Clytemnestra produced four offspring from two eggs: Castor and Clytemnestra from one egg, and Helen and Polydeuces (Pollux) from the other. Therefore, Castor and Clytemnestra were fathered by Tyndareus, whereas Helen and Polydeuces were fathered by Zeus. Agamemnon and his brother Menelaus were in exile at the home of Tyndareus; in due time Agamemnon married Clytemnestra and Menelaus married Helen. In a late variation, Euripides's "Iphigenia at Aulis", Clytemnestra's first husband was Tantalus, King of Pisa; Agamemnon killed him and Clytemnestra's infant son, then made Clytemnestra his wife. In another version, her first husband was King of Lydia. The kings of
Greek mythology in popular culture elements tantalum and niobium are always found together in nature, and have been named after the King Tantalus and his daughter Niobe. The element promethium also draws its name from Greek mythology, as does titanium, which was named after the titans who in mythology were locked away far underground, which reflected the difficulty of extracting titanium from ore. The U.S. Apollo Space Program to take astronauts to the moon, was named after Apollo, based the god's ability as an archer to hit his target and being the god of light and knowledge. Oceanographer Jacques-Yves Cousteau named his research ship, a