The phases of the moon as it orbits the earth
Technically, the shape of the moon never changes. What changes is what we saw on Earth. The shape we see depends on the alignment of the Moon, Earth, and Sun.
What changes from days to day is the amount of sunlight we see on the moon. As the moon orbits the earth and the earth orbits the sun, the sun hits the moon at a different angle in relation to the earth.
Exactly the same as the ones we see the Moon go through from Earth, except that Earth does not always turn the same face to the Moon.
The Moon only seems to "change shape". We only see one side of the Moon from Earth. The variation in the amount of sunlight hitting that side of the Moon, as it orbits Earth, is why we see the apparent changes in shape. These changes are called "lunar phases".
The moon never actually changes shape. What we can see at night is the suns reflection from around on the other side of the earth onto the moon, which depending on its position will give us what we can see of the moon at night.
The phase of the moon you see depends on how much of the sunlit side of the moon faces earth.
The variations in how much reflected sunlight we see as the Moon orbits Earth.
The position of the Earth, Moon, and the SunHow much of the sunlit side of the Moon faces the Earth
The variations in how much reflected sunlight we see as the Moon orbits Earth.
We see phases of the Moon because we see the Moon by the Sun's light reflected off it. As the Earth and Moon orbit each other, the Sun-Moon-Earth angle changes, and we see different portions of the Moon's day side. The Sun is a star, so it shines with its own light and so there is no dark side.
The moon can only be seen because it "borrows" the light from the sun. When the moon orbits the Earth the sunlit side of the moon changes - causing the moon to look like it changes shape. Many casual observers often believe that the moon's phases are caused by the Earth blocking the sun's light - this is not true, as the moon only passes through Earth's shadow occasionally.
The Moon is rocky body in orbit round the Earth. Its appearance changes nightly because as it orbits the Earth the amount of its surface we can see illuminated by the Sun changes because of our angle of view.