Kepler's Laws of Planetary Motion

Written by Jerry Ratzlaff on . Posted in Classical Mechanics

Kepler's laws describe the motion of the planets in the solar system.

Kepler's first law (Law of orbits)

The orbit of every planet is an ellipse with the sun at one of the two foci.

Kepler's Second law (Law of areas)

A line joining a planet and the Sun sweeps out equal areas during equal intervals of time.

Kepler's third law (Law of Periods)

The square of the orbital period of a planet is directly proportional to the cube of the semi-major axis of its orbit.

Kepler's third law formula

 $$\large{ P^2 = a^2 }$$

Where:

$$\large{ P }$$ = planet's distance from the sum

$$\large{ a }$$ = semi-major axis of the planet's orbit