Kepler's laws

British  

plural noun

1. three laws of planetary motion published by Johannes Kepler between 1609 and 1619. The first states that the orbit of a planet describes an ellipse with the sun at one focus. The second states that, during one orbit, the straight line joining the sun and a planet sweeps out equal areas in equal times. The third states that the squares of the periods of any two planets are proportional to the cubes of their orbital major axes

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Example Sentences

Although only 1.5 kilometers in diameter, smaller than many college campuses, Dactyl provides scientists with something otherwise beyond their reach—a measurement of the mass and density of Ida using Kepler’s laws.

From Textbooks • Oct. 13, 2016

According to Kepler’s laws of planetary motion, the shape of the orbit is elliptical, with the Sun at one focus of the ellipse.

From Textbooks • Mar. 30, 2016

Note again that while, for historical reasons, Kepler's laws are stated for planets orbiting the Sun, they are actually valid for all bodies satisfying the two previously stated conditions.

From Textbooks • Aug. 12, 2015

Kepler’s laws showed that Copernicus’s basic ideas were true.

From Textbooks • Jan. 1, 2012

Ptolemy gave the astrologers the information they needed, and Newton explained Kepler’s laws of planetary motion.

From "The Invention of Science" by David Wootton