Functions: The choice menu at bottom right gives a list of Earth, Jupiter, and the purported extrasolar planets. 'Start' begins the simulation. 'Stop' halts the motion, which is resumed by a second 'Start'. 'Reset' returns the simulation to time=0. 'Orbits' highlights the elliptical orbit followed by the reported planet. 'Grid' shows a calibrated length scale (in [AU]), centered on the stars' center of mass, 'Data' shows the elapsed time (in [yrs]), the star-planet separation (in [AU]) and the x and y components of the star's velocity, which would be observed as a Doppler effect. 'Labels' attaches text labels to the star and planet. 'Params' shows the system parameters: planet mass (in [M_Jupiter]), star mass (in [M_sun]), the semimajor axis (in [AU]) and eccentricity of the planet's orbit, and the orbital period (in [yrs]).

Designing Your Own: 'Sliders' activates the scrollbars at the bottom, so you can design your own star and planet system and see how the properties (such as the geometry and period) change. (The choice window then blacks out, to indicate that you are not simulating a system from its list.)