UMa · Ursae Majoris
Ursa Major Constellation
IAU constellation mapUMaUrsa Major (UMa) is one of the 88 constellations recognised by the International Astronomical Union. It covers 1280 square degrees of the northern sky in quadrant NQ2. Its brightest star is Alioth. The Latin genitive of the name is Ursae Majoris, used to form star names within the constellation. In Greek mythology, Ursa Major is associated with greek tradition. The IAU standardised all constellation boundaries in 1930.
Quick facts
- IAU name
- Ursa Major
- Abbreviation
- UMa
- Latin genitive
- Ursae Majoris
- Hemisphere
- northern
- Area
- 1,280 sq deg
- Brightest star
- Alioth
- Quadrant
- NQ2
- Family
- Ursa Major
- Mythology origin
- Greek
- Discovery era
- Ptolemy's 48 (Almagest, c. 150 CE)
Mythology
Ursa Major, the Great Bear, is one of the oldest and most universally recognised star patterns. The seven brightest stars form the asterism known as the Big Dipper, the Plough, or the Wagon. In Greek mythology the bear represents Callisto, a nymph who was a devoted hunting companion of Artemis. Zeus seduced her (in some accounts disguising himself as Artemis), and when the pregnancy was discovered, Artemis expelled Callisto from the huntresses. When Callisto's son Arcas was born and grew to manhood, the two nearly encountered each other in the forest; Zeus, fearing violence, transformed them both into bears and placed them in the sky — Callisto as Ursa Major and Arcas as Ursa Minor (or Bootes in some accounts). In Babylonian, Chinese, Native American, and many other astronomical traditions, the same seven stars also form some figure of importance, suggesting the pattern is among the earliest named by human cultures. The two end stars of the Dipper's bowl, Dubhe and Merak (the 'Pointers'), point toward Polaris, the North Star. At 1280 square degrees, Ursa Major is the third-largest constellation and contains the Whirlpool Galaxy (M51), one of the most photographed galaxies.
Sources: Aratus Phaenomena 26-44; Apollodorus Bibliotheca 3.8.2; Ovid Metamorphoses 2.401-507.
Overview
Ursa Major is one of the 88 constellations formally recognised by the International Astronomical Union (IAU). It occupies 1280 square degrees of sky in the northern hemisphere sky, best visible at latitudes between +90 and -60 degrees in March. The constellation belongs to the Ursa Major family of constellations. Its Latin genitive is Ursae Majoris, the form used when naming stars within the constellation — for example, the brightest star Alioth may appear in catalogues as Alpha Ursae Majoris or similar. The IAU standardised the boundaries of all 88 constellations in 1930 under the direction of Eugène Delporte, using straight lines of right ascension and declination to eliminate the ambiguities of earlier variable-boundary systems.
Notable stars
The brightest star in Ursa Major is Alioth. Individual stars within Ursa Major are conventionally named using Bayer designation — Greek letters followed by the Latin genitive of the constellation name (Ursae Majoris) — introduced by Johann Bayer in his 1603 star atlas Uranometria. Flamsteed numbers (numeric designators followed by Ursa Major) were added by John Flamsteed in his 1712 catalogue. Variable stars, double stars, and deep-sky objects within the Ursa Major boundary are catalogued by the IAU with the abbreviation UMa.
History and mythology
The figure of Ursa Major appears in the classical astronomical tradition. Ptolemy included this constellation in the Almagest (c. 150 CE), the definitive ancient catalogue of 48 constellations, which formed the foundation for Islamic, medieval European, and Renaissance astronomy. The constellation's figure and mythology were transmitted through works such as Aratus's Phaenomena, Eratosthenes's Catasterismi, and Hyginus's Astronomica. See the Mythology section above for the full narrative.
Sources & further reading (2)
- official-iau — accessed 2026-05-06
- encyclopedia — accessed 2026-05-06
Frequently asked questions
What does the name Ursa Major mean?
Ursa Major is the Latin name used by the IAU to designate this constellation. The name comes from classical Latin and Greek astronomical tradition. In star catalogues, stars within Ursa Major are designated using the genitive form of the name (e.g. Alpha Ursa Major or similar Latin genitive forms) — a naming convention introduced by Johann Bayer in his 1603 atlas Uranometria and still in use today.
How large is Ursa Major compared to other constellations?
Ursa Major covers 1280 square degrees of sky. The full sphere of the sky contains 41,253 square degrees, so Ursa Major occupies about 3.1% of the total sky. For comparison, the largest constellation is Hydra at 1303 square degrees; the smallest is Crux at 68 square degrees.
When and where is Ursa Major visible?
Ursa Major is primarily a northern hemisphere constellation, best seen from mid-northern latitudes. Southern hemisphere observers may see it low on the horizon depending on their latitude. The brightest star, Alioth, serves as the main visual anchor for locating the constellation. As with all constellations, the best viewing conditions are a dark sky away from artificial light pollution, with the constellation high enough above the horizon to minimise atmospheric absorption.
