How to simulate planets orbit curve around the sun ? Hi I'm about to write a java program where I wish to simulate planets orbit curve around the sun, so that I can set the speed of a planet and mass of planet and sun and simulate the curves around the sun (just basic simulations). I only know high-school level physics but I know university level mathematics. I want to build my programs on newtons laws. I know that there are plenty of others programs that can do such simulations, but I wish to know the theory and math behind it so that I can build my program from ground up. I know newton laws of gravity, but I do not understand how to apply them to a simulation, and when I fool around with the formulas I manage to get different results depending on how I interpreted applying the formulas to a simulation. I hope that someone here will be so kind to explain me the theory of doing such a simulation or tell me where I can find books, documents, or websites about it. I have tried searching on the net, but have just got more confused. Thanks.