Visible at latitudes between +90° and −30°. Best visible at 21:00 (9 p.m.) during the month of April. TheBig Dipper or Plough
Ursa Major, also known as theGreat Bear, is aconstellation in theNorthern Sky, whose associated mythology likely dates back into prehistory. Its Latin name means "greater (or larger) bear", referring to and contrasting it with nearbyUrsa Minor, the lesser bear.[2] Inantiquity, it was one of the original 48 constellations listed byPtolemy in the 2nd century AD, drawing on earlier works by Greek, Egyptian, Babylonian, and Assyrian astronomers.[3] Today it is the third largest of the88 modern constellations.
Ursa Major is primarily known from theasterism of its main seven stars, which has been called the "Big Dipper", "the Wagon", "Charles's Wain", or "the Plough", among other names. In particular, the Big Dipper's stellar configuration mimics the shape of the "Little Dipper". Two of its stars, namedDubhe andMerak (α Ursae Majoris andβ Ursae Majoris), can be used as the navigational pointer towards the place of the currentnorthern pole star,Polaris inUrsa Minor.
Ursa Major, along with asterisms it contains or overlaps, is significant to numerous world cultures, often as a symbol of the north. Its depiction on theflag of Alaska is a modern example of such symbolism.
Ursa Major is visible throughout the year from most of theNorthern Hemisphere, and appearscircumpolar above the mid-northern latitudes. From southern temperate latitudes, the main asterism is invisible, but the southern parts of the constellation can still be viewed.
Ursa Major covers 1279.66 square degrees or 3.10% of the total sky, making it the third largest constellation.[4] In 1930,Eugène Delporte set its official International Astronomical Union (IAU) constellation boundaries, defining it as a 28-sided irregular polygon. In theequatorial coordinate system, the constellation stretches between theright ascension coordinates of08h 08.3m and14h 29.0m and thedeclination coordinates of +28.30° and +73.14°.[5] Ursa Major borders eight other constellations:Draco to the north and northeast,Boötes to the east,Canes Venatici to the east and southeast,Coma Berenices to the southeast,Leo andLeo Minor to the south,Lynx to the southwest andCamelopardalis to the northwest. The three-letter constellation abbreviation "UMa" was adopted by the IAU in 1922.[5]
Ursa Major and Polaris with names of bright stars in the Big DipperThe constellation Ursa Major as it can be seen by the unaided eye
The outline of the seven bright stars of Ursa Major form theasterism known as the "Big Dipper" in the United States and Canada, while in the United Kingdom it is called thePlough[6] or (historically)Charles' Wain.[7] Six of the seven stars are ofsecond magnitude or higher, and it forms one of the best-known patterns in the sky.[8][9] As many of its common names allude, its shape is said to resemble aladle, an agriculturalplough, orwagon. 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:
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 ("the loins of the bear"), with a magnitude of 2.37.
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 namedAlcor, the naked-eye binary companion ofMizar.[10] 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 thechemically peculiarAp stars, magnetic stars whose chemical elements are either depleted or enhanced, and appear to change as the star rotates.[10]
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 famousdouble star, with its optical companionAlcor (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.[11][12]
Except forDubhe andAlkaid, the stars of the Big Dipper all haveproper motions heading toward a common point inSagittarius. A few other such stars have been identified, and together they are called theUrsa Major Moving Group.
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 findingPolaris, also known as theNorth 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 is recognized inArab culture as representing three pairs of footprints of a leaping gazelle.[13] It is a series of three pairs of stars found along the southern border of the constellation. From southeast to southwest, the "first leap", comprisingν andξ Ursae Majoris (Alula Borealis and Australis, respectively); the "second leap", comprisingλ andμ Ursae Majoris (Tania Borealis and Australis); and the "third leap", comprisingι andκ Ursae Majoris (Talitha and Alkaphrah). The same asterism has the Chinese nameSantai[13] and the Indian nameTrivikrama,[14] both meaning "three steps".
47 Ursae Majoris is a Sun-like star with a three-planetsystem.[15]47 Ursae Majoris b, discovered in 1996, orbits every 1078 days and is 2.53 times themass of Jupiter.[16]47 Ursae Majoris c, discovered in 2001, orbits every 2391 days and is 0.54 times the mass of Jupiter.[17]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.[18] The star is of magnitude 5.0 and is approximately 46 light-years from Earth.[15]
The star TYC 3429-697-1 (9h 40m 44s 48° 14′ 2″), located to the east ofθ Ursae Majoris and to the southwest of the "Big Dipper") has been recognized as thestate star ofDelaware, and is informally known as the Delaware Diamond.[19]
Several brightgalaxies are found in Ursa Major, including the pairMessier 81 (one of the brightest galaxies in the sky) andMessier 82 above the bear's head, andPinwheel Galaxy (M101), a spiral northeast ofAlkaid. The spiral galaxiesMessier 108 andMessier 109 are also found in this constellation. The brightplanetary nebulaOwl Nebula (M97) can be found along the bottom of the bowl of the Big Dipper.
