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Ursa Major
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===Asterisms=== [[File:Ursa Major and Polaris.svg|thumb|left|Ursa Major and Polaris with names of bright stars in the Big Dipper]] [[Image:UrsaMajorCC.jpg|thumb|upright=.8|The constellation Ursa Major as it can be seen by the unaided eye]] The outline of the seven bright stars of Ursa Major form the [[Asterism (astronomy)|asterism]] known as the "''[[Big Dipper]]''" in the United States and Canada, while in the United Kingdom it is called the ''Plough''{{Hairspace}}<ref>{{cite book|author=Reader's Digest Association|title=Planet Earth and the Universe|url=https://books.google.com/books?id=Q5-RAAAACAAJ|date=August 2005|publisher=Reader's Digest Association, Limited|isbn=978-0-276-42715-2|access-date=2016-11-07|archive-date=2021-04-15|archive-url=https://web.archive.org/web/20210415002500/https://books.google.com/books?id=Q5-RAAAACAAJ|url-status=live}}</ref> or (historically) ''Charles' Wain''.<ref name="Wikidic">{{cite web |title=Charles' Wain |url=https://en.wiktionary.org/wiki/Charles%27_Wain |access-date=23 November 2017 |archive-date=1 December 2017 |archive-url=https://web.archive.org/web/20171201044025/https://en.wiktionary.org/wiki/Charles%27_Wain |url-status=live}}</ref> Six of the seven stars are of [[second magnitude star|second magnitude]] or higher, and it forms one of the best-known patterns in the sky.<ref>{{cite book|author=André G. Bordeleau|title=Flags of the Night Sky: When Astronomy Meets National Pride|url=https://books.google.com/books?id=NSu5BAAAQBAJ&pg=PA131|date=22 October 2013|publisher=Springer Science & Business Media|isbn=978-1-4614-0929-8|pages=131–|access-date=7 June 2019|archive-date=15 April 2021|archive-url=https://web.archive.org/web/20210415002501/https://books.google.com/books?id=NSu5BAAAQBAJ&pg=PA131|url-status=live}}</ref><ref>{{cite book|author=James B. Kaler|title=Stars and Their Spectra: An Introduction to the Spectral Sequence|url=https://books.google.com/books?id=ZEKO2pzuRHoC&pg=PA241|date=28 July 2011|publisher=Cambridge University Press|isbn=978-0-521-89954-3|pages=241–|access-date=7 June 2019|archive-date=15 April 2021|archive-url=https://web.archive.org/web/20210415002501/https://books.google.com/books?id=ZEKO2pzuRHoC&pg=PA241|url-status=live}}</ref> As many of its common names allude, its shape is said to resemble a [[Ladle (spoon)|ladle]], an agricultural [[plough]], or [[wagon]]. In the context of Ursa Major, they are commonly drawn to represent the hindquarters and tail of the Great Bear. Starting with the "ladle" portion of the dipper and extending clockwise (eastward in the sky) through the handle, these stars are the following: {{flowlist}} * [[Dubhe]] ("the bear"), which at a magnitude of 1.79 is the 35th-brightest star in the sky and the second-brightest of Ursa Major. * [[Merak (star)|Merak]] ("the loins of the bear"), with a magnitude of 2.37. * [[Phecda]] ("thigh"), with a magnitude of 2.44. * [[Megrez]], meaning "root of the tail", referring to its location as the intersection of the body and tail of the bear (or the ladle and handle of the dipper). * [[Alioth]], a name which refers not to a bear but to a "black horse", the name corrupted from the original and mis-assigned to the similarly named ''Alcor'', the naked-eye binary companion of ''Mizar''.<ref name=kaler>{{cite web |author=Jim Kaler |title=Stars: "Alioth" |date=2009-09-16 |url=http://stars.astro.illinois.edu/sow/alioth.html |access-date=2019-06-07 |author-link=Jim Kaler |archive-date=2019-12-11 |archive-url=https://web.archive.org/web/20191211104920/http://stars.astro.illinois.edu/sow/alioth.html |url-status=live }}</ref> Alioth is the brightest star of Ursa Major and the 33rd-brightest in the sky, with a magnitude of 1.76. It is also the brightest of the [[chemically peculiar star|chemically peculiar]] [[Ap star]]s, magnetic stars whose chemical elements are either depleted or enhanced, and appear to change as the star rotates.<ref name=kaler/> * [[Mizar]], ζ Ursae Majoris, the second star in from the end of the handle of the Big Dipper, and the constellation's fourth-brightest star. ''Mizar'', which means "girdle", forms a famous [[double star]], with its optical companion [[Alcor (star)|Alcor]] (80 Ursae Majoris), the two of which were termed the "horse and rider" by the Arabs. * [[Alkaid]], known as η Ursae Majoris, is situated at the end of the tail. With a magnitude of 1.85, Alkaid is the third-brightest star of Ursa Major.<ref>{{cite book|author=Mark R. Chartrand|title=Skyguide, a Field Guide for Amateur Astronomers|url=https://books.google.com/books?id=pk-RQgAACAAJ|year=1982|publisher=Golden Press|isbn=978-0-307-13667-1|bibcode=1982sfga.book.....C|access-date=2019-06-07|archive-date=2021-04-15|archive-url=https://web.archive.org/web/20210415002502/https://books.google.com/books?id=pk-RQgAACAAJ|url-status=live}}</ref><ref>Ridpath, at p. 136.</ref> {{endflowlist}} Except for ''Dubhe'' and ''Alkaid'', the stars of the Big Dipper all have [[proper motion]]s heading toward a common point in [[Sagittarius (constellation)|Sagittarius]]. A few other such stars have been identified, and together they are called the [[Ursa Major Moving Group]]. [[File:Ursa Major - Ursa Minor - Polaris.jpg|thumb|upright=1.35|Ursa Major and Ursa Minor in relation to Polaris]] The stars Merak (β Ursae Majoris) and Dubhe (α Ursae Majoris) are known as the "pointer stars" because they are helpful for finding [[Polaris]], also known as the [[North Star]] or Pole Star. By visually tracing a line from Merak through Dubhe (1 unit) and continuing for 5 units, one's eye will land on Polaris, accurately indicating true north. Another asterism representing three pairs of footprints of a leaping gazelle<ref>{{cite web|author=Ian Ridpath|title=Star Tales – Ursa Major|url=http://www.ianridpath.com/startales/ursamajor2.html#leaps}}</ref> is recognized in [[Arab culture]]. It is a series of three pairs of stars found along the southern border of the constellation. From southeast to southwest, the "first leap", comprising [[Nu Ursae Majoris|ν]] and [[ξ Ursae Majoris]] (Alula Borealis and Australis, respectively); the "second leap", comprising [[Lambda Ursae Majoris|λ]] and [[μ Ursae Majoris]] (Tania Borealis and Australis); and the "third leap", comprising [[Iota Ursae Majoris|ι]] and [[κ Ursae Majoris]], (Talitha Borealis and Australis respectively).
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