Kepler's laws of planetary motion

Scientific  

/ kĕp′lərz /

1. Three laws devised by Johannes Kepler to define the mechanics of planetary motion. The first law states that planets move in an elliptical orbit, with the Sun being one focus of the ellipse. This law identifies that the distance between the Sun and Earth is constantly changing as the Earth goes around its orbit. The second law states that the radius of the vector joining the planet to the Sun sweeps out equal areas in equal times as the planet travels around the ellipse. As such, the planet moves quickest when the vector radius is shortest (closest to the Sun), and moves more slowly when the radius vector is long (furthest from the Sun). The third law states that the ratio of the squares of the orbital period for two planets is equal to the ratio of the cubes of their mean orbit radius. This indicates that the length of time for a planet to orbit the Sun increases rapidly with the increase of the radius of the planet's orbit.

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Example Sentences

HR 5183 b spends most of its time loitering in the outer part of its star’s planetary system, then it accelerates and slingshots around its star, consistent with Kepler's laws of planetary motion.

From Salon

All three of Kepler’s laws of planetary motion can be derived from Newtonian principles.

From Literature

While Kepler’s laws of planetary motion and Issac Newton’s law of universal gravitation allowed for the calculation of the relative distances of the planets from the Sun, but nothing was known in absolute terms.

From Scientific American