3
Phases
of the Moon and its orbit around the Earth (2).
Suppose you are asked when the first quarter moon will rise, when it will be overhead, and when it will set. Which side will be illuminated?
•If it is
first quarter, it has moved ¼ revolution around from the new moon position, so it is at the top of the diagram.
•For a
person standing on the earth, the moon would rise at noon, be overhead at
6 pm, and would set at midnight.
•It has to
be the side towards the sun which is illuminated.
Imagine yourself
lying on the ground at 6 pm, head north, right arm towards the west.
That west (right) arm points towards the sun. That must
be the side which is
illuminated.
From our text:
Horizons, by Seeds