[ kĕp′lər ]
German astronomer and mathematician who is considered the founder of celestial mechanics. He was first to accurately describe the elliptical orbits of Earth and the planets around the Sun and demonstrated that planets move fastest when they are closest to the Sun. He also established that a planet's distance from the Sun can be calculated if its period of revolution is known.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.