Polaris is the North Star, a yellow-white giant that sits almost exactly above Earth’s North Pole, and the nearest pulsating Cepheid variable to us.
At a glance
| type | yellow-white giant (class F) |
|---|---|
| distance from the Sun | 432 light-years (133 pc) |
| its light left it | 432 years ago |
| luminosity | 1,260 × the Sun |
| radius | 37.5 × the Sun |
| surface temperature | 6,020 K |
| constellation | Ursa Minor (Little Bear) |
Read off the piece’s own catalogue, the same values it draws with.
About Polaris
Polaris lies close to the point in the sky above Earth’s rotation axis, so while every other star wheels around the pole through the night, Polaris barely moves. It is not especially bright, but its fixed place has made it a guide for navigators since long before the compass, found by following the two pointer stars of the Plough.
It is a Cepheid variable: it pulsates regularly, its brightness and size changing with a short period. Cepheids are key distance markers, so Polaris, the closest, matters well beyond its role as a pole star. It is a multiple system, with a close companion imaged by Hubble and a wider one seen in small telescopes.
Earth’s axis wobbles slowly, so the pole drifts. Thuban was the pole star long ago; Vega will be in the far future.
What you see in the piece
With HUMAN EYE on, face north and Polaris sits near the still centre of the turning sky, a modest yellow-white point at the end of the Little Bear’s tail.
Measured or modelled
Its distance is debated, with different methods disagreeing, and that uncertainty affects its luminosity and how it is used to calibrate Cepheid distances.
Questions
Is Polaris the brightest star in the sky?
No. Many stars are brighter; Polaris is famous because it sits almost exactly above Earth’s North Pole and so stays fixed while the sky turns.
How far away is Polaris?
Polaris is 432 light-years (133 pc) from the Sun, though its distance is still debated.