Editing Ursa Major (section)

==Features==

{{See also|List of stars in Ursa Major}}

===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).

===Other stars===
[[W Ursae Majoris]] is the prototype of a class of [[contact binary]] [[variable star]]s, and ranges between 7.75<sup>[[apparent magnitude|m]]</sup> and 8.48<sup>m</sup>.

[[47 Ursae Majoris]] is a Sun-like star with a three-planet [[extrasolar planet|system]].{{sfn|Levy|2005|p=67}} [[47 Ursae Majoris b]], discovered in 1996, orbits every 1078 days and is 2.53 times the [[mass of Jupiter]].<ref>{{cite encyclopedia |url = https://exoplanet.eu/catalog/47_uma_b--71/ |title = Planet 47 Uma b |date = 11 July 2012 |access-date = 15 July 2012 |archive-date = 11 November 2023 |archive-url = https://web.archive.org/web/20231111213322/https://exoplanet.eu/catalog/47_uma_b--71/ |encyclopedia = [[Extrasolar Planets Encyclopaedia]] |url-status = live }}</ref> [[47 Ursae Majoris c]], discovered in 2001, orbits every 2391 days and is 0.54 times the mass of Jupiter.<ref>{{cite encyclopedia |url = https://exoplanet.eu/catalog/47_uma_c--72/ |title = Planet 47 Uma c |date = 11 July 2012 |access-date = 15 July 2012 |url-status = live |archive-url = https://web.archive.org/web/20231111213317/https://exoplanet.eu/catalog/47_uma_c--72/ |encyclopedia = [[Extrasolar Planets Encyclopaedia]] |archive-date = 11 November 2023 }}</ref> [[47 Ursae Majoris d]], discovered in 2010, has an uncertain period, lying between 8907 and 19097 days; it is 1.64 times the mass of Jupiter.<ref>{{cite encyclopedia |url = https://exoplanet.eu/catalog/47_uma_d--648/ |title = Planet 47 Uma d |date = 11 July 2012 |access-date = 15 July 2012 |url-status = live |archive-url = https://web.archive.org/web/20231111213318/https://exoplanet.eu/catalog/47_uma_d--648/ |encyclopedia = [[Extrasolar Planets Encyclopaedia]] |archive-date = 11 November 2023 }}</ref> The star is of magnitude 5.0 and is approximately 46 light-years from Earth.{{sfn|Levy|2005|p=67}}

The star TYC 3429-697-1 ({{RA|9|40|44}} {{DEC|48|14|2}}), located to the east of [[θ Ursae Majoris]] and to the southwest of the "Big Dipper") has been recognized as the [[List of Delaware state symbols|state star]] of [[Delaware]], and is informally known as the Delaware Diamond.<ref name=a>{{cite web |url=http://delaware.gov/topics/facts/misc.shtml |title=Delaware Facts & Symbols – Delaware Miscellaneous Symbols |website=delaware.gov |access-date=2019-06-07 |archive-date=2019-03-28 |archive-url=https://web.archive.org/web/20190328213054/https://delaware.gov/topics/facts/misc.shtml |url-status=live }}</ref>

===Deep-sky objects===
[[File:M101 hires STScI-PRC2006-10a.jpg|thumb|right|250px|The Pinwheel Galaxy]]
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 spiral northeast of [[Alkaid]]. The spiral galaxies [[Messier 108]] and [[Messier 109]] are also found in this constellation. The bright [[planetary nebula]] [[Owl Nebula]] (M97) can be found along the bottom of the bowl of the Big Dipper.

[[Messier 81|M81]] is a nearly face-on [[spiral galaxy]] 11.8&nbsp;million light-years from Earth. Like most spiral galaxies, it has a core made up of old stars, with arms filled with young stars and [[nebula]]e. Along with [[Messier 82|M82]], it is a part of the [[galaxy cluster]] closest to the [[Local Group]].

[[Messier 82|M82]] is a nearly edgewise galaxy that is [[galaxy merger|interacting gravitationally]] with M81. It is the brightest [[infrared spectrum|infrared galaxy]] in the sky.<ref name="objects">{{cite book |title = 300 Astronomical Objects: A Visual Reference to the Universe |last1=Wilkins |first1=Jamie |last2=Dunn |first2 = Robert |publisher = Firefly Books |date = 2006 |edition = 1st |location=Buffalo, New York |isbn = 978-1-55407-175-3}}</ref> [[SN 2014J]], an apparent [[Type Ia supernova]], was observed in M82 on 21 January 2014.<ref>{{cite journal|bibcode=2014ATel.5786....1C|title=Classification of Supernova in M82 as a young, reddened Type Ia Supernova|journal=The Astronomer's Telegram|volume=5786|pages=1|last1=Cao|first1=Y|last2=Kasliwal|first2=M. M|last3=McKay|first3=A|last4=Bradley|first4=A|year=2014}}</ref>

[[Messier 97|M97]], also called the Owl Nebula, is a [[planetary nebula]] 1,630 light-years from Earth; it has a magnitude of approximately 10. It was discovered in 1781 by [[Pierre Méchain]].{{sfn|Levy|2005|pp=129–130}}

[[Messier 101|M101]], also called the Pinwheel Galaxy, is a face-on spiral galaxy located 25 million light-years from Earth. It was discovered by Pierre Méchain in 1781. Its spiral arms have regions with extensive [[star formation]] and have strong [[ultraviolet|ultraviolet emissions]].<ref name="objects"/> It has an [[integrated magnitude]] of 7.5, making it visible in both binoculars and telescopes, but not to the naked eye.<ref>{{cite journal |title = M101: A Bear of a Galaxy |last = Seronik |first = Gary |journal = Sky & Telescope |date = July 2012 |volume = 124 |issue = 1|page = 45 |bibcode = 2012S&T...124a..45S }}</ref>

[[NGC 2787]] is a [[lenticular galaxy]] at a distance of 24 million light-years. Unlike most lenticular galaxies, NGC 2787 has a [[barred spiral galaxy|bar]] at its center. It also has a halo of [[globular cluster]]s, indicating its age and relative stability.<ref name="objects"/>

[[NGC 2950]] is a lenticular galaxy located 60 million light-years from Earth.

