Ursa Major

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Ursa major

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List of stars in Ursa major
Abbreviation:	UMa
Genitive:	Ursae Majoris
Symbology:	the Great Bear
Right ascension:	10.67 h
Declination:	+55.38°
Area:	1280 sq. deg. (3rd)
Main stars:	7, 20
Bayer/Flamsteed stars:	93
Stars known to have planets:	8
Bright stars:	6
Nearby stars:	12
Brightest star:	ε UMa (Alioth) (1.7124m)
Nearest star:	Lalande 21185 (8.29 ly)
Messier objects:	7
Meteor showers:	Alpha Ursa Majorids Leonids-Ursids
Bordering constellations:	Draco Camelopardalis Lynx Leo Minor Leo Coma Berenices Canes Venatici Boötes
Visible at latitudes between +90° and −30° Best visible at 21:00 (9 p.m.) during the month of April
The Big Dipper.

Ursa Major (pronounced /ˌɝsəˈmeɪdʒɚ/) is a constellation visible throughout the year in most of the northern hemisphere. Its name means Great Bear in Latin, and is associated with the legends of Callisto and Cynosura.

[edit] Notable features

The seven brightest stars, located in the Bear's hindquarters and tail, form the well-known Big Dipper asterism. (In United Kingdom and Ireland, this asterism is known as the Plough.) Except for Dubhe and Alkaid, the stars of the Big Dipper all have proper motions heading towards a common point in Sagittarius. A few other such stars have been identified, and together they are called the Ursa Major Moving Group.

In addition to the ursa major, another asterism comes from Arab culture, a series of three pairs of stars:

• ν and ξ Ursae Majoris, Alula Borealis and Australis, the "first leap";
• λ and μ Ursae Majoris, Tania Borealis and Australis, the "second leap";
• ι and κ Ursae Majoris, Talitha Borealis and Australis, the "third leap".

These stars are found along the southwest border of the constellation, the bear's toes.

Mizar, a star in the Big Dipper, forms the famous optical double star with Alcor.

The stars Merak (β Ursae Majoris) and Dubhe are known as the "pointer stars" because they are helpful for finding Polaris, also known as the North Star. By visually tracing a line from Merak through Dubhe and continuing, one's eye will land on Polaris, accurately indicating true north.

W Ursae Majoris is the prototype of a class of contact binary variable stars, and ranges between 7.75^m and 8.48^m.

47 Ursae Majoris has a planetary system with two confirmed planets, 2.54 times and 0.76 times the mass of Jupiter.

Several bright galaxies are found in Ursa Major, including the pair Messier 81 (one of the brightest galaxies in the sky) and Messier 82 above the bear's head, and Pinwheel Galaxy (M101), a beautiful spiral northwest of η Ursae Majoris. The other notable spiral galaxies Messier 108 and Messier 109 may also be found in this other constellation. Altogether, the constellation contains about 50 galaxies observable through amateur telescope. The bright planetary nebula Owl Nebula (M97), named for its appearance, can be found along the bottom of the bowl of the Big Dipper. Of note as a curiosity more than an interesting deep sky object is Messier 40, a double star that Messier nonetheless included in his catalogue.

The Hubble Deep Field is located to the northeast of δ Ursae Majoris.

Ursa Major was one of the 48 constellations listed by Ptolemy. It is one of the most widely-known constellations, having been mentioned by such poets as Homer, Spenser, Shakespeare, Tennyson and Bertrand Cantat. The Finnish epic Kalevala mentions it, and Vincent Van Gogh painted it upside down

[edit] Mythology

The constellation of Ursa Major has been seen by many distinct civilizations as a bear.^[1] In one sequence, together with the nearby Ursa Minor, it is associated with the myth of Callisto, in another the myth of Cynosura.

In another tale, Ursa Major was associated with the Hesperides. With Ursa Minor, Boötes, Draco, and Hercules it may have inspired the myth of the Apples of the Hesperides, one of The Twelve Labours of Hercules. In one myth, Zeus falls in love with a young woman. Hera, jealously turns the woman into a bear. The bear was then placed in front of the woman's son. The woman's son almost shot the bear, but Zeus swept it up into the sky, forming Ursa Major.

One of the few star groups mentioned in the Bible (Job 9:9; 38:32; Amos 5:8 — Orion and the Pleiades being others), Ursa Major was also pictured as a bear by both the Jewish people and most North American peoples. However, as bears do not have long tails, they considered Alioth, Mizar, and Alkaid to be either three cubs following their mother or three hunters. ("The Bear" was mistranslated as "Arcturus" in the Vulgate and the error persisted in the KJV. Later translations have corrected this.)

The Iroquois Native Americans also interpreted Alioth, Mizar, and Alkaid as three hunters pursuing the Great Bear. According to one version of their myth, the first hunter (Alioth) is carrying a bow and arrow to strike down the bear. The second hunter (Mizar) carries a large pot - the star Alcor - on his shoulder in which to cook the bear while the third hunter (Alkaid) hauls a pile of firewood to light a fire beneath the pot.

In Burmese, Pucwan Tārā (pronounced "bazun taja") is the name of a constellation comprising stars from the head and forelegs of Ursa Major; pucwan is a general term for prawn, shrimp, crab, lobster, etc.

[edit] Graphic visualisation

• Hevelius' work depicts an attempt to represent the constellation as a bear.
  

  

  The drawing Hevelius made of Ursa Major. The drawing is made as if being viewed from outside the celestial sphere.

• The constellation features prominently in van Gogh's painting "Starry Night Over the Rhone." Van Gogh placed it on the southern sky.

Please help improve this section by expanding it. Further information might be found on the talk page or at requests for expansion.

[edit] See also

• Ursa Minor

[edit] Citations

[edit] References

• Ian Ridpath and Wil Tirion (2007). Stars and Planets Guide, Collins, London. ISBN 978-0007251209. Princeton University Press, Princeton. ISBN 978-0691135564.

[edit] External links

• The Deep Photographic Guide to the Constellations: Ursa Major
• AAVSO: The Myths of Ursa Major
• The Origin of the Greek Constellations
• Star Tales – Ursa Major

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Ursa Major