Kepler's Law of Planetary Motion

Johanne Kepler (December 27, 1571 - November 15, 1630)

He was a German scientist who is largely remembered for his work in astronomy. He found employment as an assistant to Tycho Brahe and, upon Brahe's unexpected death, replaced him as imperial mathematician of Emperor Rudolph II.

Kepler's Laws of Planetary Motion

1. Law of Ellipses : All planets moves in elliptical orbits, with the Sun at one focus.
   
   
2. Law of equal areas in equal time : A line that connects a planet to the Sun sweeps out equal area in equal time.
   
3. Law of harmony : The time required for a planet to orbit the Sun, called its period, is proportional to half the long axis of the ellipse raised to the 3/2 power. The constant of proportionality is the same for all the planets.