- Stars with a name
- Castor
Castor
α Geminorum
Castor is a white star, in the constellation Gemini. The light you see from it tonight left it around 1975.
Where to find it
From mid-northern latitudes, such as New York, Rome or Tokyo, it is best seen in the evening sky in January, February, March, April, and December.
Bright enough to see even from a city. Apparent magnitude 1.58.
What it’s like
It gives off 49 times as much light as the Sun.
Its surface is at about 9,700 degrees.
It is 50.9 light years away: 481 trillion kilometres.
It is the star of people born around 1975: the light that left it then is reaching Earth now.