His universal law of gravitation explained many things, including the action of tides & the motion of comets
... mechanics showed how universal 
gravitation provided an explanation of falling ... of then unrelated phenomena: the 
eccentric orbits of comets, the tides and their ... How Stuff Works [DOC] [TLE] Tidal force - Wikipedia [PAR] Figure 1: Comet Shoemaker-Levy 9 in 1994 after breaking up under the influence 
of Jupiter's tidal forces during a previous pass in 1992.