Cosmic Scale
Polaris
Yellow supergiant · 433 light-years
How big is Polaris?
Polaris is about 5.2 × 10⁷ km across.
See Polaris in 3D, at true scale
Polaris sits almost exactly above Earth's north pole, so it barely moves while the sky turns around it — which made it the navigator's star for centuries. It is not especially bright; it is simply in the right place.
At a glance
| Diameter | 5.2 × 10⁷ km |
|---|---|
| Mass | 1.07 × 10³¹ kg |
| Diameter compared with Earth | 4,090 × Earth |
| Distance | 433 light-years |
| Type | Yellow supergiant, pulsating |
| Brightness | 1,260 Suns |
| Companions | Two smaller stars |
Good to know
- It is a Cepheid variable: it swells and shrinks every four days, a type of star used to measure distances across the universe.
- Earth's axis wobbles over 26,000 years, so Polaris has not always been the pole star and will not stay one.
- It will be at its closest to true north around AD 2100.