Ursa Major and the Big Dipper
Ursa Major is one of the 88 constellations, and it represents the great bear. It is highest in the sky at midnight around March 5, and its whole figure rises above the horizon from 90°N to 27°S.
Ursa Major at a glance
- Represents
- the great bear
- Highest at midnight
- March 5
- Highest at 9 pm
- April 19
- Seen whole from
- 90°N to 27°S
- Brightest star
- Alioth
- Stars in the figure
- 18 stars
- Origin
- Ptolemy's list, 2nd century
The Big Dipper
The Big Dipper is not a constellation of its own. It is an asterism: seven bright stars of Ursa Major, Dubhe, Merak, Phecda, Megrez, Alioth, Mizar and Alkaid, that form a bowl and a handle. In Britain and Ireland it is called the Plough.
Merak and Dubhe, the two stars at the end of the bowl, are known as the Pointers. They are 5.4° apart. Follow the line from Merak through Dubhe for about 5 times that distance, 29°, and you reach Polaris, the North Star.
The whole Big Dipper never sets north of 41°N, and it rises above the horizon everywhere north of 28°S.
When to see Ursa Major
Ursa Major is highest in the sky at midnight around March 5 and at 9 pm around April 19. Each month it is highest about two hours earlier than the month before.
The times are local solar time. Clocks on daylight saving time read about one hour later.
| Date | Highest at |
|---|---|
| January 15 | 3:10 a.m. |
| February 15 | 1:10 a.m. |
| March 15 | 11:20 p.m. |
| April 15 | 9:20 p.m. |
| May 15 | 7:20 p.m. |
| June 15 | 5:20 p.m. |
| July 15 | 3:20 p.m. |
| August 15 | 1:20 p.m. |
| September 15 | 11:10 a.m. |
| October 15 | 9:20 a.m. |
| November 15 | 7:10 a.m. |
| December 15 | 5:20 a.m. |
Where to look for Ursa Major
From the northern hemisphere
From 40°N, Ursa Major rises in the east and sets in the west. It is highest around midnight on March 5, 75° above the northern horizon.
From the southern hemisphere
From 35°S, only part of Ursa Major rises. Its center is highest around midnight on March 5, 0° above the northern horizon.
Brightest stars in Ursa Major
Ursa Major in myth and history
In Greek myth, the great bear is Callisto, a nymph whom Zeus loved. She was turned into a bear, and Zeus later placed her among the stars.
Ursa Major is one of the 48 constellations that the astronomer Ptolemy listed in the 2nd century.
Constellations next to Ursa Major
Find Ursa Major in your sky
Questions about Ursa Major
Ursa Major is highest in the sky at midnight around March 5 and at 9 pm around April 19. The weeks around those dates are the best time to look.
The whole figure of Ursa Major rises above the horizon from 90°N to 27°S, and at least part of it rises from 90°N to 49°S.
Alioth is the brightest star in Ursa Major, at magnitude 1.76.
Ursa Major represents the great bear. Ursa Major is one of the 48 constellations that the astronomer Ptolemy listed in the 2nd century.
No. The Big Dipper is an asterism, a pattern of seven bright stars in the constellation Ursa Major.