Set the chart mode to star atlas. Set the field to 45°. Set the display to center on the Sun and lock on the Sun. Be sure the Sun, Mars, the constellations, and the constellation names are turned on. Set the date to July 1, 2004. Set the step size to 3 days and start the animation. Stop the animation when Mars passes the Sun, and step back and forth until Mars and the Sun are in conjunction. Click on Mars and record the date and the distance of Mars. Repeat for the next three conjunctions of Mars. Using your data, estimate the synodic period of Mars. How can you account for the different distances of Mars at the time of conjunction in terms of the shapes of the orbits of Mars and the Earth?
