
Solar Radii | Apparent Magnitude |
~Distance (L Yrs) |
|---|---|---|---|
| Betelgeuse | 667 | 0.43 | 643 |
| Rigel | 78 | 0.18 | 772 |
| Bellatrix | 7.0 | 1.62 | 243 |
| Mintaka | ? | 2.23 (3.2/3.3) / 6.85 / 14.0 | 900 |
| Alnilam | 26 | 1.68 | 1359 |
| Alnitak | ? | 1.70/~4/4.21 | 800 |
| Saiph | 11 | 2.06 | 724 |
Belt
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| Orion Constellation Map |
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| Closeup Image of Orion Belt |
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The Belt of Orion
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Zeta and Epsilon Orionis of Orion’s Belt and the Flame Nebula (centre), with the Horsehead Nebula below
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Orion and a total lunar eclipse as viewed from the surface of the earth
Meteor showers
Around October 20 each year the Orionid meteor shower reaches its peak. Coming from the border with the constellation Gemini as many as 20 meteors per hour can be seen.
Deep-sky objects
Hanging from Orion's belt is his sword, consisting of the multiple stars θ1 and θ2 Orionis, called the 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 clouds of nascent stars, luminous gas, and dust can be observed.
Another famous nebula is IC 434, the Horsehead Nebula, near ζ 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 and 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
Mediterranean
Ancient Near East
The Babylonian star catalogues of the Late Bronze Age name Orion MULSIPA.ZI.AN.NA, "The Heavenly Shepherd" or "True Shepherd of Anu" - Anu being the chief god of the heavenly realms. The Babylonian constellation was sacred to Papshukal and Ninshubur, both minor gods fulfilling the role of 'messenger to the gods'. Papshukal was closely associated with the figure of a walking bird on Babylonian boundary stones, and on the star map the figure of the Rooster was located below and behind the figure of the True Shepherd.
The stars of Orion were associated with Osiris, the sun-god of rebirth and afterlife, by the ancient Egyptians.
Orion has also been identified with the Egyptian Pharaoh of the Fifth Dynasty called Unas who, according to the Pyramid Texts, became great by eating the flesh of his mortal enemies and then slaying and devouring the gods themselves. This was based on a belief in contiguous magic whereby consuming the flesh of great people would bring inheritance of their power. 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. The Pyramid Texts also show that the dead Pharaoh was identified with the god Osiris, whose form in the stars was often said to be the constellation Orion.
The Bible mentions Orion three times, naming it "Kesil" (כסיל, literally - fool. Though, this name perhaps is etymologically connected with "Kislev", the name for the ninth month of the Hebrew calendar (i.e. November-December), which, in turn, may derive from the Hebrew root K-S-L as in the words "kesel, kisla" (כֵּסֶל ,כִּסְלָה, hope, positiveness), i.e. hope for winter rains.): 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"). In ancient Aram, the constellation was known as Nephîlā′, the Nephilim may have been Orion's descendants.
Greco-Roman antiquity
Main article: Orion (mythology)
The constellation is mentioned in Horace's Odes, Homer's Odyssey (Book 5, line 283) and Iliad, and Virgil's Aeneid (Book 1, line 535)
Middle East
In medieval Muslim astronomy, Orion was known as al-jabbar "the giant".[citation needed]
In ancient Egypt, the constellation of Orion was known to represent Osiris, who, after being killed by his evil brother Set, was revived by his wife Isis to live immortal among the stars.
Asian antiquity
In China, Orion was one of the 28 lunar mansions Sieu (Xiu) （宿）. Known as Shen （參）, literally meaning "three", it is believed to be named so for the three stars located in Orion's belt. (See Chinese constellations)
The Chinese character 參 (pinyin shēn) originally meant the constellation Orion (Chinese: 參宿; pinyin: shēnxiù); 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).
The Rig Veda refers to the Orion Constellation as Mriga (The Deer).
The Malay called Orion' Belt Bintang Tiga Beradik (the "Three Brother Star").
European folklore
In Scandinavian tradition, "Orion's belt" was known as Frigg's Distaff (Friggerock) or Freyja's distaff.
The Finns call the Orion's belt and the stars below it as Väinämöisen viikate (Väinämöinen's scythe).[citation needed]
New World
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 same three stars are known in Latin America as "The Three Marys."
The Ojibwa (Chippewa) Native Americans call this constellation Kabibona'kan, the Winter Maker, as its presence in the night sky heralds winter.
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.
In fiction
In J.R.R. Tolkien's mythology surrounding Middle-Earth, Orion is known as Menelvagor, which is Sindarin for "The Swordsman in the Sky."
In J.K. Rowling's Harry Potter series, one of the main Death Eater characters, Bellatrix Lestrange, is named after the gamma star in Orion.
Future
Orion is located on the celestial equator, but it will not always be so located due to the effects of precession of the Earth's axis. Orion lies well south of the ecliptic, and it 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 AD 14,000 Orion will be far enough south that it will become invisible from the latitude of Great 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 large distance from the Earth on an astronomical scale—much farther away than Sirius, for example. Orion will still be recognizable long after most of the other constellations—composed of relatively nearby stars—have distorted into new configurations, with the exception of a few of its stars eventually exploding as supernovae, for example Betelgeuse, which is predicted to explode sometime in the next million years.
From Wikipedia, the free encyclopedia.
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