Johannes Kepler is known for which discovery in astronomy?

discovering planets around other stars

determining planetary laws of motion

recording 20 years of data about planetary motion

proposing the heliocentric model of the solar system

Johannes Kepler discovered the planetary laws of motion.

Determining planetary laws of motion

Explanation

Kepler worked for Tycho Brahe who was recording planetary motion for 20 years. After Brahe's demise Kepler inherited those records of planetary motion. After analyzing those records he put forth the three laws of planetary motion.

Law of Orbits: Every planet in our solar system move in elliptical orbit with sun at one focus It is also called the law of Ellipses

Law of Areas: The imaginary line drawn between the planet and sun will sweep out equal areas in equal period

Law of periods: The square of the time period of the planet is directly proportional to the cube of the semi major axis of the orbit. It is also called the law of Harmonies