Kepler’s First and Second Laws

According to Kepler’s first law, every planet travels around the Sun along an elliptical orbit with the Sun at one focus. According to his second law, the line joining the planet and the Sun sweeps out equal areas (the burgundy-colored regions in the figure) in equal intervals of time (time from A to B equals time from C to D). Note: This drawing shows a highly elliptical orbit, with e = 0.74. Even though this is a much greater eccentricity than that of any planet in the solar system, the concept still applies to all planets and other orbiting bodies.