It seems you're referring to a misconception about Johannes Kepler's laws of planetary motion. While Kepler formulated his laws based on observations of the six planets known in his time (Mercury, Venus, Earth, Mars, Jupiter, and Saturn), his laws are not limited to those specific planets.

Kepler's laws are universal laws of planetary motion, meaning they apply to all planets, both those known during Kepler's time and those discovered later. His laws describe:

* Kepler's First Law: Planets orbit the sun in elliptical paths, with the sun at one focus of the ellipse.

* Kepler's Second Law: A line connecting a planet to the sun sweeps out equal areas in equal times.

* Kepler's Third Law: The square of a planet's orbital period is proportional to the cube of its average distance from the sun.

These laws have been validated by countless observations and measurements, and they apply equally well to Uranus, Neptune, and even dwarf planets like Pluto, all discovered after Kepler's lifetime.

Therefore, it's incorrect to say that Kepler's laws only hold for the six planets known in his time. They are universal laws of planetary motion and apply to all planets in our solar system and beyond.