Houjun Liu

Kepler's Laws of Planetary Motion

  1. Orbits of planetary bodies are ellipses with the sun at one of the two foci
  2. Drawing a line from the sun to the orbiting body, they would sweep out equal areas
  3. Planets that are closer to the sun have much shorter periods than that
    • Squares of the periods of the planets is equal to the cubes of the distance from the planet to the sun