When observing the moon one thing we might like to know in advance is when it
is visible – what time it sets, rises, and crosses the meridian (or transits). The applet can
help find these times.
Example 1: What is the meridian crossing (transit) time for a new moon?
Move the moon to its new position. Rotate the earth until the moon is centered on
the meridian (the observer should be located on the earth directly opposite the moon) .
For finding transit times it helps to change the perspective of the horizon diagram (by
clicking and dragging on it) so that we are looking straight down on the diagram. Note
that the transit time of the new moon is 12:00 PM (noon). Complete the rest of the
meridian times in the table below