Of course, the Moon does not really change shape — it just seems as though it does. The Moon orbits the Earth once every 27.3 days. It has no light of its own, but as it moves around, it is lit by the Sun. Only the part of the Moon that is both turned towards the Earth and lit by the Sun is visible on Earth. The amount of the Moon’s surface that can be seen changes as the Moon’s position changes.
You see, the Moon doesn’t actually produce any light at all. The Sun is a ball of burning gas that provides a constant source of light, zooming away from it in all directions. Some of that light bounces off objects in space – moons, planets, asteroids, etc., meaning that the same light bounces into our eyes so we can see them. When you look at the Moon you see the Sun’s light that has reflected off it, to you! I mean, that works for everything: the screen you’re looking at now produces light but turn the device around (tablet, phone, laptop, etc.) – can you see the back of it? Of course you can, but it isn’t producing light like the screen. So, if you can see it, where’s the light coming from? That light, reflecting off the back of the device to your eyes, allows you to see it.
Why the Moon changes shape, there’s the Moon, it looks like it’s hanging up there in the sky, but in fact, it’s travelling around the Earth, but the Earth is spinning too. OK then, on a clear night the amount of Moon that you can see is dependent upon two things: where it is on its LUNAR CYCLE (takes about a month … or “moon-th”!) and where the Sun is in relation to the Moon. You see, if the face of the Moon you can see is also facing the Sun (even though it’s night time to us), then it’s fully lit by the Sun’s light. That’s a full Moon.
To us, the Sun may have set, but remember, its light is still streaming out in all directions and any that falls on the Moon may be reflected in your eyes. Now, as the Moon undertakes its lunar cycle, different faces of the Moon are lit by the Sun and, depending on where you are, you may be able to see all of the lit side (Full Moon) or only part of the lit side (Crescent moon/Gibbous Moon, etc.). Golly, complicated! Well, some pictures really help to understand this. So, let’s have a look at the different shapes (or phases) of the Moon.
Picture Credit : Google
