Johannes Kepler's work helped to explain the movement of the planets around the Sun. He was born on December 27, 1571 in Weil, Germany. He was a weak, sickly child born to poor parents who fought a lot. Kepler's father, Heinrich, didn't want to support his wife and children so when Johannes was only three his father left home. Heinrich hired himself out as a soldier and after a couple of years he left the family completely.

From the time that Johannes was a boy he wanted to study and become a Protestant clergyman. However his family was so poor that they couldn't pay for his education, but because Kepler was a good student he earned the scholarships he needed to take him through school. He went to the University of Tubingen in 1589 to study to become a clergyman.

Johannes studied other subjects, like mathematics, besides religion at the University, and he became impressed by the order and exactness of math. He believed that God must have used math when he designed the universe. By the end of his stay at the University Kepler decided to change his life's work from clergyman to astronomer. He felt that there were other ways he might serve God. He believed that being an astronomer and using math to study the motions of the planets was one way. So he became a math teacher and did astronomy research in his spare time. Also, by this time he accepted the Copernican theory that the earth is one of a group of planets that revolve around the sun.

Over the course of many years, Johannes Kepler developed several mathematical laws about planetary motion; three of which describe the speed and paths of planets around the sun. On top of this Kepler wrote books on astronomy in Latin. Three of the most important books were: Mysterium Cosmographicum (Cosmic Mysteries), Astronomia Nova (New Astronomy) and Harmonices Mundi (The Harmony of the Universe) in which all of his planetary motion laws are explained.

Kepler was appointed court mathematician in 1601 by the Holy Roman Emperor Rudolph II. Kepler gained fame as an astronomer during his lifetime and this position gave him great honors as well as a good pay check. Kepler went back to teaching in 1612 following the death of Rudolph II. Johannes Kepler died November 15, 1630, but his work was vital to the scientists of later times. His gravitation theory and his laws of planetary motion gave future scientists a more correct knowledge of our solar system by augmenting and refining the Copernican theory.