M81 is a nearly face-onspiral galaxy 11.8 million light-years from Earth. Like most spiral galaxies, it has a core made up of old stars, with arms filled with young stars andnebulae. Along withM82, it is a part of thegalaxy cluster closest to theLocal Group.
M97, also called the Owl Nebula, is aplanetary nebula 1,630 light-years from Earth; it has a magnitude of approximately 10. It was discovered in 1781 byPierre Méchain.[22]
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 extensivestar formation and have strongultraviolet emissions.[20] It has anintegrated magnitude of 7.5, making it visible in both binoculars and telescopes, but not to the naked eye.[23]
NGC 2787 is alenticular galaxy at a distance of 24 million light-years. Unlike most lenticular galaxies, NGC 2787 has abar at its center. It also has a halo ofglobular clusters, indicating its age and relative stability.[20]
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 astarburst spiral galaxy located 52 million light-years from Earth. It has a horseshoe-shaped structure at its center that indicates the presence of asupermassive black hole. The structure itself is formed bysuperwinds from the black hole.[20]
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 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.[20]
NGC 4013 is an edge-on spiral galaxy located 55 million light-years from Earth. It has a prominentdust lane and has several visible star forming regions.[20]
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 Zwicky 18 is about 4 million years old, about one-thousandth the age of theSolar System. It is filled with star forming regions which are creating many hot, young, blue stars at a very high rate.[20]
TheOctober Ursae Majorids were discovered in 2006 by Japanese researchers. They may be caused may be a long period comet.[27] The shower peaks between October 12 and 19.[28]
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 AU on average. Research conducted in 2003 indicates that its sole planet,HD 80606 b is a futurehot Jupiter, modeled to have evolved in a perpendicular orbit around 5 AU from its sun. The 4-Jupiter mass planet is projected to eventually move into a circular, more aligned orbit via theKozai mechanism. However, it is currently on an incrediblyeccentric orbit that ranges from approximately one astronomical unit at itsapoapsis and six stellar radii atperiapsis.[29]
Ursa Major shown on a carved stone, c. 1700,Crail, Fife
Ursa Major has been reconstructed as anIndo-European constellation.[30] It was one of the 48 constellations listed by the 2nd century AD astronomerPtolemy in hisAlmagest, who called it Arktos Megale.[a]
The constellation of Ursa Major has been seen as abear, usually female,[32] by multiple connected civilizations.[33] This may stem from a commonoral tradition ofCosmic Hunt myths stretching back more than 13,000 years.[34] Using statistical and phylogenetic tools, Julien d'Huy reconstructs the following Palaeolithic state of the story: "There is an animal that is a horned herbivore, especially an elk. One human pursues this ungulate. The hunt locates or get to the sky. The animal is alive when it is transformed into a constellation. It forms the Big Dipper."[35]
Whilst thePre-Islamic Arabs recognised the larger constellation of Ursa Major as being a bear, perhaps due to Greek influence, they had traditionally always recognised the Big Dipper and Ursa Minor as being counterparts. Both were imagined as funeral processions with the ladle of either seen as a funerarybier and its handle as a train of mourners. The Big Dipper is known asbanāt an-na'sh al-kubrā meaning literally "the greater daughters of the bier". However daughters here meansthose pertaining to it, i.e.the mourners and thus is better translated as "the greater funeral procession", whilst Ursa Minor is known as "the lesser funeral procession". There is also a legend that the body on the bier is the father of those following behind it, a man calledNa'ash who was murdered byAl-judayy (the Arabic name forthe North Star) and whom the funeral procession is in pursuit of.[36]
InGreek mythology,Zeus (the king of the gods, known asJupiter inRoman mythology) lusts after a young woman namedCallisto, anymph ofArtemis (known to the Romans asDiana). Zeus's jealous wifeHera (Juno to the Romans) discovers that Callisto has a son named Arcas as the result of her rape by Zeus and transforms Callisto into a bear as a punishment.[37] Callisto, while in bear form, later encounters her sonArcas. Arcas almost spears the bear, but to avert the tragedy Zeus whisks them both into the sky, Callisto as Ursa Major and Arcas as the constellationBoötes.Ovid called Ursa Major the Parrhasian Bear, since Callisto came fromParrhasia inArcadia, where the story is set.[38]
The Greek poetAratus called the constellation Helike, ("turning" or "twisting"), because it turns around the celestial pole. TheOdyssey notes that it is the sole constellation that never sinks below the horizon and "bathes in the Ocean's waves", so it is used as a celestial reference point fornavigation.[39] It has also been called the "Wain" or "Plaustrum", a Latin word referring to a horse-drawn cart.[40]
InHinduism, The earliest mention of Ursa Major/Big dipper/ Great Bear is known asSaptarshi, each of the stars representing one of the Saptarishis or Seven Sages (Rishis) viz.Bhrigu,Atri,Angiras,Vasishtha,Pulastya,Pulaha, andKratu. is found in the Rigveda (c. 1500–1200 BCE), one of the oldest known texts in human history.
