GEMINI (The Twins, i.e., Castor and Pollux), in astronomy, the third sign in the zodiac, denoted by the symbol II. By the Egyptians this constellation was symbolized as a couple of young kids; the Greeks altered this symbol to two children, variously said to be Castor and Pollux, Hercules and Apollo, or Triptolemus and Iasion; the Arabians used the symbol of a pair of peacocks. Castor is a double star with a separation of nearly 6" easily resolved with small telescopes ; the period of revolution of the two components is 35o years. Each of these visual components is a spectroscopic binary, the periods being 9.2 days and 2.9 days respectively. Another interesting star is Geminorum, which is variable in a period of 10.15 days; it belongs to the Cepheid class of variables.