Kepler's laws

English

Etymology

For Johannes Kepler, German mathematician and astronomer.

Noun

Kepler's laws pl (normally plural, singular Kepler's law)

1. (astronomy) The three laws of planetary motion discovered by Kepler in the early 17th century, stating that (i) the orbit of a planet is an ellipse with the Sun at one of the two foci, (ii) a line segment joining a planet and the Sun sweeps out equal areas during equal intervals of time, and (iii) the square of the orbital period of a planet is proportional to the cube of the semi-major axis of its orbit.

Related terms

• Kepler's equation