I made a model solar system to help me learn opengl in jitter and to apply some of the ideas I got from Rob Hamilton's and Chris Platz's "Designing Musical Games" summer workshop. (Emulating their piece Echo::Canyon).
The rotation/orbit speeds for the planets are more or less correct as are the relative sizes of the planets. The sun is only 1/10th the size it should be. The distances between the planets are something like 1/1000th of the actual scaled distances. (Either the outer planets were so far out that it was impossible to find them in the game or the inner ones were so close to the sun that they end up inside of it. Reducing the size of the sun was my compromise. It's easy to underestimate how incredibly far apart the planets are relative their size: If the moon were one pixel)
The sounds are generated using FM synthesis with feedback (done in gen). As you near a planet, a synth will fade in. The parameters for each of these synths are taken from the rotation and orbit rates of each planet... just transposed up many many octaves. Colliding with the monolith cues a short (and much much worse) parody of the stargate sequence from 2001 a Space Odyssey.
The whole thing is done live and controlled using OSC messages sent from my iPad. This version was done on my laptop... It is just slightly too computationally intensive for it to run smoothly.