The difference between the full moon and the new moon.
The full moon is fixed in its orbit at the full phase.
This occurs when the moon is on the opposite side of the Path from the Sun, lighting up the full face of the moon from our perspective on Earth.
New Moon is fixed in its orbit at the new phase.
New moon occurs when the moon is between Earth and the Sun ,and thus the side of the Moon that is in shadow faces Earth.
