Create planets and watch the system evolve! T to turn on/off trails. C to clear R to reset the program Arrow keys to change what planet is being created Space to place a planet. PLACING A PLANET: Circular orbit: Just click to send the planet in a circle at the distance from the sun that the mouse currently is. Drag 'n' drop: Click once to set a starting position for the planet, then "pull" the mouse out from the planet to set its velocity. Let go to send the planet flying!