Capella Star Facts
Capella star
Capella appears as the sixth brightest star in the night sky.
  • Capella is 42 light years from Earth and can be found in the constellation of Auriga.
  • Although Capella appears as a single star in the night sky it is actually a pair of binary stars.
  • Binary stars are simply two stars which orbit around each other, around half of all stars in our galaxy are part of a binary or multiple star system.
  • Capella is actually a four star system consisting of the bright binary pair Capella A and B, which are orbited by a distant pair of red dwarfs.
  • Capella A and B orbit each other approximately every 100 days at a distance of around 62,000 miles (100,000 km) .
  • Both Capella A and B are around 80 times more luminous than our sun.
  • Capella A and B are post main sequence stars, meaning they have exhausted the supply of hydrogen in their core and have expanded to around 5 times their original size.
  • Over the next few million years both Capella A and B will become red giants, expanding to many hundreds of times their original size.
capella system
Artist's impression of the binary stars as viewed from a hypothetical orbiting body.
Capella Radius
Capella A and B are both giant stars with a radius larger than that of the sun. Capella A is the largest of the two with a radius around 12 times that of the sun, 5.2 million miles (8.4 million km). Capella B has a radius of 3.9 million miles (6.3 million km) which is around 9 times larger than the radius of the sun.
Capella Mass
Both Capella A and B have a similar mass of around 2.6 to 2.7 of that of the sun.
Capella Temperature
Capella A and B have surface temperatures similar to our sun, the smaller Capella B has the hottest temperatures, estimated to be around 5,700C (10,000F), while Capella A has estimated surface temperatures of around 4,900C (8,900F).
Capella Statistics

Also Known As: Alpha Aurigae

Distance From Earth: 42 light years
Constellation: Auriga

Capella A Star Type: G class giant star
Capella B Star Type: G class giant star

Capella A Mass: 2.7 x Sun
Capella B Mass: 2.5 x Sun

Capella A Luminosity: 80 x Sun
Capella B Luminosity: 75 x Sun

Capella A Diameter: 10.4 million miles (16.8 million km) - 12 x Sun
Capella B Diameter: 7.8 million miles (12.6 million km) - 9 x Earth

Capella A Temperature: 4,900C (8,900F)
Capella B Temperature: 5,700C (10,000F)

Age: Both stars are around 500 million years old