- 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 temperature is about 9,400 degrees Celsius.
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.