Kepler’s Second Law of Planetary Motion

Johannes Kepler discovered that planets do not move around the Sun at a constant speed. Instead, a planet travels faster when it is closer to the Sun and slower when it is farther away. Kepler’s Second Law states that an imaginary line joining a planet to the Sun sweeps out equal areas in equal intervals of time. This simulation allows you to investigate this law by creating sectors that represent the area swept out during a chosen time interval. By comparing sectors at different points in the orbit, you can see that equal time intervals produce equal areas, even though the planet’s speed changes continuously along its elliptical path.