What kind of star is Polaris?
Polaris, catalogued as Alpha Ursae Minoris Aa (α UMi Aa), appears in the official constellation Ursa Minor. Its apparent visual magnitude is about 1.97; low-amplitude variable, while its estimated distance is about 447 light-years. Astronomers classify the object as F7 Ib classical Cepheid in a triple system. These labels describe temperature, luminosity class or system components; they should not be read as a claim that every naked-eye point is a single isolated star.
Polaris Aa is a supergiant that expands and contracts in a first-overtone Cepheid pulsation of roughly four days. Its brightness variation is modest to the eye but scientifically important because Cepheids connect pulsation period with intrinsic luminosity. A close companion orbits Aa and a wider F-type star, Polaris B, is visible telescopically. Measuring this benchmark is unusually difficult: its exceptional brightness challenges some detectors, its multiplicity affects astrometry, and published pulsation amplitudes have changed over time. Gaia-era work and orbital measurements continue to refine the system’s mass, evolutionary state and distance.
The coordinate pair RA 02h 31m 49.09s, Dec +89° 15′ 50.8″ fixes the object's direction on the celestial sphere for the J2000 reference epoch. Right ascension works like celestial longitude measured in hours, while declination works like latitude north or south of the celestial equator. Proper motion and improved measurements can refine catalogue positions, but these coordinates are sufficiently precise for a finder chart or planetarium search.
Polaris data at a glance
| Proper name | Polaris | Catalogue designation | Alpha Ursae Minoris Aa (α UMi Aa) |
|---|---|---|---|
| Constellation | Ursa Minor | Apparent magnitude | about 1.97; low-amplitude variable |
| Spectral or system type | F7 Ib classical Cepheid in a triple system | Estimated distance | about 447 light-years |
| Right ascension (J2000) | 02h 31m 49.09s | Declination (J2000) | +89° 15′ 50.8″ |
Values are rounded for an observer-friendly overview. Consult the linked SIMBAD record for component-level identifiers, bibliography, measurement provenance and newer catalogue values.
The name Polaris
Polaris is Latin for “polar star.” The IAU assigns the name to Alpha Ursae Minoris Aa, the classical Cepheid that dominates the system’s light.
Precession slowly changes the direction of Earth’s axis, so Polaris has not always been—and will not always remain—the closest bright pole star. Greek navigators used other northern patterns, while later European and Islamic traditions increasingly relied on this star. William Herschel identified its visible companion in 1780. In the twentieth century, Polaris’s Cepheid behaviour made it a calibration target as well as a navigational icon. The IAU standardized the component-specific name in 2016.
Modern professional catalogues retain identifiers such as the Bayer designation alongside a proper name. The International Astronomical Union standardizes which name belongs to which component—an important distinction for systems whose combined light looks like one star from Earth.
How to find Polaris
Extend the line from Merak through Dubhe about five times their separation to reach Polaris. Its altitude above a level northern horizon approximately equals the observer’s latitude. A small telescope can reveal the much fainter companion Polaris B under steady conditions.
Visible throughout the Northern Hemisphere; circumpolar from most northern locations and never rises south of the equator. Visibility on a particular night still depends on latitude, season, time, horizon obstructions, weather and local light pollution. Use the interactive atlas below to check the surrounding field before observing.
Observation checklist
- Use the two outer bowl stars of the Big Dipper, Merak and Dubhe, as pointers.
- Measure Polaris’s altitude with a simple clinometer for an approximate northern latitude.
- At 50–100×, look for Polaris B about 18 arcseconds from the brilliant primary.
- Long-exposure photographs centred here make every other star trail around the north celestial pole.
Interesting facts about Polaris
- Polaris is only about the 48th-brightest night-sky star, not the brightest.
- It lies less than one degree from the north celestial pole at present.
- Polaris Aa is a classical Cepheid with a pulsation period near four days.
- The system contains at least three stars.
- Vega and Thuban serve as pole-star analogues at other stages of Earth’s precession cycle.
Continue from Polaris into the night sky
Use the Ursa Minor constellation guide to place this star within its larger pattern. When you are ready to observe, compare dark-sky places, find a nearby observatory, or follow our practical guide to finding a star in the night sky. Symbolically registered names are kept separately in the searchable Star-Register catalogue.
Sources and further reading
Measurements are rounded for readability. Multiple systems, variable stars and distant supergiants can have component-specific or model-dependent values. Survey panels show photographic sky fields, not the physical surface of the star.