2. Astronomers made two observations of the Moon that were several days apart. Their observations
are shown in the diagram above. The light part of the Moon appeared to get larger over time. Why did
this happen?
a
Between the first observation and the second observation, the Moon rotated so that more
of the light-colored rock on the Moon's surface faced Earth.
b
Between the first observation and the second observation, the Moon moved so that the
astronomers were able to see more of the half that faces the sun.