Astronomy Study is a field of science that involves the study of celestial objects and phenomena in the universe. URANIA, with 6 letters, is the muse of astronomy in Greek mythology. EON, with 3 letters, is an indefinitely long period of time. Sagan, with 5 letters, is a famous astronomer and astrophysicist who popularized science through his books and television series. URSA, with 4 letters, is a constellation of stars in the northern sky. All of these terms are related to Astronomy Study, which is the study of the stars, planets, and other objects in the universe.