Moon Phase Flip Books
Background Information: As the moon circles the Earth, the
shape of the moon appears to change; this is because different
amounts of the illuminated part of the moon are facing us. The
shape varies from a full moon (when the Earth is between the sun
and the moon) to a new moon (when the moon is between the sun
and the Earth).
The revolution of the Moon around the Earth causes the Moon to
appear to change shape in the sky. These apparently different
shapes are called "phases" of the Moon.
The Moon passes through a cycle of eight phases which repeats
itself every 29.5 days. There is no definite starting point for
the cycle, but phases follow one behind the other in a strict
The diagram above shows what the different phases of the Moon
would look like as seen from Earth.
The Moon repeats certain phases: there are two crescent,
gibbous, and half phases each month (each cycle).
New Moon: lighted side of the Moon faces away from the Earth.
Waxing Crescent: a small part of the Moon appears lighted and
grows larger on successive days.
First Quarter: the right half of the Moon appears lighted, with
the lighted part growing larger on successive days.
Waxing Gibbous: more than half of the Moon appears lighted, with
more and more becoming lighted on successive days.
Full Moon: lighted side of the Moon faces toward Earth.
Waning Gibbous: more than half of the Moon appears lighted, with
less and less becoming lighted on successive days.
Third Quarter: the left half of the Moon appears lighted, with
the lighted part growing smaller on successive days.
Waning Crescent: a small part of the lighted Moon is visible and
grows smaller on successive days.
These phases are not exactly identical, however. Look closely at
the diagram. You will notice that during phases 1 through 5, the
amount of lighted area INCREASES over time from right to left.
When this occurs, the Moon is said to be WAXING.
During phases 5 through 8, the amount of light area