α Gem. Magnitude 1.98, white. Comfortably visible to the naked eye from a suburban sky.
Astronomers call it α Gem — the Bayer designation, which reads as a Greek letter ranking its brightness within its constellation. Castor is the name people actually use.
Castor shines at magnitude 1.98, making it comfortably visible to the naked eye from a suburban sky. Its B−V colour index of 0.03 makes it white to the eye, corresponding to a surface temperature of around 8,000 K.
It sits at right ascension 7.58 hours and declination +31.9°. It sits well north on the sky and is comfortably placed for northern hemisphere observers.
SkyRef shows exactly where Castor is from your location right now — altitude, compass direction, and rise and set times.