Johannes Kepler did not discover any planets. He is famous for his laws of planetary motion, which describe how planets move around the Sun.

Here's what Kepler did:

* He used the meticulous observations of Tycho Brahe, his mentor, to develop his laws.

* These laws explained the elliptical orbits of planets, the varying speeds of planets in their orbits, and the relationship between a planet's orbital period and its distance from the Sun.

While Kepler didn't discover new planets, his work laid the foundation for our understanding of the solar system and revolutionized astronomy.