Constellation | |
Abbreviation | UMa |
---|---|
Genitive | Ursae Majoris |
Pronunciation | /ˌɜːrsəˈmeɪdʒər/ UR-sə MAY-jər, genitive /ˌɜːrsiːməˈdʒɔːrɪs/ UR-see mə-JOR-iss |
Symbolism | the Great Bear |
Right ascension | 10.67h |
Declination | +55.38° |
Quadrant | NQ2 |
Area | 1280 sq. deg. (3rd) |
Main stars | 7, 20 |
Bayer/Flamsteed stars | 93 |
Stars with planets | 21 |
Stars brighter than 3.00m | 7 |
Stars within 10.00 pc (32.62 ly) | 8 |
Brightest star | Alioth (ε UMa) (1.76 m ) |
Messier objects | 7 |
Meteor showers | Alpha Ursae Majorids Kappa Ursae Majorids October Ursae Majorids |
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 or Plough |
Ursa Major, also known as the Great Bear, is a constellation in the northern sky, whose associated mythology likely dates back into prehistory. Its Latin name means "greater (or larger) bear", referring to and contrasting it with nearby Ursa Minor, the lesser bear. [1] In antiquity, it was one of the original 48 constellations listed by Ptolemy in the 2nd century AD, drawing on earlier works by Greek, Egyptian, Babylonian, and Assyrian astronomers. [2] Today it is the third largest of the 88 modern constellations.
Ursa Major is primarily known from the asterism 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, named Dubhe and Merak (α Ursae Majoris and β Ursae Majoris), can be used as the navigational pointer towards the place of the current northern pole star, Polaris in Ursa 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 the flag of Alaska is a modern example of such symbolism.
Ursa Major is visible throughout the year from most of the Northern Hemisphere, and appears circumpolar 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. [3] In 1930, Eugène Delporte set its official International Astronomical Union (IAU) constellation boundaries, defining it as a 28-sided irregular polygon. In the equatorial coordinate system, the constellation stretches between the right ascension coordinates of 08h 08.3m and 14h 29.0m and the declination coordinates of +28.30° and +73.14°. [4] 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 and Leo Minor to the south, Lynx to the southwest and Camelopardalis to the northwest. The three-letter constellation abbreviation "UMa" was adopted by the IAU in 1922. [5]
The outline of the seven bright stars of Ursa Major form the asterism known as the " Big Dipper " in the United States and Canada, while in the United Kingdom it is called the Plough [6] or (historically) Charles' Wain. [7] Six of the seven stars are of second 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 a 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:
Except for Dubhe and Alkaid, the stars of the Big Dipper all have proper motions heading toward a common point in Sagittarius. A few other such stars have been identified, and together they are called the Ursa Major Moving Group.
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 [13] 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 ν and ξ Ursae Majoris (Alula Borealis and Australis, respectively); the "second leap", comprising λ and μ Ursae Majoris (Tania Borealis and Australis); and the "third leap", comprising ι and κ Ursae Majoris, (Talitha Borealis and Australis respectively).
W Ursae Majoris is the prototype of a class of contact binary variable stars, and ranges between 7.75 m and 8.48m.
47 Ursae Majoris is a Sun-like star with a three-planet system. [14] 47 Ursae Majoris b, discovered in 1996, orbits every 1078 days and is 2.53 times the mass of Jupiter. [15] 47 Ursae Majoris c, discovered in 2001, orbits every 2391 days and is 0.54 times the mass of Jupiter. [16] 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. [17] The star is of magnitude 5.0 and is approximately 46 light-years from Earth. [14]
The star TYC 3429-697-1 (9h 40m 44s48° 14′ 2″), located to the east of θ Ursae Majoris and to the southwest of the "Big Dipper") has been recognized as the state star of Delaware, and is informally known as the Delaware Diamond. [18]
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.
M81 is a nearly face-on spiral 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 and nebulae. Along with M82, it is a part of the galaxy cluster closest to the Local Group.
M82 is a nearly edgewise galaxy that is interacting gravitationally with M81. It is the brightest infrared galaxy in the sky. [19] SN 2014J, an apparent Type Ia supernova, was observed in M82 on 21 January 2014. [20]
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. [21]
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 emissions. [19] It has an integrated magnitude of 7.5, making it visible in both binoculars and telescopes, but not to the naked eye. [22]
NGC 2787 is a lenticular galaxy at a distance of 24 million light-years. Unlike most lenticular galaxies, NGC 2787 has a bar at its center. It also has a halo of globular clusters, indicating its age and relative stability. [19]
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 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 superwinds from the black hole. [19]
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. [19]
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. [19]
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 the Solar System. It is filled with star forming regions which are creating many hot, young, blue stars at a very high rate. [19]
The Hubble Deep Field is located to the northeast of δ Ursae Majoris.
