Castor and Pollux Castor and Pollux Castor and Pollux (or in Greek, Polydeuces) were twin half-brothers in Greek and Roman mythology, known together as the Dioscuri. Their mother was Leda, but they had different fathers; Castor was the mortal son of Tyndareus, the king of Sparta, while Pollux was the divine son of Zeus, who seduced Leda in the guise of a swan. Though accounts of their birth are varied, they are sometimes said to have been born from an egg, along with their twin sisters Helen of Troy and Clytemnestra. In Latin the twins are also known as the Gemini (literally "twins")
Castor (star) YY Geminorum. Castor (star) Castor, also designated Alpha Geminorum (α Geminorum, abbreviated Alpha Gem, α Gem) is the second-brightest point of light in the constellation of Gemini and one of the brightest in the night sky. It appears singular to the naked eye, but it is actually a sextuple star system in three binary pairs made up of the stars Castor Aa, Castor Ab, Castor Ba, Castor Bb, Castor Ca, and Castor Cb. Although it has the Bayer designation "alpha", it is fainter than Beta Geminorum, Pollux. Castor was recorded as a double star in 1718 by James Pound. It