Answer:
The positions of the moon, sun, and Earth in relation to each other cause the phases of the moon.
The phases of the moon are caused by the positions of the moon, sun, and Earth in relation to each other. As the moon orbits around the Earth, the amount of sunlight that reflects off its surface changes, which creates the different phases of the moon that we observe from Earth. When the moon is between the Earth and the sun, we see a new moon, and when the Earth is between the moon and the sun, we see a full moon. The phases in between are known as a crescent, first quarter, gibbous, and third quarter. The changing positions of the moon, sun, and Earth relative to each other create unique patterns of phases that we see over time.