Lecture summary, written by a student. The focus of this class was to continue the previous lecture discussion on radial velocities. The lecture introduced students to radial velocity curves, specifically how to read and understand their key features and use those to derive planet mass. Lecture began with a review of the derivation of planet mass using the equation for an elliptical orbit in the plane of the motion of orbit, finding planet motion in the direct line of sight, and then using Kepler?s second law of motion to calculate the planet mass.