Since the time of the ancient Greek natural philosophers, there have been thousands of years of discoveries which have led to our present day understanding of the universe. We will consider, very briefly, the seminal work of the ancient Greeks and end at the stunning changes in Astronomy which occured in a span of just one hundred years or so in the seventeenth century. Appropriate to this course, most of what we cover will deal with the motion of the planets. Planetary astronomy was fairly well understood first by astronomers. Our understanding of stars, on the other hand, was very rudimentary even up to the mid-nineteenth century.We begin in the time of classical Greece, when the first attempts were made for a rational explanation of the sky. Humans of that time, for the most part, still believed in the central location of Earth. For them, it was a geocentric universe. In the time of the Renaissance, a Polish cleric by the name of Copernicus convinced himself that a simpler explanation had the Sun in the center of all things. Following Copernicus was Galileo, who used the observational proof of his telescope to show the truth of the heliocentric theory.