Figure 1: Illustration of Kepler's three laws with two planetary orbits. (1) The orbits are ellipses, with focal points ƒ 1 and ƒ 2 for the first planet and ƒ 1 and &>. (2) The two shaded sectors A 1 and A 2 have the same surface area and the time for planet 1 to cover segment A 1 is equal to the time to cover segment A 2. (3) The total orbit times for planet 1 and planet 2 have a ratio a 13/2 : a 23/2.
Penggambaran Hukum Gerakan Planet Kepler