Orion (constellation)

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Orion
Abbreviation	Ori
Genitive	Orionis
Meaning in English	the Great Hunter
Right ascension	5 h
Declination	5°
Visible to latitude	Between 85° and −75°
Best visible	January
Area  - Total	Ranked 26th 594 sq. deg.
Number of stars with apparent magnitude < 3	6
Brightest star  - Apparent magnitude	Rigel (β Orionis) 0.12
Meteor showers	Orionids Chi Orionids
Bordering constellations	Gemini Taurus Eridanus Lepus Monoceros

Orion, the Hunter, is a prominent constellation, perhaps the best-known in the sky. Its brilliant stars, on the celestial equator and visible throughout the world, make this constellation universally recognized.

Orion is standing next to the river Eridanus with his two hunting dogs Canis Major and Canis Minor, fighting Taurus the bull. Other prey of his, such as Lepus the hare, can be found nearby.

Notable features

The constellation is extremely rich in bright stars and in deep-sky objects. Here are some of its stars:

• Heka is Orion's head.
• Betelgeuse (α), at its right shoulder, is a red star, larger than the orbit of Venus. The title of α-star was falsely awarded to this star; it should have been given to Rigel instead, which is somewhat brighter. Betelgeuse is actually a sextuple star, but its companions are too small to be easily seen. It forms a point of the Winter Triangle.
• Bellatrix (γ), "warrior woman," is at Orion's left shoulder.
• Alnitak, Alnilam and Mintaka (ζ, ε and δ) make up the asterism known as Orion's Belt: three bright stars in a row; even from these alone one can recognize Orion.
• Saiph is at Orion's right knee.
• Rigel (β), at the constellation's left knee, is a large white star, among the brightest in the sky. It has three companions, also difficult to see.
• Hatsya (ι) is at the tip of Orion's sword.

Guide to Orion

The major stars of Orion are all very similar in age and physical characteristics, suggesting that they may have a common origin. Betelgeuse is the single exception to this.

Orion is very useful in locating other stars. By extending the line of the Belt southwestward, Sirius (α Canis Majoris) can be found; northeastward, Aldebaran, α Tauri. A line eastward across the two shoulders indicates the direction of Procyon, α Canis Minoris. A line from Rigel through Betelgeuse points to Castor and Pollux, α and β Geminorum.

Notable deep sky objects

Hanging from Orion's belt is his sword, consisting of the multiple stars θ1 and θ2 Orionis, called Trapezium and the nearby Orion Nebula (M42). This is a spectacular object which can clearly identified with the naked eye as being something other than a star; using a pair of binoculars, its swirling 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.

History

Great Nebula Orion

Being such a brilliant pattern of stars, Orion was recognized by many ancient civilizations, though with different images.

The ancient Sumerians saw this star pattern as a sheep. The name Betelgeuse literally means "the armpit"; in the case of the Sumerians it meant "the armpit of the sheep".

In ancient China, Orion is one of the 28 zodiac Xiu (宿). Known as Shen (參), literally meaning "three", it is probably so named because of the three stars on Orion's belt. See Chinese constellation.

The stars were considered to be a tribute to the god of light, Osiris by the ancient Egyptians.

The "belt and sword" of Orion are frequently referred to in ancient and modern literature, and even found recognition as the shoulder insignia of the 27th Infantry Division of the United States Army during both World Wars, probably because the division's first commander was Major General John F. O'Ryan.

Mythology

Main article: Orion (mythology)

It is not very surprising to see such a prominent constellation to have more than one version of a story surrounding it in Greek mythology.

In one version, Orion claims himself to be the greatest hunter in the world. This is heard by Hera, the wife of Zeus, and she decided to send a scorpion after Orion. Orion is stung to death by the scorpion. Zeus felt sorry for Orion and put him onto the sky. The scorpion is also taken up to the sky, becoming the constellation Scorpius. It is an interesting fact that when one of the two constellations rises from the horizon, the other would have already set. So the two rivals can never see each other again.

It may be that the naming of the constellation precedes the mythology in this case. it has been suggested that Orion is named from the Akkadian Uru-anna, the light of heaven, the name then passing into Greek mythology.

The constellation is mentioned in Horace's Odes, Homer's Odyssey and Iliad, and Virgil's Aeneid.

The constellation of Orion also appears in Milton's Paradise Lost, and Tennyson's Locksley Hall, "Great Orion sloping slowly to the west".

Stars in the Orion constellation

See also

• Orvandil

External link

• Map of Orion

de:Orion (Sternbild) es:Orión (constelación) eo:Oriono fr:Orion (constellation) it:Orion (astronomia) nl:Orion (sterrenbeeld) ja:オリオン座 pl:Orion (gwiazdozbiór) pt:Orion fi:Orion (tähdistö) sv:Orion (stjärnbild) zh-cn:猎户座 zh-tw:獵戶座