On my game (see link below sig) I want to set up things in the world as realistic as possible. It has three moons, one large, though not quite as large as our, and two smaller. What I need to know, is how can I determine the orbital periods and respective size appearance in the sky of the three so that they are pretty much in position to not interfer too much with each other's orbits.
I also need a way to create an equation to describe the planet's position against the stars. Stars I can simply do as a circle about the pole, but how do I get the planets to move correctly with respect to the stars?