I am toying with the idea of creating a general orbital simulator. Possibly lacking the proper terminology, here is a basic description of my goal, make that wild dream. Step 1. Working in 2 dimensions, user enters the mass of 1 to N object, their initial position, their initial velocity, and a time calculation interval. For each time interval, the simulator calculates the forces that each body applies to each other body, the summed vector of that force, applies it to the initial velocity, and determine the position at the end of the time interval. It then shows the position of each body. Repeat. Step 2. Add niceties like lines showing where each body has been for some number of iterations so we can better see the activity. Some future step, make it three dimensional. This seems a rather ambitious project so before I start: Do you know of any simulators of this nature? Do you have any advice for a novice in celestial mechanics? Do you think this would be better to attempt on Microsoft Windows or under Linux, I have both. Thank you.