The Moon doesn't actually change shape during its phases. The phases of the Moon are an illusion caused by the changing angles of sunlight reflecting off its surface as it orbits the Earth.

Here's how it works:

* The Moon is a sphere: It has a roughly round shape, like a ball.

* Sunlight illuminates half the Moon: Just like Earth, half of the Moon is lit by the Sun at any given time.

* Our perspective changes: As the Moon orbits Earth, we see different amounts of the illuminated half, creating the illusion of changing shape.

Think of it like a coin:

* Full Moon: You see the entire illuminated face, like seeing the whole coin.

* New Moon: You see the unilluminated face, like seeing the edge of the coin.

* Crescent, Quarter, Gibbous: You see varying amounts of the illuminated face, like seeing part of the coin.

So, the Moon stays the same shape, but our view of it changes, creating the familiar phases.