# harmonic law

- See under Kepler's laws.

# Kepler's law

- any one of three laws governing planetary motion: each planet revolves in an ellipse, with the sun at one focus; the line connecting a planet to the sun sweeps out equal areas in equal periods of time (law of areas); or the square of the period of revolution of each planet is proportional to the cube of the semimajor axis of the planet's orbit (harmonic law).

## Origin of Kepler's law^{}

after J. Kepler

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