Two planets & a sun - a digital triptych
The motions of a Sun and two planets as seen in each of their coordinate systems.
You can animate the motion by clicking on the lower left hand corner of the screen.
You can show the trajectories by checking the trajectories checkbox.
You can show the triangle formed by the the bodies by checking the triangles checkbox.
Can you see a relationship between the apparent motion of Mars from Earth and the
apparent motion of Earth from Mars? Can you explain the relationship you observe?
Why does the triangle formed by the three bodies look the same in all three coordinate systems?
An astronomical unit (AU) is approximately the distance between the Earth and the Sum. The initial setting has Mars at 1.5 AU from the sun, which is approximately correct. You can vary this setting and see how this effects the retrograde motion. (The speed of the planet depends on the distance from the sun. The worksheet computes the speed consistent with the laws of planetary motion.) What do you predict will happen as this distance increases?
you
This worksheet is a modified version of a worksheet of the same name created by Judah Schwartz: https://tube.geogebra.org/user/profile/id/25758