Set chart mode to star atlas, the status line to on, and the field to 45°. Be sure both Mercury and the Sun are displayed. Set the animation display to lock on the Sun and set the step to 1 day. Then step ahead day by day to watch Mercury's motion with respect to the Sun. You should see the stars slipping steadily by toward the right (west). Stop when Mercury is at greatest eastern elongation (left of the Sun) or greatest western elongation (right of the Sun). Left click on Mercury and then right click and stretch the line to the sun. Record the elongation, whether it is an eastern elongation or western elongation, and the date. Repeat for the next four greatest elongations. How consistent are your values for the greatest elongations? If they're not all the same, give some reasons why they aren't. What is the length of time between greatest eastern elongations? Between greatest western elongations? How do these periods of time compare with the synodic period of Mercury?
