Before today's class you should read Moons and Planets, pp. 47-52. These sections are about the historical development of celestial mechanics, Kepler's and Newton's Laws, and the general nature and measurement of orbits. We could spend the entire semester on these topics alone, so you should not feel that you will need to understand every subtle consequence of these sections. However, an accurate qualitative feeling for the nature of orbits and how they are changed is absolutely essential for what we will continue to do.
Before today's class you should read Moons and Planets, pp. 52-57. These sections are about the nature of orbits involving three or more "bodies" (as orbit people usually call objects in space). Since the solar system has an awful lot of "bodies", this material is important!.
The lab today is on Kepler's determination of the orbit of Mars.
Before today's class you should read Moons and Planets, pp. 57-65. These sections are about tidal forces and the basic nature of planetary rings.