Hi, i'm attempting to simulate the Solar System in Java. I'm particularly interested in simulating orbits of celestial bodies that might enter our solar system. Therefore I need real data for my simulation. That is: x,y,z coordinates of planets with respect to the Sun (taking the sun to be at the origin) as well as their velocity components in all directions at some point in time. I'm sure this sort of information is to be found online, however I have not yet been successful in doing this. I have found http://cohoweb.gsfc.nasa.gov/helios/planet.html" [Broken] at NASA talking about planets coordinates, but I couldn't get this to give me any useful information. Also, which numerical method would you choose to do this. Do you think a Runge-Kutta 4th order would be accurate enough for this?