Lecture 12: The Wanderers - Planetary Motions

How do the planets move across the sky? This lecture will review planetary motions, specifically the apparent motions of the five classical planets (Mercury, Venus, Mars, Jupiter, and Saturn) as seen from the Earth. We will discuss the classical division of the naked-eye planets into inferior (Mercury and Venus) and superior (Mars, Jupiter, and Saturn) planets, and describe their main configurations in the sky: conjunction, opposition, maximum elongation, and quadrature. We will then discuss retrograde motion, the apparent westward reversal of motion seen at opposition in the superior planets and inferior conjunction in inferior planets. The quest to describe the very complex motions of the planets marks the birth of science, and will be the central theme of next week's lectures. Recorded 2006 Oct 5 in 100 Stillman Hall on the Columbus campus of The Ohio State University.