Asteroids aren’t spread out over the Solar System, but are grouped together in asteroid belts. There are three such asteroid belts in our Solar System.

The first one is between Mars and Jupiter. It’s simply called the Asteroid Belt. There are over a billion asteroids in this belt and the average distance between each one is 500,000 km. That shows you how big space really is.

The second belt is called the Kuiper Belt, after Dutch astronomer Gerard Kuiper. It’s twenty times as wide as the Asteroid Belt and circles around the planets of our Solar System. It has the dwarf planet Pluto in it.

There is another group of asteroids in our Solar System, a thousand times further than the Kuiper Belt.

It’s called the Oort Cloud, after Dutch astronomer Jan Oort. It’s called a cloud because our Solar System is surrounded by it. It consists of a disc-shaped inner Oort Cloud and a spherical outer Oort Cloud. It defines the edge of our Solar System because the Sun’s gravity can only just reach it. That’s how far it is.

Oort Cloud
The Kuiper Belt and the Oort Cloud

Just because the asteroids are organized in belts doesn’t mean that there are no other asteroids flying around. Sometimes an asteroid randomly flies out of its belt. Scientists don’t yet fully understand why this happens.

At the moment, there are over 800 asteroids that will come dangerously close to Earth. Around 150 of those could cause serious harm to our planet if they were to hit us.

Asteroids that enter our atmosphere are known as meteors or meteorites. Meteors burn up and never hit the ground. Meteorites hit the ground. As you might have guessed, they’re the more dangerous ones.

A meteorite caused the dinosaurs to go extinct 65 million years ago. It entered our atmosphere so fast that it squeezed the air in front of it and caused huge fires along its path. The meteorite crashed in Mexico and blew out earth and rock for thousands of kilometers.

Everything hundreds of kilometers around died instantly. The shock caused many earthquakes and tsunamis. Volcanoes erupted and the Earth was covered in a layer of soot for years, blocking out nearly all sunlight. 75% of all animals eventually died as a result.

Even with today’s technology, it’s impossible to know if such an asteroid is approaching Earth again. We’ll probably only know seconds before it hit. So for our sanity, let’s hope the asteroids stay nicely grouped together in their belts.