Distinguish between a waxing moon and
a waning moon.

Waning is the opposite, or decreasing after a full moon, and is always illuminated on the left. Then, there is a waxing or waning Gibbous moon, which means more than half of the moon is illuminated. Waxing means to increase/get bigger, and waning means to decrease/get smaller.

did u get the answer? /? ? / me

i'd say that the moon rock is about 2.2 billion years old.