Kepler's Laws
These three laws of planetary motion were discovered by the German astronomer Johannes Kepler. His three laws later formed one of the most important parts of Sir Isaac Newton's discovery of universal gravitation. The three laws are as follows:
- Every planet follows an oval-shaped path, or orbit, around the sun, called an ellipse. The sun is located at the focus of one elliptical orbit.
- An imaginary line from the center of the sun to the center of a planets sweeps out the same area in a given time. This means that planets move faster when they are closer.
- The time is taken by a planet to make one complete tip around the sun is its period. The squares of the periods of two planets are proportional to the cubes of their mean distances from the sun.
