Liberal Dictionary English Dictionary
- 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.
A German astronomer of the late sixteenth and early seventeenth centuries. Kepler’s three laws governing the motion of the planets made modern astronomy possible. His first law includes his discovery that the orbits of the planets are ellipses.