The Moon's phases are not caused by anything covering it, but by the changing angles of sunlight hitting the Moon's surface as it orbits the Earth.

Here's the breakdown:

* The Moon doesn't produce its own light. It reflects sunlight.

* As the Moon orbits Earth, the angle at which sunlight hits its surface changes.

* We only see the illuminated portion of the Moon.

Think of it like a ball in the sunlight. If you hold it straight up, the entire top half is lit. If you tilt it, only a part of the top is lit. The Moon's phases are like that tilting, showing different amounts of the illuminated surface.

So, the Moon's phases are a result of geometry and the interplay of light, Earth, and the Moon's position.