PHYS 125 Astronomy: The Solar System This is the first semester of a two-part astronomy course, though each can be taken independently. It begins with an investigation of how the motions of the Earth affect what we see in the day and night skies. Then it will explore the planets, moons, and other objects of our Solar System. Currently, astronomers are discovering new planets around other stars monthly. This class will end with an investigation of these strange new exoplanet systems and the origin and fate of our own Solar System.