Astro*Dictionary
by Michael Erlewine

1 article for
"Kepler's Laws"

The laws which describe planetary motion.

In l609, Johannes Kepler gave the world his first two laws of planetary motion. The first established that the orbit of a planet is an ellipse. The second described the mathematics that determine speeding up and slowing down of a planet at different points in its orbit. The third, announced in 1618, established the relationship between the size of the orbit and the time of revolution, or length of a planet's year. These three laws resolved most of the great problems in celestial mechanics, and made a correct understanding of planetary motion possible. Kepler's laws advanced Copernicus's heliocentric theory from a hotly contested topic to a mathematically defensible theory, and paved the way for Newton's laws of gravitation and motion.

 

See also:
♦ Kepler, Johannes ♦ Copernican Theory ♦ Ellipse ♦ Celestial ♦ Newton