In Greek mythology "golden-wreathed" Phoebe (Greek: Φοίβη Phoibe; pronounced /ˈfiːbiː/ in English), the feminine counterpart of the name Phoebus, was one of the original Titans, who were one set of sons and daughters of Uranus and Gaia. She was traditionally associated with the moon (see Selene), as in Michael Drayton's Endimion and Phœbe, (1595), the first extended treatment of the Endymion myth in English. Her consort was her brother Coeus, with whom she had two daughters, Leto, who bore Artemis and Apollo, and Asteria, a star-goddess who bore an only daughter Hekate.
Phoebe was a Titan, one of the original (that is, pre-classical) 14. She and Atlas were given dominion over the Moon, whose planetary power is that of Enchantment, and the second day of the week was their's. So, Phoebe is another Moon Goddess, her name means Bright Moon. She was the mother of Leto and Asteria through her brother Coeus(Intelligence). There was another Phoebe, a human priestess, who figures briefly in the story of Castor and Pollux. Anyway, it's Phoebe who was the grandmother of Artemis and Apollo, and her name became surnames for both twins.