Johannes Kepler formulated the three laws of planetary motion from observations by Tycho Brahe.
Kepler published his first two laws in 1609 and his third in 1619. The laws showed that planets travel in elliptical orbits, sweep out equal areas in equal times, and have orbital periods related mathematically to their average distances from the Sun.
Tycho Brahe’s exceptionally precise observations of Mars gave Kepler the evidence needed to reject the idea that planetary paths were perfect circles. Kepler worked within a Sun-centered framework associated with Copernicus, but his elliptical orbits made the model substantially more accurate.
Isaac Newton later explained Kepler’s laws through universal gravitation. Kepler therefore described the geometry and timing of planetary motion, while Newton supplied a broader physical theory. Kepler’s work helped establish mathematical astronomy and contributed to the later scientific revolution.