Science & history · Star guide
Capella, two giant stars in one point of light
Capella is the brightest star in Auriga, the Charioteer, and the first-magnitude star nearest the north celestial pole. What looks like one yellowish star is two giant stars circling each other every 104 days.
About this picture
NASA/Goddard Space Flight Center Scientific Visualization Studio. Gaia DR2: ESA/Gaia/DPAC. Constellation figures based on those developed for the IAU by Alan MacRobert of Sky and Telescope magazine (Roger Sinnott and Rick Fienberg). NASA's page (opens in a new tab).
The map is a composite of 1.7 billion catalogued stars, not a photograph from one place: it shows stars far too faint for the eye, and no weather, Moon or city light. It is drawn here in this chart's projection, with each star where it was in 2000; the fastest-moving bright star has shifted about a minute of arc since, far less than a pixel here.
How to spot it: Yellowish and brilliant: the first-magnitude star nearest the north celestial pole. Source (opens in a new tab)
Two giants in one point
What looks like one yellowish star is two giant stars circling each other every 104 days.
Jim Kaler (opens in a new tab) explains that Capella is a pair of similar giant stars, classes G8 and G0, so close together that separating them has taken interferometry and the Hubble Space Telescope. They go round each other in 104 days in a nearly circular orbit, 0.72 astronomical units apart.
Kaler's figures (opens in a new tab) for the pair: surfaces of about 4,900 and 5,700 kelvin, luminosities of 93 and 64 Suns, radii of 13.6 and 8.3 Suns, and masses near 3.0 and 2.5 Suns. Both were once hotter stars of class B, and the more massive one has moved further along its life, as the more massive star of a pair should.
ESA's list (opens in a new tab) ranks their combined light sixth among all stars and gives the distance as 42 light-years; Kaler (opens in a new tab) uses 43.
Sources for this section Jim Kaler, Capella, STARS (University of Illinois) (opens in a new tab); ESA, Hipparcos: The 50 Brightest Stars (opens in a new tab)
The She-Goat and her Kids
Capella means “the She-Goat”, and a little triangle beside her is called the Kids.
The name means “the She-Goat” (opens in a new tab), from Roman times. Capella is the alpha star of Auriga, the Charioteer, which Kaler describes as a prominent irregular pentagon of stars.
Just south of Capella, a thin triangle of fainter stars (opens in a new tab) is an asterism called the Kids, made of epsilon, zeta and eta Aurigae. Two of them carry IAU names that keep the story: Almaaz and Haedus (opens in a new tab), the latter Latin for a young goat.
Keep in mind “Kids” is an asterism, a named pattern inside a constellation, not a constellation of its own. Constellations and asterisms.
Sources for this section Jim Kaler, Capella, STARS (University of Illinois) (opens in a new tab); IAU Working Group on Star Names, IAU Catalog of Star Names (IAU-CSN) (opens in a new tab)
How to find it
On northern winter evenings Capella shines almost overhead; from the far south it barely clears the horizon.
In early winter evenings at mid-northern latitudes, Capella shines almost directly overhead (opens in a new tab). Kaler notes that it is the first-magnitude star closest to the north celestial pole.
By this site's calculation (opens in a new tab), it stands about 84° up in the north at its highest from 40°N, but only about 9° up in the north from 35°S, and it is highest at about 9 p.m. local time in mid-January.
Sources for this section Jim Kaler, Capella, STARS (University of Illinois) (opens in a new tab); Bright Star Catalogue, 5th Revised Ed. (Hoffleit & Warren 1991), as computed by this site's star engine (opens in a new tab)
Often confused with
Capella, Vega and Arcturus are close in brightness; colour and season separate them.
Kaler (opens in a new tab) groups Capella with Arcturus of spring and Vega of summer as three bright stars spread around the northern sky, all close to the same brightness: Arcturus orange, Vega white, Capella yellow-white in the middle of the temperature range and barely the faintest of the three.
In ESA's list (opens in a new tab) the three come fourth, fifth and sixth. In the same part of the winter sky is Taurus's brightest star, orange Aldebaran (opens in a new tab); against Capella's yellow-white, the colour is the clue. The Taurus guide shows where it sits.
Sources for this section Jim Kaler, Capella, STARS (University of Illinois) (opens in a new tab); ESA, Hipparcos: The 50 Brightest Stars (opens in a new tab); NASA Science, What's Up: December 2024 (opens in a new tab)
Where on Earth, and when
It rises from anywhere north of about 44°S.
North of about 44°N, it never sets.
It climbs at least 20° high, the finder's threshold for a suggestion, from anywhere north of about 24°S.
It is highest in the evening sky, at about 9 p.m. local time, in mid-January, from either hemisphere, wherever it rises. With daylight saving time, that is nearer 10 p.m. on the clock.
Worked out by this site from the Bright Star Catalogue, for a flat, clear horizon. Hills, buildings, haze and city light all cut into this; the air also lifts objects near the horizon by about half a degree. For your own place and night, use the sky finder.
Sources
- Astronomy Jim Kaler, Capella, STARS (University of Illinois) (opens in a new tab) for the two giants, the name, the Kids and where to look · checked 27 September 2026
- Astronomy ESA, Hipparcos: The 50 Brightest Stars (opens in a new tab) for rank and distance · checked 27 September 2026
- Astronomy IAU Working Group on Star Names, IAU Catalog of Star Names (IAU-CSN) (opens in a new tab) for the names Almaaz and Haedus · checked 2 October 2026
- Astronomy NASA Science, What's Up: December 2024 (opens in a new tab) for Aldebaran's colour · checked 27 September 2026
- Astronomy Bright Star Catalogue, 5th Revised Ed. (Hoffleit & Warren 1991), as computed by this site's star engine (opens in a new tab) for its height from 40°N and 35°S, and best month
