What this applets does
This applet shows the Sun, the inner three planets, and the earth’s moon, and how they move in relation to each other.
You can choose any of these five bodies to appear as a fixed centre to see how the others move in relation to the chosen body.
Use the tick boxes to trace out the path of any bodies.
NotesThis is a highly simplified model for several reasons, including, but not limited to the following:
- The applet assumes that planets’ orbits around the sun and the moon’s orbit around the earth are circular. In reality, this is not the case.
- The orbit times have been rounded very slightly but are broadly reflective of reality. e.g. Mercury completes just over four orbits of the sun in the time it takes earth to complete one.