The Terran System
This is a simulation of the Terran System,
which consists of our Earth and its moon.
The Moon's orbit is shown as if it moved exactly in the plane of the screen,
so the true orbit geometry (semimajor axis and eccentricity) is as shown.
The Earth is shown as it appears from directly above the ecliptic plane.
Usage:
'Start/Stop' begins and halts the simulation.
The elapsed time in days is shown on the screen.
'Orbit' toggles display of the moon's orbit.
'Labels' shows the name of the planet and satellite.
'Scale+' and 'Scale-' change the scale by a factor of two.
'Faster' and 'Slower' change the speed of the simulation by a factor of two,
computer speed permitting.