Push the Start button to start/restart the simulation from the beginning
(Feb 1, 2013).
Push Pause to pause the simulation. Push Play to resume a paused
simulation.
Push Show Trails to show where each planet has been (only works correctly
if "center on" is set to 0).
Push + to zoom in. Push - to zoom out.
You can choose one of two different integration methods:
Midpoint (Leapfrog) and Hermite.
The accuracy of the simulation is determined by the step size dt.
the warp parameter controls the speed of the simulation (without
compromising quality).