Today I learned about Johannes Kepler and his three laws.  He was a astronomer and lived from 1571-1630 and discovered these laws that are called "The Laws of Planetary Motion".  Johannes discovered that the planet move in an elliptical orbit around the sun. Johannes also discovered that planets move faster in some areas of its elliptical orbit than other areas and cover the same amount of area in the same amount of time. The last law is that the closer to the sun the planet is the less time it takes to orbit the sun.
Also, Kepler also discovered that planets such as Mars have retrograde motion. This is when planets move opposite of their direction. These retrogrades cause a motion called epicycles where planets move in a circular motion before continuing on there elliptical orbit.