Curious Kids: What would happen if the world split in half?

The Conversation contributed the article to Space.com's expert voices.

Jonti Horner is a professor at the university.

What would happen if the world splits into two?

The answer is that it would be the end of the world as we know it. It would be a terrible day if life on Earth ended.

It's very rare for an event to tear a planet in half. When our solar system was young, things like that happened a lot.

If gravity was halved, what would happen?

Playing detectives

Calculating the position of the solar system is akin to being a detective. We look at all the objects that are out there. We get clues about what the solar system was like when it was young by studying them.

Scientists call the solar system's evidence of giant collisions. That means what? The last stages of planet formation were violent. There were a lot of planet-size objects floating around, and they smashed into each other.

When two planets smash into each other, it's more than enough to cause a world to be torn apart. We believe that happened to the planet Mercury.

The clues show that Mercury was probably twice as large as it is today. It was only a short time after Mercury formed that another Mercury-size object smashed into it.

A metal core was left behind after a collision stripped away a large amount of Mercury. The scars from a planet torn apart by a collision are still visible four billion years later.

Earth also had a collision

Our own Earth is one of the most famous examples of a planet being torn apart. Astronomers believe that when Earth formed, it was on its own. The moon is a companion to Earth. The moon came from somewhere.

The clues we have gathered tell a really dramatic story. Earth ran into another planet after forming. Theia was about the size of Mars and bumped into us fairly gently.

There is a violent collision between planets. If the collision had happened, the entire Earth would have become molten. It would have destroyed Theia.

The material from Theia and Earth would have ended up in the space around us. The moon was formed because Earth's gravity trapped most of the debris.

When you look up at the moon, you can see that it is a reminder of a giant collision. It was once upon a time that Earth was torn apart by a crash.

What would happen if the earth stopped spinning?

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