What kind of star is Capella?
Capella, catalogued as Alpha Aurigae (α Aur), appears in the official constellation Auriga. Its apparent visual magnitude is 0.08, while its estimated distance is 42.9 light-years. Astronomers classify the object as G8 III + G0 III; two red-dwarf companions. 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.
Capella Aa and Ab are yellow giants with similar masses but different temperatures, rotation rates and evolutionary states. Their nearly circular 104-day orbit is too tight for ordinary visual separation, yet optical interferometers can reconstruct the pair and combine its sky motion with radial velocities to obtain three-dimensional orbits and precise masses. The cooler giant appears slightly fainter visually while emitting more energy across all wavelengths, a useful reminder that visible brightness is not bolometric luminosity. Farther away, Capella H and L form a pair of faint red dwarfs gravitationally linked to the giants, creating a hierarchical four-star system.
The coordinate pair RA 05h 16m 41.36s, Dec +45° 59′ 52.8″ 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.
Capella data at a glance
| Proper name | Capella | Catalogue designation | Alpha Aurigae (α Aur) |
|---|---|---|---|
| Constellation | Auriga | Apparent magnitude | 0.08 |
| Spectral or system type | G8 III + G0 III; two red-dwarf companions | Estimated distance | 42.9 light-years |
| Right ascension (J2000) | 05h 16m 41.36s | Declination (J2000) | +45° 59′ 52.8″ |
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 Capella
Latin for “little she-goat,” reflecting Auriga’s ancient depiction carrying the goat Amalthea.
Capella is Latin for little she-goat, associated in classical art with the goat carried by Auriga and often identified with Amalthea, nurse of the infant Zeus. Spectroscopic observations revealed the bright star’s duplicity in the late nineteenth century. During the twentieth century, long-baseline interferometers turned Capella into a calibration and imaging milestone because the components are bright and their orbit is measurable. These observations refined stellar masses and showed that two nearly equal-mass stars can occupy noticeably different stages of post-main-sequence evolution.
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 Capella
Find the conspicuous yellow-white star north of Orion and above Taurus during winter. It anchors Auriga’s pentagonal outline and remains visible throughout the year at high northern latitudes.
Best on northern winter evenings and circumpolar north of about 44° N. 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
- Find the bright yellow-white star north of Orion and Taurus on winter evenings.
- Trace the pentagon of Auriga; Capella occupies its northern corner and remains visible through strong urban glow.
- Do not expect to split the inner giants in a backyard telescope—their separation requires optical interferometry.
- From latitudes above roughly 44° N, revisit Capella year-round to follow its circumpolar path.
Interesting facts about Capella
- Capella appears single to the eye but is a four-star system arranged as two binary pairs.
- The bright inner pair consists of two yellow giants orbiting in about 104 days.
- A distant pair of faint red dwarfs accompanies the giant pair.
- Capella is the brightest star in Auriga and among the brightest in the night sky.
- Its Sun-like yellow colour is deceptive: both bright components are much larger evolved giants.
Continue from Capella into the night sky
Use the Auriga 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.