Newton improved upon the understanding provided and demonstrated in Kepler's laws in a number of ways. He developed an expression that explained the motion of planets rather than merely predicting it’s empirical relationship. He attributed it to a universal force of attraction between bodies with mass, which is gravity. In doing so he improved the fundamental understanding of the universe with expressions relating to one of its basic forces - involved in far more than just planetary motion.
Kepler's laws, while powerful, were limited in scope. They are only valid in two body systems. They are not able to consider the gravitational effects of other additional orbiting bodies such as other planets when calculating the orbits for any given planet.
Kepler's laws, while powerful, were limited in scope. They are only valid in two body systems. They are not able to consider the gravitational effects of other additional orbiting bodies such as other planets when calculating the orbits for any given planet.