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Click the mouse to create an object at a point on the screen.
Drag the mouse before letting go to give it an initial velocity in that direction with a magnitude corresponding to how far you drag the mouse.


E Create earth-mass objects (default)
S Create solar-mass objects
R Reset the screen (Restart orbits of planets)
C Clear the screen (Remove all objects)
L Make trails longer (may slow down computer)
K Make trails shorter
- (not on Num Pad) Slow everything down
+ (not on Num Pad) Speed everything up
Z Zoom in
X Zoom out
Space Bar Pause the simulation (can still make objects)

You won't make a stable binary star system.

Questions, comments, or suggestions? Email me at

Last updated 12/31/08.