Conservative astronomer of Galileo's time, working without telescopes,ascribe held that earth ("geo,"as in " geography" or "geology") lay at the center of the solar system , orbited by botg the sun and the other planets. Indeed, to the casual observer, it seemed common sense that since the sun "rose" in the morning and "set" at night, it must have circled around the earth. Ancient authorities like Aristotle and the Roman astronmer Ptolemy had championed this viewpoint,and the notion also coincided with the Catholic Church's view of the universe,which placed mankind,God's principal creation, at the center of the cosmos.