How do the planets move across the sky? This lecture discusses the
motions of the 5 naked-eye planets (Mercury, Venus, Mars, Jupiter, and
Saturn) as seen from the Earth. We introduce the major configurations
of the planets, and then discuss their apparent retrograde motions. The
apparent motions of the planets are far more complex than those of the
Sun, Moon, and stars, and present a great challenge to understand. The
centuries long effort to understand these motions was to give birth to
modern science. Recorded 2007 Oct 4 in 1000 McPherson Lab on the
Columbus campus of The Ohio State University.