Alpha Geminorum is the brightest star in the constellation Gemini. It is also known by its traditional names, Castor and Alpha Geminorium. Castor is derived from the Greek mythological twins Castor and Pollux, who were placed in the sky as the constellation Gemini. Alpha Geminorium refers to the star's position as the brightest star in the constellation. Other synonyms for Alpha Geminorum include HD 60179, HR 2903, and HIP 36850, which are all designations used by different astronomical organizations. In addition, the star can also be referred to as Spica, which is another bright star in the constellation Virgo.