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| 1. Turn off the daylight display and the horizon display.
Open the "Planet" Palette, center on the Sun, and then
lock on the Sun. Use the "Settings" button to set Orientation
to Equatorial. Use the Selection Tool to find
Mercury. Set the time step to 1 day. 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). Use the Angular Separation
Tool to find the angle between Mercury and 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?
2. Turn off the daylight display and the horizon display. Open the Viewing Location window and either return to your home location or set the location to a city near you. Open the "Planet" Palette, center on the Sun, and then lock on the Sun. Use the "Settings" button to set Orientation to Equatorial. Use the "Zoom" button to magnify the Sun until it is about 4 inches across on your computer monitor. Set the time to 1 P.M. on June 4, 2012. Set the time step to 15 minutes. Step forward in time until you see Venus start to cross the disk of the Sun. (During the actual transit of Venus, the disk of Venus will appear much smaller relative to the Sun than it appears in "Starry Night.") Record the time. Step forward again until Venus leaves the disk of the Sun. Record the time. How long did the transit of Venus last? Given the beginning and ending times, how much of the transit will you be able to see from your home? |