By Chris Gothman and Hannah Braem
Cause: Johannes Kepler left to Prague to become an assistant to another astronomer, Brahe. After being assigned to study the orbit of Mars, Brahe's assistant was well on his way to developing the laws of planetary orbit.
Significance: Johannes Kepler proposed three laws of planetary motion. They described the motion of planets in a sun-centered solar system, and are considered as an accurate description of the motion of any planet and any satellite.
Characteristics: He was born on December 27, 1571, in Weil der Stadt, Württemberg, in the Holy Roman Empire of German Nationality. He had a wife and two kids.
Fun fact: Brahe only let Kepler see part of his data because he did not trust Kepler very much as his assistant since he was afraid his bright peer may surpass him. Ironically after assigning Kepler to study the orbit of Mars in hope that it would occupy him while he formulated his own theory of the solar system, it ultimately helped Kepler discover the planetary laws due to Mars' special elliptical orbit.