In the early 1600s, Johannes Kepler proposed three laws of planetary motion. Kepler was able to summarize the carefully collected data of Astronomer Tycho Brahe with three statements that described the motion of planets in a sun-centered solar system.
His laws that were developed back in the 1600's are still considered an accurate description of the motion of any planet and any satellite.
Kepler's laws are summarized here:
The path of the planets about the sun is elliptical in shape, with the center of the sun being located at one focus. (The Law of Ellipses)
An imaginary line drawn from the center of the sun to the center of the planet will sweep out equal areas in equal intervals of time. (The Law of Equal Areas)
The ratio of the squares of the periods of any two planets is equal to the ratio of the cubes of their average distances from the sun. (The Law of Harmonies)
Simulator courtesy of University of Nebraska-Lincoln