Usage:

Move the mouse cursor onto the canvas can pause the motion, move out to continue;
Drag the slider bar to change the motion speed;
Click the Helicentric button to change between helicentric or geocentric system;
Click draw path to draw the orbit based on selected system.

Suggestion:

Using the lowest speed to draw orbit path on geocentric system.

Test passed on the latest Chrome and Opera (2014-06-27)

Source Code under MIT license

Sun mercury venus earth mars jupiter saturn uranus neptune