This interactive is used in Chapter 4.
This Interactive illustrates how the different planetary orbital velocities lead to “looping” or retrograde motion in the night sky. The Interactive will show the view at successive times from the Earth as well as from a “birds-eye” perspective in space. Users will be able to manipulate the size of planetary orbits, plus be able to view the retrograde motion from different perspectives, like what the retrograde motion of Earth looks like from Mars.