Why Does the Moon Change its Shape?

Whenever you look at the sky at night, you see the moon changing its shape. One day of the month, it looks like a perfect circle, illuminating the clear night sky, and on another day, it completely vanishes! Does the moon change its shape every night? Well, no. If you’re curious about if and why the moon changes its shape, read on untill the end.

Why Does the Moon Change its Shape?

We do say that the moon is changing shape, but scientifically, it doesn’t. As the Moon revolves around the Earth, and while shifting its positions, we get to see the lit side. The Moon takes 27.3 days to orbit Earth, but it takes 29.5 days to pass its eight different phases and complete a lunar month.

When the Earth comes between the Sun and the Moon, the side of the Moon that faces the Earth gets fully lit, and we get to see it. If the Moon is between the Sun and the Earth, then the side of the Moon that faces the Earth is dark. That is when we cannot locate the Moon in the sky. The rest of the phases of the Moon are essentially in-betweens of these two phases.

There are basically the conditions for the Moon when it appears bigger or smaller. When you see it getting smaller, that is, a tiny portion of the lunar surface is illuminated, it is called waning. When the Moon looks bigger, it is called waxing.

The Moon doesn’t have its own light, unlike the Sun, so technically, there is nothing like moonlight. The so-called moonlight is the sunlight reflecting the lunar surface. The Moon borrows a little bit of light from the Sun to look pretty in the dark sky.

We never get to see the complete Moon, yes that’s the truth! If you ever thought that during a full Moon night, you are watching the complete Moon, you are wrong. The same goes for when you look at the half Moon. We only get to see the side of the Moon that is lit up, and only one side is lit up at a time.

Phases of the Moon

Let’s talk about the different phases of the Moon. As mentioned above, the Moon goes through eight phases before completing a lunar month. The eight Moon phases are as follows:

1. New Moon

During this phase, the Moon is completely out of sight. Yes, it is still there, but it is not lightened up. The Sun and the Moon are on the same side of the Earth during this time, and therefore, the Sun’s light overshadows the Moon.

2. Waxing Crescent Moon

Moving forward to continue its phase, the right western edge of the Moon is lit up by the Sun, creating a thin silver crescent. That is when you start to see the crescent shape as it is in its waxing crescent phase.

3. First Quarter Moon

When the Moon is in its first quarter phase, it seems like half Moon, but it is a quarter Moon.

4. Waxing Gibbous Moon

During the waxing gibbous phase, you will see that the Moon appears to be almost fully lit. The side lightened up seems like a gibbous which is waxing daily.

5. Full Moon

Everyone knows the Full Moon period when the Moon shines the brightest in the night sky. At this phase, the Earth is in between the Moon and the Sun, and the side of the Moon facing the Earth is illuminated by the Sun.

6. Waning Gibbous Moon

When the Moon is in its waning gibbous phase, the western edge that was lighted up previously is engulfed by darkness. The gibbous is now waning daily.

7. Last Quarter Moon

In this phase, the Sun lights the eastern half of the Moon.

8. Waning Crescent Moon

Just like the right western edge of the Moon gets lighted up by the Sun and creates a thin silver crescent in Waxing Cresent, here the left eastern edge is lighted up and forms a thin silver crescent. The Moon further keeps waning till the lunar cycle finishes. After that, the Moon again goes back to its first phase, that is, the New Moon phase.

Frequently Asked Questions (FAQs)

1. Why does the Moon change its shape?

The Moon orbits our planet, and as it changes its position, different parts of the Moon are lit by the sun. This creates an illusion and we think that the Moon changes shapes, from gibbous Moon to half Moon to other different shapes.

2. What is the changing shape of the Moon called?

The changing shape is called the Moon’s phases. When the Moon moves and completes a cycle of phases, it is called a lunar month.

3. Why do full moon and new moon occur?

Full Moon and New Moon occur due to the Moon’s phases. When it is a new Moon phase, we cannot see the Moon at all. Yes, it is still there, but in shadow, as sunlight doesn’t hit the moon’s surface at all. The Sun and the Moon are on the same side of the Earth during this time, and therefore, the Sun’s light overshadows the Moon. In the full moon phase, the Earth is in between the Moon and the Sun, and the side of the Moon facing the Earth is illuminated by the Sun.

In Short

The Moon completes its orbit around the Earth, and each lunar day, the Moon shifts its position. The only part that gets lit up by the light of the Sun is seen from our planet. The changing positions of the Moon are called the Moon phases. When the Moon reaches a position between the Sun and the Earth, it becomes a New Moon. When the Earth is between the Sun and the Moon, the side of the Moon facing the Earth receives sunlight and thus becomes a Full Moon.

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