His universal law of gravitation explained many things, including the action of tides & the motion of comets
[DOC] [TLE] Planetary Motion: The History of an Idea That Launched the ... [PAR] Like many philosophers of his era, Kepler had a mystical belief that the circle was 
the ... Isaac Newton demonstrated his universal law of gravitation by showing that 
a comet visible ... Newton's laws of motion and gravity explained Earth's annual 
journey ... His theories also made it possible to explain and predict the tides.