[[NGC 3000]] is a double star, and catalogued as a nebula-type object.

[[NGC 3079]] is a [[starburst galaxy|starburst]] spiral galaxy located 52 million light-years from Earth. It has a horseshoe-shaped structure at its center that indicates the presence of a [[supermassive black hole]]. The structure itself is formed by [[superwind]]s from the black hole.<ref name="objects"/>

[[NGC 3310]] is another starburst spiral galaxy located 50 million light-years from Earth. Its bright white color is caused by its higher than usual rate of star formation, which began 100&nbsp;million years ago after a merger. Studies of this and other starburst galaxies have shown that their starburst phase can last for hundreds of millions of years, far longer than was previously assumed.<ref name="objects"/>

[[NGC 4013]] is an edge-on spiral galaxy located 55 million light-years from Earth. It has a prominent [[dust lane]] and has several visible star forming regions.<ref name="objects"/>

[[I Zwicky 18]] is a young dwarf galaxy at a distance of 45 million light-years. The youngest-known galaxy in the visible universe, I&nbsp;Zwicky 18 is about 4&nbsp;million years old, about one-thousandth the age of the [[Solar System]]. It is filled with star forming regions which are creating many hot, young, blue stars at a very high rate.<ref name="objects"/>

The [[Hubble Deep Field]] is located to the northeast of [[Delta Ursae Majoris|δ Ursae Majoris]].

===Meteor showers===

* The '''Alpha Ursae Majorids''' are a minor meteor shower in the constellation.<ref name=":0">{{cite journal |last1=Hajduková |first1=M. |last2=Neslušan |first2=L. |year=2020 |title=The χ-Andromedids and January α-Ursae Majorids: A new and a probable shower associated with Comet C/1992 W1 (Ohshita) |journal=Icarus |volume=351 |page=113960 |bibcode=2020Icar..35113960H |doi=10.1016/j.icarus.2020.113960 |s2cid=224889918}}</ref> They may be caused by the comet  C/1992 W1 (Ohshita).<ref name=":0" /><ref>{{Cite journal |last1=Hajdukova |first1=Maria |last2=Neslušan |first2=Luboš |date=2021-06-28 |title=Unknown sibling showers of comets C/1992 W1 (Ohshita) and C/1853 G1 (Schweizer) |url=https://meetingorganizer.copernicus.org/EPSC2021/EPSC2021-214.html |journal=[[Europlanet Science Congress 2021]] |doi=10.5194/epsc2021-214 |bibcode=2021EPSC...15..214H |language=en |doi-access=free |url-access=subscription }}</ref>
* The '''[[Kappa Ursae Majorids]]''' are a newly discovered [[meteor shower]], peaking between November&nbsp;1 and November&nbsp;10.<ref>{{cite journal |journal = Sky & Telescope |date = September 2012 |last = Jenniskens |first = Peter |page = 23 |title = Mapping Meteoroid Orbits: New Meteor Showers Discovered}}</ref>
* The '''October Ursae Majorids''' were discovered in 2006 by Japanese researchers. They may be caused may be a long period comet.<ref>{{Cite journal |last=Gajdoš |first=Štefan |date=2008-06-01 |title=Search for Past Signs of October Ursae Majorids |url=https://doi.org/10.1007/s11038-007-9196-9 |journal=Earth, Moon, and Planets |language=en |volume=102 |issue=1 |pages=117–123 |doi=10.1007/s11038-007-9196-9 |bibcode=2008EM&P..102..117G |s2cid=123555821 |issn=1573-0794|url-access=subscription }}</ref> The shower peaks between October&nbsp;12 and 19.<ref>{{Cite web |title=October Ursa Majorids – Watch the Skies |url=https://blogs.nasa.gov/Watch_the_Skies/tag/october-ursa-majorids/ |access-date=2023-03-30 |website=blogs.nasa.gov |date=18 October 2011 |language=en-US}}</ref>

===Extrasolar planets===
[[HD 80606]], a sun-like star in a binary system, orbits a common center of gravity with its partner, [[HD 80607]]; the two are separated by 1,200&nbsp;AU on average. Research conducted in 2003 indicates that its sole planet, [[HD 80606 b]] is a future [[hot Jupiter]], modeled to have evolved in a perpendicular orbit around 5&nbsp;AU from its sun. The 4-Jupiter mass planet is projected to eventually move into a circular, more aligned orbit via the [[Kozai mechanism]]. However, it is currently on an incredibly [[orbital eccentricity|eccentric orbit]] that ranges from approximately one astronomical unit at its [[apoapsis]] and six stellar radii at [[periapsis]].<ref>{{cite journal |title = How Worlds Get Out of Whack |first = Greg |last = Laughlin |journal = Sky and Telescope |date = May 2013 |volume = 125 |issue = 5 |page = 29|bibcode = 2013S&T...125e..26L }}</ref>