References in Ancient Indian Texts:
Rigveda (Mandala 1, Hymn 24.10). Mentions the Saptarishi in connection with celestial order and cosmic significance.
Mahabharata (c. 400 BCE – 400 CE). Discusses Saptarishi Mandal as a guiding star for navigation.
Puranas (Vishnu Purana, Brahmanda Purana, and others). Describe the Saptarishis as divine sages who hold cosmic wisdom.
For Ursa Minor, it was not explicitly mentioned in early Vedic texts but was recognized in later astronomical texts such as:
Vedanga Jyotisha (c. 1400–1200 BCE)
Surya Siddhanta (c. 4th century CE)
The fact that the two front stars of the constellations point to the pole star is explained as the boon given to the boy sageDhruva by LordVishnu.[41]
Thus, the Rigveda holds the earliest recorded mention of Ursa Major, while Ursa Minor gained prominence in later astronomical traditions.
In China and Japan, the Big Dipper is called the "North Dipper"北斗 (Chinese:běidǒu,Japanese:hokuto), and in ancient times, each one of the seven stars had a specific name, often coming themselves from ancient China:
"Pivot"樞 (C:shū J:sū) is for Dubhe (Alpha Ursae Majoris)
"Beautiful jade"璇 (C:xuán J:sen) is for Merak (Beta Ursae Majoris)
"Pearl"璣 (C:jī J:ki) is for Phecda (Gamma Ursae Majoris)
"Balance"[43]權 (C:quán J:ken) is for Megrez (Delta Ursae Majoris)
"Measuring rod of jade"玉衡 (C:yùhéng J:gyokkō) is for Alioth (Epsilon Ursae Majoris)
"Opening of the Yang"開陽 (C:kāiyáng J:kaiyō) is for Mizar (Zeta Ursae Majoris)
Alkaid (Eta Ursae Majoris) has several nicknames: "Sword"劍 (C:jiàn J:ken) (short form from "End of the sword"劍先 (C:jiàn xiān J:ken saki)), "Flickering light"搖光 (C:yáoguāng J:yōkō), or again "Star of military defeat"破軍星 (C:pójūn xīng J:hagun sei), because travel in the direction of this star was regarded as bad luck for an army.[44]
InShinto, the seven largest stars of Ursa Major belong toAme-no-Minakanushi, the oldest and most powerful of allkami.
InSouth Korea, the constellation is referred to as "the seven stars of the north". In the related myth, a widow with seven sons found comfort with a widower, but to get to his house required crossing a stream. The seven sons, sympathetic to their mother, placed stepping stones in the river. Their mother, not knowing who put the stones in place, blessed them and, when they died, they became the constellation.
TheIroquois 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.
TheLakota people call the constellationWičhákhiyuhapi, or "Great Bear".
TheWampanoag people (Algonquian) referred to Ursa Major as "maske", meaning "bear" according to Thomas Morton in The New England Canaan.[45]
TheWasco-Wishram Native Americans interpreted the constellation as five wolves and two bears that were left in the sky byCoyote.[46]
ToNorse pagans, the Big Dipper was known asÓðins vagn, "Woden's wagon". Likewise Woden ispoetically referred to byKennings such asvagna verr 'guardian of the wagon' orvagna rúni 'confidant of the wagon'[47]
In theFinnish language, the asterism is sometimes called by its old Finnish name,Otava. The meaning of the name has been almost forgotten in Modern Finnish; it means asalmonweir. Ancient Finns believed thebear (Ursus arctos) was lowered to earth in a golden basket off the Ursa Major, and when a bear was killed, its head was positioned on a tree to allow the bear's spirit to return to Ursa Major.
