Ursa Major is a constellation visible throughout the year in the northern hemisphere. Its name means "Great Bear" in Latin, and is derived from the legend of Callisto. Its seven brightest stars form a famous asterism known in North America as the Big Dipper, because the major stars can be seen to follow the rough outline of a large ladle, or dipper; this is recognized as a grouping of stars in many cultures throughout the eras. In the United Kingdom it is commonly known as the Plough, and was formerly called by the old name Charles's Wain ("wain" meaning "wagon") as it still is in Scandinavia, Karlavagnen. This common Germanic name originally meant the men's wagon (the churls' wagon) in contrast to the women's wagon (Ursa Minor). There is also a theory that it was named after Charlemagne. In Hindu astronomy, it is referred to as Sapta Rishi meaning "The Seven Sages".
The star Polaris, the Pole Star, can be found by measuring a line five times the angular distance between the two pointer stars Dubhe and Merak forming the end of the dipper cup, through those stars and up and away from the dipper. The dipper also points the way to other stars, for instance by sweeping down from the handle one reaches Arcturus (α Boötis) and Spica (α Virginis). A mnemonic for this is "Follow the arc to Arcturus, and speed on to Spica.".
In 1869, R. A. Proctor noticed that, except for Dubhe and Alkaid, the stars of the Big Dipper all have proper motions heading towards a common point in Sagittarius. This group, of which a few other members have been identified, formed an open cluster at some distant point in the past. Since then the sparse group has been scattered over a region about 30 by 18 light-years, centered some 75 light-years away, making it the closest cluster-like object. About 100 other stars, including Sirius, form a stream sharing approximately the same proper motion as the ex-cluster, but the exact relationship is unclear. Our solar system is in the outskirts of this stream, but is not a member, being about 40 times older.
In addition to the Big Dipper, another asterism comes from Arab culture – the "leaps of the gazelle", 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.
47 Ursae Majoris has a planetary system with three confirmed planets, 2.54 times and 0.76 times times the mass of Jupiter.
Several galaxies are found in Ursa Major, including the pair M81 (one of the brightest galaxies in the sky) and M82 above the bear's head, and M101, a beautiful spiral northwest of η Ursae Majoris. The constellation contains about 50 galaxies, most of which are below 10th magnitude.
Hera was not pleased with the placement of Callisto and Arcas in the sky, so she asked her nurse, Tethys, to help. Tethys, a marine goddess, cursed the constellations to forever circle the sky and never drop below the horizon, hence explaining why they are circumpolar. To observers above 41°N, these stars never seem to set.
In Hindu mythology, the Pole Star is Dhruva (the word means pole today) and there is a story behind him becoming a star.
