Ill start by appologizing for not using LaTex, but i havent figured out how it works yet and im a little bit impatient. The equation is probably a simple one. Im not very trained in math but happen to have some interest in physics, especially astronomy, and this is used in astronomy but i think this is a better place to ask this question, hope i havent posted this thread all in the wrong place. To the question. How do I get from 2GMr/D^3=Gm/r^2 to D=(2M/m)^1/3r A step by step explaination would be appreciated. And again, excuse me if im not following the general rules for posting but Ill better myself in the future. Thanks!!