Urania is the Greek muse of astronomy, and her name is often used to refer to the science itself. EON is an immeasurably long period of time, which is often used to describe the age of the universe. Carl Sagan was an American astronomer, astrophysicist, cosmologist, and author who popularized science and astronomy. URSA is Latin for bear, and is used to refer to the constellation URSA Major, which is one of the most recognizable constellations in the night sky.