Which astronomer first published the laws of planetary motion?

Johannes Kepler first published the laws of planetary motion.

Kepler, a German mathematician and astronomer, published his first two laws in Astronomia nova in 1609 and his third law in Harmonices Mundi in 1619. The laws describe how planets move around the Sun and replaced the assumption that their paths had to be perfect circles.

His first law states that planetary orbits are ellipses with the Sun at one focus. The second says that a line joining a planet to the Sun sweeps out equal areas in equal times, meaning a planet moves faster when it is closer to the Sun. The third connects a planet's orbital period with the size of its orbit.

Kepler derived these results from exceptionally precise observations made by Tycho Brahe, especially observations of Mars. Isaac Newton later showed that Kepler's laws follow from universal gravitation. Kepler did not discover the heliocentric idea itself; Nicolaus Copernicus had proposed a Sun-centred system earlier, but Kepler gave it mathematically accurate orbital laws.