Polaris vs Vega
Precession has handed the role of pole star back and forth between these two. Polaris holds it now, sitting at declination +89°, within a degree of the north celestial pole; Vega occupied the position some twelve thousand years ago and will do so again. In brightness they are not close. Vega shines at magnitude 0.03 against 1.97 for Polaris, near six times the light, largely because Vega lies 25.04 light-years away and Polaris 432.57 — a factor of seventeen. Intrinsically the order flips hard: Polaris carries an absolute magnitude of −3.64 to Vega's +0.60, making the F-type supergiant something like fifty times the more luminous star.
Property comparison
| Property | Polaris | Vega |
|---|---|---|
| Designation | 1Alp UMi | 3Alp Lyr |
| Constellation | N/A | Lyra |
| Spectral Class | Class F — F-type (Yellow-White) | Class A — A-type (White) |
| Apparent Magnitude | +1.97 | +0.03 |
| Absolute Magnitude | -3.64 | 0.60 |
| Distance | 433 ly | 25.0 ly |
| Mass | N/A | N/A |
| Radius | N/A | N/A |
| Temperature | N/A | N/A |
| Luminosity | N/A | N/A |
Full data for each star: Polaris · Vega
Key differences
Key Differences
- ◆ Polaris is an F-type Cepheid variable supergiant; Vega is a stable A-type main-sequence star.
- ◆ Polaris is 431 light-years away; Vega is much closer at 25 light-years.
- ◆ Polaris sits near the north celestial pole and has guided navigators for centuries; Vega was the pole star ~14,000 years ago.
- ◆ Vega served as the original zero-magnitude reference for the photometric system.
- ◆ Polaris pulsates in brightness; Vega has a debris disk suggesting a forming planetary system.
When to Observe
Polaris
Polaris never sets from the northern hemisphere. At declination +89° it is circumpolar for every northern latitude, holding an almost fixed altitude equal to the observer's latitude, and it is invisible south of the equator.
Vega
Vega culminates at midnight in late June and dominates summer evenings. Its declination of +38° makes it circumpolar above about 52°N and still accessible from the northern tropics of the southern hemisphere.