Celestial phenomena in ancient Mesopotamia was observed and interpreted as signs from the gods as well as physical phenomena. Relating the various ways the heavens were contemplated and understood, this study traces the emergence of personal astrology from the tradition of celestial divination and how astronomical methodology developed for horoscopes. Its importance lies in its treatment of Babylonian celestial sciences (celestial divination, horoscopy, and astronomy) as subjects relevant to the history of science and culture.