Johannes+Kepler

Kepler assumed that the earth orbited in an elliptical, which is an oval. He also thought that a planets speed varies according to the distance it is from the sun. In the early 1600’s Kepler observed planetary positions and developed 3 laws to describe them. The first law is, the path of every planet in motion around the sun forms an elliptical at one focus. The second law is, the speed of planets in their orbit varies so that a line joining it with the sun sweeps over equal areas at equal times. Later he developed a third law that had to do with, the distance between a planet, the sun, and the time it completes its orbit. Much later Isaac Newton proved the three laws mathematically.