The Sun & Polaris
One is the quiet, middle-aged star that lights every day of your life. The other is a pulsing supergiant, 433 light-years away, that only ever points north. Here’s how they actually compare.
Two very different kinds of star
The Sun is a G-type main-sequence star — stable, hydrogen-burning, unremarkable by design. Polaris (technically Polaris Aa, the dominant star in a triple system) is an evolved F-type supergiant: it has left the main sequence, swollen to dozens of times the Sun’s size, and now pulsates every 3.97 days as a classical Cepheid variable.
Sol
The North Star
Size, drawn to scale
Polaris has only about 2.7× the Sun’s mass, but nearly 40× its radius — its outer envelope has swollen enormously as it burns through the last stable chapters of its life.
Cross sections
Cut each star open and the difference in life stage becomes obvious. The Sun fuses hydrogen steadily across a large core. Polaris no longer fuses in its core at all — it burns hydrogen in a thin shell wrapped around an inert helium center, beneath a deep, unstable envelope that makes the whole star pulse in and out.
The Sun
Polaris Aa
Full comparison
| Property | Sun | Polaris Aa |
|---|---|---|
| Spectral type | G2V | F7Ib |
| Evolutionary stage | Main sequence | Post-main-sequence supergiant |
| Radius | 1 R☉ | ~37.5 R☉ |
| Mass | 1 M☉ | ~5.4 M☉ |
| Surface temperature | 5,772 K | ~6,015 K |
| Luminosity | 1 L☉ | ~2,500 L☉ |
| Absolute magnitude | +4.83 | −3.64 |
| Apparent magnitude (from Earth) | −26.74 | +1.98 |
| Distance from Earth | 8.3 light-min | ~433 light-yr |
| Variability | Stable | Cepheid variable, 3.97-day pulse |
Stellar magnitude calculator
Apparent magnitude (m) is how bright a star looks from Earth. Absolute magnitude (M) is how bright it would look from a standard distance of 10 parsecs. The two are linked by distance through the distance modulus. Pick what you want to solve for, fill in the other two fields, and the third updates automatically.