The man who stated that planets move around the sun in an ellipse was Johannes Kepler. He formulated three laws of planetary motion, the first of which states:

Kepler's First Law: The orbit of every planet is an ellipse with the Sun at one of the two foci.

This was a revolutionary idea, as it challenged the prevailing geocentric view of the universe. Prior to Kepler, astronomers believed that planets moved in perfect circles around the Earth. Kepler's work, based on the meticulous observations of Tycho Brahe, helped to usher in a new era of understanding about the solar system.