Ursa Minor
What is Ursa Minor?
Constellations· All year (N) · Polaris at the handle tip. The Little Dipper, with Polaris at the end of its handle. The north celestial pole lies inside it, so through the night the rest of the sky appears to turn around this small constellation.
📍 Visible from where you are right now — computed in your browser
Stars of the figure
| Star | Magnitude |
|---|---|
| Polaris | 2.0 |
| Kochab | 2.1 |
The 2 brightest of the 9 stars used in the figure (9 lines). Lower magnitude means brighter.
Constellation basics
| Season | circumpolar — visible all year from mid-northern latitudes |
|---|---|
| Brightest star | Polaris (2.0) |
| How to find | extend the Big Dipper's pointer stars ×5 |
| Area rank | 56th of 88 |
Figures are representative approximations. Source: compiled from NASA and IAU public data.
Polaris swells every four days — and is really three stars
Polaris is a Cepheid variable, a star that swells and shrinks over about four days, changing slightly in brightness as it does, and it is the nearest such star to Earth. In the early twentieth century its brightness swung by about 0.1 magnitude. By the 1990s the swing had shrunk to 0.02, as if the pulsing were about to stop. Since then it has grown a little again, and why this happens is still unexplained.
Polaris is not a single star either. In 1780 William Herschel found a faint companion, Polaris B, which a small telescope can show separately. A third star, Polaris Ab, sits much closer and was known for a long time only from studies of the starlight. In 2006 the Hubble Space Telescope photographed it for the first time; it circles Polaris about once every 30 years. The star that stays fixed all night is really a family of three.
The constellation in depth
In Greek myth Ursa Minor is either a nymph who cared for the infant Zeus or Arcas, son of Callisto, who became the Great Bear. Phoenician sailors of the ancient Mediterranean found north by these stars, which is why it was also called the Phoenician star. Small as it is, it mattered greatly in the history of navigation.
Polaris, at the end of the handle, lies less than one degree from the north celestial pole, so it stays almost still all night. Kochab and Pherkad, at the bowl, are known as the Guardians of the Pole. Around 1500 BC Kochab was closer to the pole than Polaris was. Earth's axis slowly changes direction over about 26,000 years, so the star nearest the pole changes from age to age.
A line through Merak and Dubhe, the end stars of the Big Dipper's bowl, carried on about five times reaches Polaris. City skies show only Polaris and Kochab, but a dark site reveals the whole Little Dipper. The height of Polaris above the horizon equals the observer's latitude, and moving the observing site south in the Sky view shows Polaris sinking toward the horizon.
Frequently asked
- When can I see Ursa Minor?
- Ursa Minor is best seen in circumpolar — visible all year from mid-northern latitudes.
- How do I find Ursa Minor?
- To find Ursa Minor, look for extend the Big Dipper's pointer stars ×5.
- What is the brightest star in Ursa Minor?
- The brightest star in Ursa Minor is Polaris, at magnitude 2.
Related
Figures are representative approximations. Simulated positions use J2000 mean elements.