Map of the Universe
Castor
Star · Sextuple star system in Gemini
About Castor
Castor is about 50.87 light-years from the Sun, so the light we see from it left about 50.87 years ago.
At apparent magnitude 1.58 it can be seen with the naked eye from a dark site.
It gives out 49.4 times as much light as the Sun.
The map lists it as a star and shows it among the stars around the Sun, drawn on the plane of the Milky Way.
Key numbers
| Distance | 50.87 light-years (15.60 pc) |
|---|---|
| Spectral type | A2Vm |
| Apparent magnitude | 1.58 |
| Absolute magnitude | 0.61 |
| Luminosity | 49.4 × the Sun |
| Constellation | Gem |
Where it is
Its place in the universe, from the inside out: Solar neighbourhood › Local Bubble › Orion–Cygnus Arm (Local Arm) › Milky Way › Local Group › Virgo Supercluster › Laniakea Supercluster › Observable universe.
Zoom out to see it in context: 100 light-years, a view about 220 light-years across.
From Wikipedia
Castor is the second-brightest object in the zodiac constellation of Gemini. It has the Bayer designation α Geminorum, which is Latinised to Alpha Geminorum and abbreviated Alpha Gem or α Gem. With an apparent visual magnitude of 1.58, it is one of the brightest stars in the night sky.
Excerpt from the Wikipedia article Castor (star), licensed CC BY-SA 4.0.