Mercury and the Sun
1) Use checkboxes (Seconds, Minutes, etc) to choose time interval. "Hours" and "Days" work best for animation.
Use slidebar at right to control simulation speed. There are 7 speeds, 3 forward (right), 3 reverse (left) and one neutral
(center), although depending on your computer speed, there may be no difference between the two faster speeds. The
bar is initially set at the slowest forward speed. Use "Reset Time" to return to present.
2) Use the black and white "craters" to mark Mercury's tidal bulges. Note how
one or the other crater is always pointed straight at the Sun during Mercury's
3) Compare the "Mercury" in the upper left to the orbiting Mercury to verify that it rotates at a constant velocity.
4) Use the Julian Day to determine the period of Mercury's orbit and its spin rate. What is the ratio of these two periods?