Torque-Free Orbital Motion Distance-Dependent Orbital Speed Perihelion Velocity Aphelion Speed Aphelion Velocity Eccentricity and Areal Motion Mean Motion Orbital Position Areal Velocity Elliptical Orbit Geometry Elliptical Orbit Sun-Planet Line Orbital Time Intervals Aphelion Distance Equal Time Intervals Second Law of Kepler Perihelion Speed Keplerian Orbital Period Perihelion Distance Orbital Sector Radius Vector Orbital Speed Angular Momentum Radial and Transverse Velocity Constant Areal Velocity