Asteria — interactive night sky map
Castor (Alpha Geminorum) is a star in the constellation Gemini with an apparent magnitude of 1.58. It lies about 51 light-years from Earth. It is visible to the naked eye under dark skies.
It is best placed in the evening sky around January. It is visible from the whole northern hemisphere and from southern latitudes down to about 58°S. It is circumpolar (never sets) north of latitude 58°N.