This is what the animation window looks like. Remember, the sun is on the right (as indicated by the orientation of the illuminated side of the moon). Before we start the animation it is worth working out the phases of the moon relative to the earth.
At the start of the animation (which is shown here) the moon's position relative to the earth is on the opposite side of the sun. Its illuminated side faces the earth, so it is fully visible; in other words, we have full moon.
After 14 days the moon is between the sun and the earth, so its illuminated side faces away from the earth; we then have new moon. Third and first quarter are reached after 7 days and 22 days, respectively, when one half of the moon's illuminated side is visible from earth.
The animation proceeds in steps of 3 lunar hours, indicated by the movement of the green dots (your home town or closest beach). To emphasise the principal phases of the moon, the animation stops briefly at third quarter, new moon, first quarter and full moon.
| start the animation | skip the animation and continue |
(Note: The size of the animation file is 0.7Mb; if you are doing this exercise over the internet, loading it may take some time.)
© 2000 M. Tomczak