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.