  To view the seventy years of research after Newton died as merely tying up the loose-ends of the Principia or as simply compiling more evidence for his theory of gravity is to miss the whole point. Research predicated on Newton's theory had answered a huge number of questions about the world dating from long before it. The motion of the Moon and the trajectories of comets were two early examples, both of which answered such questions as how one comet differs from another and what details make the Moon's motion so much more complicated than that of the satellites of Jupiter and Saturn. In the 1770s Laplace had developed a proper theory of the tides, reaching far beyond the suggestions Newton had made in the Principia by including the effects of the Earth's rotation and the non-radial components of the gravitational forces of the Sun and Moon, components that dominate the radial component that Newton had singled out. In 1786 Laplace identified a large 900 year fluctuation in the motions of Jupiter and Saturn arising from quite subtle features of their respective orbits. With this discovery, calculation of the motion of the planets from the theory of gravity became the basis for predicting planet positions, with observation serving primarily to identify further forces not yet taken into consideration in the calculation. These advances in our understanding of planetary motion led Laplace to produce the four principal volumes of his Traité de mécanique céleste from 1799 to 1805, a work collecting in one place all the theoretical and empirical results of the research predicated on Newton's Principia. From that time forward, Newtonian science sprang from Laplace's work, not Newton's.