- Stars with a name
- Castor B
Castor B
α Geminorum
Castor B is a white star, in the constellation Gemini. The light you see from it tonight left it around 1974.
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.
Visible to the naked eye away from the brightest lights. Apparent magnitude 2.85.
What it’s like
It gives off 16 times as much light as the Sun.
Its surface temperature is about 8,300 degrees Celsius.
It is 51.6 light years away: 488 trillion kilometres.
It is the star of people born around 1974: the light that left it then is reaching Earth now.