8 March 1618 March 7, 2014 Author: Staff Johannes Kepler finds the third law of planetary motion. Famous Words of Inspiration..."Any fool can make a rule." Henry Thoreau — Click here for more from Henry Thoreau Related posts: 8 March 1983 8 March 1978 23 March 1983 3 March 1913 Categories: History Tags: 1618, 8 March