Why do we see different shapes of the moon every night from the earth

Why does the Moon change shape?

An easy way to understand why the Moon changes its shape is to hold a tennis ball in sunlight and view it from different angles. As you move, the sunlit part of the ball will take on the different shapes that are so familiar when you look at the Moon. When the Sun is behind the ball, you will get a thin crescent. Move slightly until the crescent covers half the ball, and you will see the shape of a quarter Moon. With the Sun behind you but not directly behind you will see what is called a gibbous Moon; the reflected light, convex in shape, covers more than half but less than a complete circle.

If the Moon is visible at the same time as the Sun, hold the ball in sunlight and at arm’s length, so that you can no longer see the Moon. Sunshine on the ball will give you an exact replica of the Moon. It is easy to see why. Because it is so far away from the Moon and the ball, the Sun is shining on both at almost the same angle.

As it moves, Spaceship Earth allows us to see the Moon from different positions on different days. Thus, the sunlit part that we see is constantly changing shape. Conventional names describe these different shapes: a new Moon is the crescent at its thinnest and just as it starts to grow once more. During the next twenty-nine and a halfdays, the span between one new Moon and the next, the Moon will appear in all its forms until finally it wanes to its slimmest the old Moon before disappearing.