... This is made evident in two ways: by calculating the ratio of greatest and smallest orbital velocities (in the lesson plan, not given in "Stargazers"), and by invoking the concept of energy. ... Kepler's Second Law Skepl2nd.htm . ... 12a. "More about Kepler's Second Law Skepl2A.htm . ... Get an intuitive understanding for the way orbital velocities vary along each orbit, according to Kepler's second law. Get a first exposure to the concepts of "potential energy" and "kinetic energy." ...