Why do Kepler's Laws work? This lecture discusses how Newton applied

his Three Laws of Motion and the Law of Universal Gravitation to the

problem of orbits. Newton generalized Kepler's laws to apply to any two

massive bodies orbiting around their common center of mass. We discuss

these new, generalized laws of orbital motion, introducing the families

of open and closed orbits, circular and escape velocity, center-of-mass,

conservation of angular momentum, and how orbital mechanics is used to

measure the masses of astronomical objects. Recorded 2006 Oct 17 in 100

Stillman Hall on the Columbus campus of The Ohio State University.