When you look into the sky at night, often you are able to see the moon. The moon may not look the same every night that you see it. Some times it may look like a circle and other times it may look like a circle cut in half. What you are seeing is the different phases of the moon.

What causes the moon to change shape?

Just like the Earth moves around the sun, the moon moves around the Earth. It takes 24 days for the moon to move all the way around the Earth. There are four basic stages during this trip that the moon makes.

To see how the Earth moves around the moon and the different phases of the moon, click on the moon at the end of this paragraph. Make sure that the box next to "Point of View" says "Both" in it. If it doesn't, click on the arrow next to the box and highlight the word "Both".

In one phase of the trip around the Earth, the moon is in between the sun and the Earth. The moon is called a new moon. The side of the moon that is facing the sun is lit up by the light given off by the sun. The side that we see on Earth is dark. This is when we do not see a moon at night.

In another phase in this trip is when the Earth is in between the sun and the moon. The moon is called a full moon.

When the moon is either above or below the Earth, we are able to see half of the part of the Earth which is lit up, and half that is dark. When we are able to see only half of the moon, the moon is in its first and third stage. The first time that you are able to see half of the moon, it is in the first quarter of its trip around the Earth. So, the moon is called a quarter moon.

When the moon is in between the new moon phase and the quarter moon phase, you only see a sliver of the moon. This is called a crescent moon.

To download a slide show on the four phases of the moon that we just went over, click here. Make sure to ask your teacher before you download anything.

When the moon is in between the quarter moon phase and the full moon phase, you see more than half of the moon, but not all of it. This is called a gibbous moon.

The cycle of the moon is broken down into two sections. When the moon travels from being a new moon to a full moon, it is said to be a waxing moon. This is when the moon looks like it is growing.

When the moon travels from being a full moon towards being a new moon again, it is said to be a waning moon. This is when it looks like the moon is getting smaller.

To see a picture of the different phases of the moon, click here.

To see what the moon looks like on any day of the year, any year you choose, click here.

If you would like to do any easy experiment to see the different phases of the moon, click here.

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