Kepler's laws of planetary motion explaining how the planets' speeds varied, and using elliptical orbits rather than circular orbits with epicycles. Isaac Newton showed in 1687 that relationships like Kepler's would apply in the Solar System to a good approximation, as a consequence of his own laws of motion and law of universal gravitation. Kepler's laws improved the model of Copernicus. If the eccentricities of the planetary orbits are taken as zero, then Kepler basically agreed with Copernicus: The eccentricities of the orbits of those planets known to Copernicus and Kepler are small, so the foregoing rules give fair approximations of planetary motion, but Kepler's
Clarke's three laws Clarke's three laws British science fiction writer Arthur C. Clarke formulated three adages that are known as Clarke's three laws, of which the third law is the best known and most widely cited. They were part of his ideas in his extensive writings about the future. These so-called laws include: One account claimed that Clarke's "laws" were developed after the editor of his works in French started numbering the author's assertions. All three laws appear in Clarke's essay "Hazards of Prophecy: The Failure of Imagination", first published in "Profiles of the Future" (1962). However, they were not published at the