The Moon does not appear in the same shape every day, it is ever changing. On some days, it looks like a shining disk, on some days it looks like an elongated C. These different shapes of the Moon are called the phases of the Moon.
The orbiting of the Moon around the Earth is the secret behind the different phases of the Moon. We already know that the Moon has no light of its own. As the Moon moves around the Earth, different parts of it are lit by the Sun, thus causing different phases. In a fortnight’s time, the Moon goes from full moon to new moon.
Picture Credit : Google