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 future hot 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 the Kozai mechanism. However, it is currently on an incredibly eccentric orbit that ranges from approximately one astronomical unit at its apoapsis and six stellar radii at periapsis. [28]
Ursa Major has been reconstructed as an Indo-European constellation. [29] It was one of the 48 constellations listed by the 2nd century AD astronomer Ptolemy in his Almagest , who called it Arktos Megale. [lower-alpha 1] It is mentioned by such poets as Homer, Spenser, Shakespeare, Tennyson and also by Federico Garcia Lorca, in "Song for the Moon". [31] Ancient Finnish poetry also refers to the constellation, and it features in the painting Starry Night Over the Rhône by Vincent van Gogh. [32] [33] It may be mentioned in the biblical book of Job, dated between the 7th and 4th centuries BC, although this is often disputed. [34]
This section needs additional citations for verification .(April 2019) |
The constellation of Ursa Major has been seen as a bear, usually female, [35] by many distinct civilizations. [36] This may stem from a common oral tradition of Cosmic Hunt myths stretching back more than 13,000 years. [37] 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." [38]
In Greek mythology, Zeus (the king of the gods, known as Jupiter in Roman mythology) lusts after a young woman named Callisto, a nymph of Artemis (known to the Romans as Diana). Zeus's jealous wife Hera (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. [39] Callisto, while in bear form, later encounters her son Arcas. 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 constellation Boötes. Ovid called Ursa Major the Parrhasian Bear, since Callisto came from Parrhasia in Arcadia, where the story is set. [40]
The Greek poet Aratus called the constellation Helike, ("turning" or "twisting"), because it turns around the celestial pole. The Odyssey 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 for navigation. [41] It has also been called the "Wain" or "Plaustrum", a Latin word referring to a horse-drawn cart. [42]
In Hinduism, Ursa Major/Big dipper/ Great Bear is known as Saptarshi, each of the stars representing one of the Saptarishis or Seven Sages (Rishis) viz. Bhrigu, Atri, Angiras, Vasishtha, Pulastya, Pulaha, and Kratu. The fact that the two front stars of the constellations point to the pole star is explained as the boon given to the boy sage Dhruva by Lord Vishnu. [43]
One of the few star groups mentioned in the Bible (Job 9:9; 38:32; – Orion and the Pleiades being others), Ursa Major was also pictured as a bear by the Jews. "The Bear" was translated as "Arcturus" in the Vulgate and it persisted in the King James Version of the Bible.
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:
In Shinto, the seven largest stars of Ursa Major belong to Ame-no-Minakanushi, the oldest and most powerful of all kami.
In South 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.
The Iroquois 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.
The Lakota people call the constellation Wičhákhiyuhapi, or "Great Bear".
The Wampanoag people (Algonquian) referred to Ursa Major as "maske", meaning "bear" according to Thomas Morton in The New England Canaan. [46]
The Wasco-Wishram Native Americans interpreted the constellation as five wolves and two bears that were left in the sky by Coyote. [47]
To Norse pagans, the Big Dipper was known as Óðins vagn, "Woden's wagon". Likewise Woden is poetically referred to by Kennings such as vagna verr 'guardian of the wagon' or vagna rúni 'confidant of the wagon' [48]
In the Finnish 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 a salmon weir. Ancient Finns believed the bear (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 the Sámi languages of Northern Europe, part of the constellation (i.e. the Big Dipper minus Dubhe and Merak, is identified as the bow of the great hunter Fávdna (the star Arcturus). In the main Sámi language, North Sámi, it is called Fávdnadávgi ("Fávdna's Bow") or simply dávggát ("the Bow"). The constellation features prominently in the Sámi anthem, which begins with the words Guhkkin 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 down Sarva, 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 hit Stella Polaris, known as Boahji ("the Rivet"), which would cause the sky to collapse and end the world. [49]
In Burmese, 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 a crustacean, such as prawn, shrimp, crab, lobster, etc.
In Javanese, it is known as "lintang jong", which means "the jong constellation". Likewise, in Malay it is called "bintang jong". [50]
In Theosophy, it is believed that the Seven Stars of the Pleiades focus the spiritual energy of the seven rays from the Galactic Logos to the Seven Stars of the Great Bear, then to Sirius, then to the Sun, then to the god of Earth (Sanat Kumara), and finally through the seven Masters of the Seven Rays to the human race. [51]
This section needs additional citations for verification .(April 2019) |
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.
