Turn off the daylight and horizon displays. Use the
"Planet" Palette to center on Mars and lock on Mars. Click
under the "C" column of the "Planet" Palette to track the
celestial path of Mars among the stars. Set the date to
April 1, 2005, and the time step to 2 days. Use the "Settings"
button to select "Path Settings." Turn the date off,
and leave the Circular Marker and Connecting Line on.
Click Apply and OK. Start the clock and watch Mars
move among the stars. When Mars undergoes retrograde
motion, wait until it is as far west among the stars as it gets
during that retrograde loop and then stop the clock. Click
on the constellation button on the "Display" Palette in the
vertical toolbar to identify the constellation in which the
retrograde motion occurred. Record the month of the retrograde
and the constellation in which it occurs, and
sketch the shape of the retrograde loop. Repeat for the next
three retrograde loops. Use your data to estimate the synodic
period of Mars. When do you think the retrograde
motion of Mars will appear in the constellation of Taurus
again? Do you see a pattern to the changes from one retrograde
loop to the next?
