Ba sic purpose of this lecture is to present on Johannes Kepler. Kepler’s laws are: Planets travel around the Sun in elliptical orbits with the Sun at one focus. A line from the planet to the Sun sweeps out equal areas in equal times. The square of a planet’s period in years and its distance cubed are proportional. Kepler started off with mystical ideas, and ended up correctly describing the motions of the planets.