In theSámi languages of Northern Europe, part of the constellation (i.e. theBig Dipper minusDubhe andMerak, is identified as thebow of the great hunter Fávdna (the starArcturus). In the main Sámi language,North Sámi, it is calledFávdnadávgi ("Fávdna's Bow") or simplydávggát ("the Bow"). The constellation features prominently in theSámi anthem, which begins with the wordsGuhkkin davvin dávggaid vuolde sabmá suolggai Sámieanan, which translates to "Far to the north, under the Bow, the Land of the Sámi slowly comes into view." The Bow is an important part of the Sámi traditional narrative about the night sky, in which various hunters try to chase downSarva, the Great Reindeer, a large constellation that takes up almost half the sky. According to the legend, Fávdna stands ready to fire his Bow every night but hesitates because he might hitStella Polaris, known asBoahji ("the Rivet"), which would cause the sky to collapse and end the world.[48]
InBurmese,Pucwan Tārā (ပုဇွန် တာရာ,[bəzʊ̀ɴtàjà]) is the name of a constellation comprising stars from the head and forelegs of Ursa Major;pucwan (ပုဇွန်) is a general term for acrustacean, such asprawn,shrimp,crab,lobster, etc.
InJavanese, it is known as "lintang jong", which means "thejong constellation". Likewise, inMalay it is called "bintang jong".[49]
In European star charts, the constellation was visualized with the 'square' of the Big Dipper forming the bear's body and the chain of stars forming the Dipper's "handle" as a long tail. However, bears do not have long tails, and Jewish astronomers considered Alioth, Mizar, and Alkaid instead to be three cubs following their mother, while the Native Americans saw them as three hunters.
H. A. Rey's alternative asterism for Ursa Major can be said to give it the longer head and neck of a polar bear, as seen in this photo, from theleft side.
Noted children's book authorH. A. Rey, in his 1952 bookThe Stars: A New Way to See Them, (ISBN0-395-24830-2) had a differentasterism in mind for Ursa Major, that instead had the "bear" image of the constellation oriented with Alkaid as the tip of the bear's nose, and the "handle" of the Big Dipper part of the constellation forming the outline of the top of the bear's head and neck, rearwards to the shoulder, potentially giving it the longer head and neck of apolar bear.[54]
Ursa Major as depicted inUrania's Mirror, a set of constellation cards published in London c.1825
Johannes Hevelius drew Ursa Major as if being viewed from outside the celestial sphere.
^abcdefgWilkins, Jamie; Dunn, Robert (2006).300 Astronomical Objects: A Visual Reference to the Universe (1st ed.). Buffalo, New York: Firefly Books.ISBN978-1-55407-175-3.
^Cao, Y;Kasliwal, M. M; McKay, A; Bradley, A (2014). "Classification of Supernova in M82 as a young, reddened Type Ia Supernova".The Astronomer's Telegram.5786: 1.Bibcode:2014ATel.5786....1C.
^Laughlin, Greg (May 2013). "How Worlds Get Out of Whack".Sky and Telescope.125 (5): 29.Bibcode:2013S&T...125e..26L.
^Mallory, J.P.; Adams, D.Q. (August 2006). "Chapter 8.5: The Physical Landscape of the Proto-Indo-Europeans".Oxford Introduction to Proto-Indo-European and the Proto-Indo-European World. Oxford, GBR: Oxford University Press. p. 131.ISBN9780199287918.OCLC139999117.The most solidly 'reconstructed' Indo-European constellation is Ursa Major, which is designated as 'The Bear' (Chapter 9) in Greek and Sanskrit (Latin may be a borrowing here), although even the latter identification has been challenged.
^Gibbon, William B. (1964). "Asiatic parallels in North American star lore: Ursa Major".Journal of American Folklore.77 (305):236–250.doi:10.2307/537746.JSTOR537746.
^TheBansenshukai, written in 1676 by the ninja master Fujibayashi Yasutake, speak several times about these stars, and show a traditional picture of the Big Dipper in his book 8, volume 17, speaking about astronomy and meteorology (from Axel Mazuer's translation).
^Thomas, Morton (13 September 1883).The new English Canaan of Thomas Morton. Published by the Prince Society.OL7142058M.
^Clayson, Hollis (2002). "Exhibition Review: "Some Things Bear Fruit"? Witnessing the Bonds between Van Gogh and Gauguin".The Art Bulletin.84 (4):670–684.doi:10.2307/3177290.ISSN0004-3079.JSTOR3177290.
Thompson, Robert; Thompson, Barbara (2007).Illustrated Guide to Astronomical Wonders: From Novice to Master Observer. O'Reilly Media, Inc.ISBN978-0-596-52685-6.
