* Kepler did NOT discover that planets orbit the Sun. The concept of heliocentrism (the Sun being the center of the solar system) was proposed by Nicolaus Copernicus in the 16th century.

* Kepler built upon Copernicus' work. He used extensive observations by Tycho Brahe to develop his three laws of planetary motion, which accurately described how planets move in elliptical orbits around the Sun. These laws were a major step forward in understanding our solar system.

So, while Kepler didn't discover heliocentrism, his laws of planetary motion solidified the idea and revolutionized our understanding of how planets move.