Question

What causes the phases of the moon?

Answer 1

As the moon orbits the earth, one side of it is in the sun's light, and the other in shadow. Now, at any one time, we can only see half the moon's surface, is the side facing us. So as the moon orbits the earth, the side facing earth is illuminated by varying amounts in the sun light. So when we look at the moon, we see part of it in sunlight, and part of it in shadow. And so, we have the phases of the moon.

The phases of the moon change as the moon orbits the Earth. The changing, relative positions of the sun, moon and earth give us the different phases of the moon.

Answer 2

How and where the sun moves around the earth.