Castor
Blue-white six-star system · Alpha Geminorum
A single point of light that is actually six stars
Castor looks like one star to the eye but is really a gravitationally bound system of six stars arranged as three close pairs. It is the second-brightest star in Gemini, marking one of the Twins' heads, and is slightly fainter than its golden neighbor Pollux.
Illustration generated from temperature, not a photograph
2.1 ☉
mass (the Sun = 1)
9,900 K
surface · white star
2 R☉
radius (the Sun = 1)
49 ly
from Earth
1.6
apparent magnitude
Its light has been travelling 49 years to reach us, so you see Castor as it was 49 years ago.
Source · View on Wikidata
It lives in
Milky Way
Barred spiral galaxy.
Other notable stars in Milky Way
Eta CarinaeLuminous blue variableAlnilamBlue supergiantVY Canis MajorisRed hypergiantAlnitakHot blue supergiantDenebBlue-white supergiantMintakaHot blue giant multiple star
Worlds in the same direction on the sky→