The laws of planetary motion were discovered by Johannes Kepler, a German mathematician and astronomer, in the early 17th century. Kepler formulated three major laws that described the orbits of planets around the sun. His first law states that planets move in elliptical orbits with the sun at one focus. The second law suggests that a line segment joining a planet and the sun sweeps out equal areas during equal intervals of time. Finally, Kepler's third law establishes a mathematical relationship between the periods of planets and their distances from the sun. His work laid the groundwork for Newton's law of universal gravitation.