Aster › Space program › Polaris
Polaris
Position on the route: 152/181 · level needed 2180 · journey (Mk0 engine) 403.1 h
By the numbers
| Distance | ≈ 433 light-years |
|---|---|
| Type | Cepheid, ≈ 4 days |
| System | triple |
| North pole | about 0.7° away |
The story
Polaris (the North Star) lies within about 0.7° of the north celestial pole and has been used for navigation for centuries. It is about 430 light-years from the Sun: a bright supergiant and a Cepheid variable whose brightness pulses roughly every four days.
In fact a triple system: Hubble imaged its companions in 2006. The Cepheid period–luminosity relation is a cornerstone of measuring distances to galaxies. Because Earth’s axis wobbles, the pole star changes about every 26,000 years.
Missions
- Hubble (2006): the companions
- Gaia: distance measurement
Colony note
No surface; an orbital station only.
☠ A pulsating Cepheid star: no surface. An orbital station only.
What probes bring back
- About 433 light-years away: the bright star nearest the north celestial pole, used for navigation for centuries. A Cepheid: its brightness pulses every four days and it is one of the foundations of distance measurement.
- In fact a triple system whose companions Hubble imaged. Because Earth’s axis wobbles, the pole star changes every 26,000 years: Vega will be the North Star in about 11,700 years.