In my opinion, the greatest impact on our knowledge of orbital motion was provided by Isaac Newton. The evidence to support this is his three laws of motion, which are still used today in calculations to determine the orbits and trajectories of celestial bodies. His laws provide a thorough understanding of the dynamics of two-body systems and provide a solid foundation for further study of orbital motion. While it is true that Newton's laws have been modified and elaborated upon by later scientists, his original contributions continue to be used in astronomical calculations today.