Science & history · Constellation guide
Ursa Major, the Great Bear
Ursa Major, the Great Bear, is the third-largest constellation. Its seven brightest stars, the Big Dipper or Plough, form only the bear's back and tail; the rest of the animal is made of fainter stars.
About this picture
NASA/Goddard Space Flight Center Scientific Visualization Studio. Gaia DR2: ESA/Gaia/DPAC. Constellation figures based on those developed for the IAU by Alan MacRobert of Sky and Telescope magazine (Roger Sinnott and Rick Fienberg). NASA's page (opens in a new tab).
The map is a composite of 1.7 billion catalogued stars, not a photograph from one place: it shows stars far too faint for the eye, and no weather, Moon or city light. It is drawn here in this chart's projection, with each star where it was in 2000; the fastest-moving bright star has shifted about a minute of arc since, far less than a pixel here.
How to spot it: The Big Dipper's seven stars are the bear's back and tail. Source (opens in a new tab)
A bear with a dipper inside
The Big Dipper is only the bear's rump and tail; the whole constellation is much bigger and fainter.
Ian Ridpath (opens in a new tab) calls the seven stars of the Plough or Big Dipper the most familiar star pattern in the whole sky. They are only part of the bear, its rump and long tail; the rest of the animal is made of fainter stars, and the whole constellation is the third largest of the 88.
The Dipper on its own is an asterism, a recognised pattern that is not a constellation. The IAU (opens in a new tab) uses it as its example, noting that the same seven stars are the Plough in Europe, the Big Dipper in America and the Northern Dipper in Chinese tradition. The Big Dipper has its own guide.
Sources for this section Ian Ridpath, Star Tales: Ursa Major (opens in a new tab); International Astronomical Union, The Constellations (opens in a new tab)
How to find it
From mid-northern latitudes the bear never sets; from far enough south it never rises.
By this site's calculation (opens in a new tab), the bear's middle stands about 75° up in the north at its highest from 40°N and is highest at about 9 p.m. local time in mid-April. The computed block further down gives the latitudes where it never sets and where it never rises.
Homer already knew the first fact: he wrote of the Great Bear that never bathes in the sea (opens in a new tab), meaning that from Greece it never dipped below the horizon.
How to see it Use it as a signpost. The two stars at the end of the Dipper's bowl point to Polaris (opens in a new tab), which belongs to Ursa Minor, not to this bear; the curve of the handle arcs to Arcturus (opens in a new tab).
Sources for this section Bright Star Catalogue, 5th Revised Ed. (Hoffleit & Warren 1991), as computed by this site's star engine (opens in a new tab); Ian Ridpath, Star Tales: Ursa Major (opens in a new tab); Preston Dyches, What is the North Star and How Do You Find It?, NASA Science (2021, updated 2024) (opens in a new tab); NASA Science, What's Up: September 2021 (opens in a new tab)
Names for the north
Bear, wagon, plough and seven oxen: the same stars have carried many names.
According to Hyginus (opens in a new tab), the Romans called the Great Bear Septentrio, “seven plough oxen”, though in older times only two stars were oxen and the other five a wagon. Ridpath adds that the word septentrional was commonly used in Latin to mean “north”.
Germanicus Caesar, early in the first century, seems to have been the first to call the bears ploughs (opens in a new tab), because, he wrote, the shape of a plough is closest to the shape of their stars. In 1524 Petrus Apianus drew Ursa Major as three horses pulling a cart.
Sources for this section Ian Ridpath, Star Tales: Ursa Major (opens in a new tab)
A galaxy for binoculars
Messier 81, a spiral galaxy 11.6 million light-years away, is within reach of binoculars.
Messier 81 (opens in a new tab) sits in Ursa Major, 11.6 million light-years away, at magnitude 6.9. Through binoculars it is a faint patch of light sharing the field of view with its neighbour M82; a small telescope shows its core.
Nearly every star you see at night (opens in a new tab) is in our own Galaxy, including all the bear's. M81 is a separate galaxy that happens to lie in the same direction.
How to see it NASA suggests April (opens in a new tab) as the best time to look for it; from the Northern Hemisphere the bear is then high in the evening sky.
Sources for this section NASA Hubble, Messier 81 (opens in a new tab); Kat Troche (Astronomical Society of the Pacific), Catch Andromeda Rising!, NASA Night Sky Network (2024) (opens in a new tab)
Where on Earth, and when
The whole key pattern rises from anywhere north of about 28°S.
South of about 49°S, none of it rises.
North of about 49°N, the whole key pattern never sets.
Its middle climbs at least 20° high, the finder's threshold for a suggestion, from anywhere north of about 15°S.
It is highest in the evening sky, at about 9 p.m. local time, in mid-April, from either hemisphere, wherever it rises. With daylight saving time, that is nearer 10 p.m. on the clock.
Worked out by this site from the Bright Star Catalogue, for a flat, clear horizon. Hills, buildings, haze and city light all cut into this; the air also lifts objects near the horizon by about half a degree. For your own place and night, use the sky finder.
Sources
- History Ian Ridpath, Star Tales: Ursa Major (opens in a new tab) for the figure, its size, its ancient names and Homer · checked 27 September 2026
- Astronomy International Astronomical Union, The Constellations (opens in a new tab) for the Dipper as an asterism and its names · checked 27 September 2026
- Astronomy Preston Dyches, What is the North Star and How Do You Find It?, NASA Science (2021, updated 2024) (opens in a new tab) for the pointers to Polaris · checked 27 September 2026
- Astronomy NASA Science, What's Up: September 2021 (opens in a new tab) for arc to Arcturus · checked 27 September 2026
- Astronomy NASA Hubble, Messier 81 (opens in a new tab) for Messier 81 · checked 27 September 2026
- Astronomy Bright Star Catalogue, 5th Revised Ed. (Hoffleit & Warren 1991), as computed by this site's star engine (opens in a new tab) for its height from 40°N and best month
