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

Still, Kepler’s laws are purely descriptive: they do not help us understand what forces of nature constrain the planets to follow this particular set of rules.

From Textbooks • Oct. 13, 2016

But we can measure the distance to many other solar system objects and use Kepler’s laws to give us the distance to the Sun.

From Textbooks • Oct. 13, 2016

Newton’s universal law of gravitation and Kepler’s laws describe the motions of Earth satellites and interplanetary spacecraft as well as the planets.

From Textbooks • Oct. 13, 2016

With such a force and the laws of motion, Newton was able to show mathematically that the only orbits permitted were exactly those described by Kepler’s laws.

From Textbooks • Oct. 13, 2016

When we send spacecraft to the planets, when we observe double stars, when we examine the motion of distant galaxies, we find that throughout the universe Kepler’s laws are obeyed.

From "Cosmos" by Carl Sagan