01 / 04
Why phases happen
Half of the Moon is illuminated by the Sun. From Earth, we see different portions of that illuminated half as the Moon orbits us.
02 / 04
Try the terminator
The boundary between lunar day and night casts long shadows. Binoculars can reveal craters particularly well near that line.
03 / 04
Observe again tomorrow
Sketch the visible phase at roughly the same local time on consecutive nights. Notice how the illuminated area changes.
04 / 04
Compare the shadows
Near the terminator, changing sunlight makes crater rims and mountains stand out. Observe the same feature over several evenings.