 In Greek mythology, Castor and Pollux (the two brightest stars in  the constellation Gemini) were the twin sons of Zeus by Leda. The  brothers fought together in the Trojan War (which, of course, was  fought in *Troy*). This is not their only connection to Troy, their  mother Leda was also the mother of Helen of Troy. Of the Castor and  Pollux of mythology, Pollux was immortal and Castor mortal. They  were allowed to spend alternating days together between the  underworld and Olympus because Zeus took pity on the pair and "gave"  Castor half of Polluxs immortality because they could not take the  separation of death.