Noted children's book author H. A. Rey, in his 1952 book The Stars: A New Way to See Them, ( ISBN 0-395-24830-2) had a different asterism 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 a polar bear. [52]
Ursa Major is also pictured as the Starry Plough, the Irish flag of Labour, adopted by James Connolly's Irish Citizen Army in 1916, which shows the constellation on a blue background; on the state flag of Alaska; and on the House of Bernadotte's variation of the coat of arms of Sweden. The seven stars on a red background of the flag of the Community of Madrid, Spain, may be the stars of the Plough asterism (or of Ursa Minor). The same can be said of the seven stars pictured in the bordure azure of the coat of arms of Madrid, capital of that country.
Alioth, also called Epsilon Ursae Majoris, is a star in the northern constellation of Ursa Major. The designation is Latinised from ε Ursae Majoris and abbreviated Epsilon UMa or ε UMa. Despite being designated "ε" (epsilon), it is the brightest star in the constellation and at magnitude 1.77 is the thirty-third brightest star in the sky.
Canes Venatici is one of the 88 constellations designated by the International Astronomical Union (IAU). It is a small northern constellation that was created by Johannes Hevelius in the 17th century. Its name is Latin for 'hunting dogs', and the constellation is often depicted in illustrations as representing the dogs of Boötes the Herdsman, a neighboring constellation.
Triangulum Australe is a small constellation in the far Southern Celestial Hemisphere. Its name is Latin for "the southern triangle", which distinguishes it from Triangulum in the northern sky and is derived from the acute, almost equilateral pattern of its three brightest stars. It was first depicted on a celestial globe as Triangulus Antarcticus by Petrus Plancius in 1589, and later with more accuracy and its current name by Johann Bayer in his 1603 Uranometria. The French explorer and astronomer Nicolas Louis de Lacaille charted and gave the brighter stars their Bayer designations in 1756.
Ursa Minor, also known as the Little Bear, is a constellation located in the far northern sky. As with the Great Bear, the tail of the Little Bear may also be seen as the handle of a ladle, hence the North American name, Little Dipper: seven stars with four in its bowl like its partner the Big Dipper. Ursa Minor was one of the 48 constellations listed by the 2nd-century astronomer Ptolemy, and remains one of the 88 modern constellations. Ursa Minor has traditionally been important for navigation, particularly by mariners, because of Polaris being the north pole star.
Virgo is one of the constellations of the zodiac. Its name is Latin for maiden, and its old astronomical symbol is . Between Leo to the west and Libra to the east, it is the second-largest constellation in the sky and the largest constellation in the zodiac. The ecliptic intersects the celestial equator within this constellation and Pisces. Underlying these technical two definitions, the sun passes directly overhead of the equator, within this constellation, at the September equinox. Virgo can be easily found through its brightest star, Spica.
Lynx is a constellation named after the animal, usually observed in the Northern Celestial Hemisphere. The constellation was introduced in the late 17th century by Johannes Hevelius. It is a faint constellation, with its brightest stars forming a zigzag line. The orange giant Alpha Lyncis is the brightest star in the constellation, and the semiregular variable star Y Lyncis is a target for amateur astronomers. Six star systems have been found to contain planets. Those of 6 Lyncis and HD 75898 were discovered by the Doppler method; those of XO-2, XO-4, XO-5 and WASP-13 were observed as they passed in front of the host star.
Kochab, Bayer designation Beta Ursae Minoris, is the brightest star in the bowl of the Little Dipper asterism, and only slightly fainter than Polaris, the northern pole star and brightest star in Ursa Minor. Kochab is 16 degrees from Polaris and has an apparent visual magnitude of 2.08. The distance to this star from the Sun can be deduced from the parallax measurements made during the Hipparcos mission, yielding a value of 130.9 light-years.
Phecda, also called Gamma Ursae Majoris, is a star in the constellation of Ursa Major. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. Based upon parallax measurements with the Hipparcos astrometry satellite, it is located at distance of around 83.2 light-years from the Sun.
An asterism is an observed pattern or group of stars in the sky. Asterisms can be any identified pattern or group of stars, and therefore are a more general concept than the 88 formally defined constellations. Constellations are based on asterisms, but unlike asterisms, constellations outline and today completely divide the sky and all its celestial objects into regions around their central asterisms. For example, the asterism known as the Big Dipper comprises the seven brightest stars in the constellation Ursa Major. Another is the asterism of the Southern Cross, within the constellation of Crux.
