How Did the Moon Form? - Lesson for Kids

Instructor: Diane Sieverson

Diane has taught all subjects at the elementary level, was the principal of a K-8 private school and has a master's degree in Measurement and Evaluation.

Scientists have different theories about how the Moon formed billions of years ago. Come learn about a common theory many scientists have, how they tested their theory and some other cool Moon facts.

What is the Moon?

It's a warm, clear night, the sky is black and the Moon is bright and full. It's so bright you can even see well enough to play with your friends, even though the sun set a few hours earlier. You probably don't think much about the Moon or how it formed since it's always up in the night sky and you can often see it. But when the Earth was very new, it didn't have a moon. Many scientists think that white, glowing ball in the night sky that we see at night had a very explosive, hot start.

The Moon
The Moon

The earth's Moon is a rocky, dry, dusty natural satellite. (There are other planets that have moons as well.) A satellite is something that orbits, or circles continually, around a planet or star. Satellites can be natural, as in the case of the moon, or person-made. Our Moon orbits the Earth. Since it doesn't make its own light, the moon acts like a mirror, reflecting sunlight, which is why we can see it. And the same side of the Moon always points toward the Earth.

The Moon reflecting sunlight
The Moon reflecting sunlight

The surface of the Moon has big craters. It isn't actually completely round, and only twelve people have ever walked on its surface. So how did the moon form? Well, scientists have a common theory or idea explaining how they think it was created, and it's pretty interesting.

A Big Crash

If you've ever driven bumper cars, you've probably crashed into your friends just for fun. Many scientists believe that when the Earth was fairly new, another smaller planet crashed into it and bounced off, like planetary bumper cars. The smaller planet was completely demolished.

But pieces of it mixed with pieces of Earth that broke off during the crash, squeezing and fusing together to form the Moon. However, it definitely didn't look like the Moon we see today.

When it formed, the Moon was so hot that its surface melted like chocolate left out in the blistering sun. It was completely covered in boiling hot liquid rock called magma. That is the same red-hot, thick liquid that bubbles under volcanoes here on Earth. Eventually, it cooled down and became the rocky, dry Moon we look at each night.

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