He formulated three laws of planetary motion, the third of which describes this relationship:
Kepler's Third Law: The square of the orbital period of a planet is proportional to the cube of the semi-major axis of its orbit.
This means that planets farther from the Sun take longer to orbit than those closer to the Sun.
While Kepler discovered this relationship through observation and analysis of data collected by Tycho Brahe, it was later explained by Isaac Newton through his law of universal gravitation.