Dubhe, also called Alpha Ursae Majoris, Latinised from α Ursae Majoris, is, despite being designated "α" (alpha), the second-brightest object in the northern constellation of Ursa Major. This prominent asterism is known as the Big Dipper, the Plough, and the Great Bear. Alpha Ursae Majoris is the northern of the 'pointers', the second being Beta Ursae Majoris, or 'Merak' – this pair of stars point towards Polaris, the North Star.
Merak, also called Beta Ursae Majoris, is a star in the northern constellation of Ursa Major.
The Ursa Major Moving Group, also known as Collinder 285 and the Ursa Major association, is the closest stellar moving group – a set of stars with common velocities in space and thought to have a common origin in space and time. In the case of the Ursa Major group, all the stars formed about 300 million years ago. Its core is located roughly 80 light years away and part of the Local Bubble. It is rich in bright stars including most of the stars of the Big Dipper.
Alkaid, also called Eta Ursae Majoris, is a star in the constellation of Ursa Major. It is the most eastern (leftmost) star in the Big Dipper asterism. However, unlike most stars of the Big Dipper, it is not a member of the Ursa Major moving group. With an apparent visual magnitude of +1.86, it is the third-brightest star in the constellation and one of the brightest stars in the night sky.
Alcor is a binary star system in the constellation of Ursa Major. It is the fainter companion of Mizar, the two stars forming a naked eye double in the handle of the Big Dipper asterism in Ursa Major. The two lie about 83 light-years away from the Sun, as measured by the Hipparcos astrometry satellite.
Mizar is a second-magnitude star in the handle of the Big Dipper asterism in the constellation of Ursa Major. It has the Bayer designation ζ Ursae Majoris. It forms a well-known naked eye double star with the fainter star Alcor, and is itself a quadruple star system. The Mizar and Alcor system lies about 83 light-years away from the Sun, as measured by the Hipparcos astrometry satellite, and is part of the Ursa Major Moving Group.
Megrez, also called Delta Ursae Majoris, is a star in the northern constellation of Ursa Major. With an apparent magnitude of +3.3, it is the dimmest of the seven stars in the Big Dipper asterism. Parallax measurements yield a distance estimate of 80.5 light-years from the Sun.
Chi Ursae Majoris or χ Ursae Majoris, formally named Taiyangshou, is a single star in the northern circumpolar constellation of Ursa Major. The star has an orange hue and is visible to the naked eye at night with an apparent visual magnitude of 3.72. It is located at a distance of approximately 198 light-years from the Sun based on parallax, but is drifting closer with a radial velocity of −9 km/s.
4 Ursae Majoris (sometimes abbreviated 4 UMa) is the Flamsteed designation of a star in the northern circumpolar constellation of Ursa Major. It also bears the Bayer designation of Pi2 Ursae Majoris (Pi2 UMa, π2 Ursae Majoris, π2 UMa) and is traditionally named Muscida. With an apparent visual magnitude of +4.6, this star is visible from suburban or darker skies based upon the Bortle Dark-Sky Scale. From parallax measurements made during the Hipparcos mission, this star is at a distance of 256 light-years (78 parsecs) from Earth. As of 2011, one extrasolar planet has been confirmed to be orbiting the star.
Mizar and Alcor are two stars forming a naked eye double in the handle of the Big Dipper asterism in the constellation of Ursa Major. Their magnitudes are 2.2 and 3.9, and the pair can easily be seen without the aid of a telescope. Mizar's star is not a double star, but a four-star binary system located in the constellation Ursa Major. This system consists of two pairs of double stars that are gravitationally bound to each other. Mizar is the second star from the end of the Big Dipper's handle, and Alcor its fainter companion. The traditional name Mizar derives from the Arabic المئزر or miʼzar, meaning "apron; wrapper, covering, cover". Alcor was originally the Arabic سها or Suhā/Sohā, meaning either the "forgotten" or "neglected" one; notable as a faintly perceptible companion of Mizar. The ancient Persians and the Bedouins used distinguishing Mizar and Alcor as a test of vision.
The Big Dipper or the Plough is a large asterism consisting of seven bright stars of the constellation Ursa Major; six of them are of second magnitude and one, Megrez (δ), of third magnitude. Four define a "bowl" or "body" and three define a "handle" or "head". It is recognized as a distinct grouping in many cultures. The North Star (Polaris), the current northern pole star and the tip of the handle of the Little Dipper, can be located by extending an imaginary line through the front two stars of the asterism, Merak (β) and Dubhe (α). This makes it useful in celestial navigation.
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.