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Skip to 0 minutes and 6 secondsSpace rocks. Our solar system is a fast and fascinating place. Between Mars and Jupiter we find the asteroid belt. Due to the mighty gravitational effects of Jupiter, these chunks of rock and metal couldn't come together to form a planet and, instead, made up a solar junkyard of sorts. [CHEERING] This is a crowded place to be an asteroid. Sometimes they collide with each other and get knocked off course, and even out of the belt all together on a very different journey through the solar system. There are lots of names associated with space rocks. So what's the difference? Well, the bigger rocks are called asteroids, the smaller are meteoroids. Are when they fly through the Earth's atmosphere, they're called meteors.

Skip to 0 minutes and 48 secondsIf they manage to survive their burning descent through our [BOOM] atmosphere and lands on Earth, we call them meteorites. Some meteorite contain iron which makes them very dense, dark, and magnetic. They're the oldest thing you could ever touch, as they are the same age as the solar system. The gas giant Jupiter marks a boundary in the solar system called snow line, beyond which, objects contain a lot of ice. Past the other three gas giants, we find a huge ring of ice chunks large and small called Kuiper belt where the dwarf planet Pluto lives. Even more of these ancient dirty snowballs exist in a huge bubble called the Oort cloud.

Skip to 1 minute and 25 secondsThese icy objects can get bumped off course sometimes to become comets that journey past the planets towards the sun. Some collide with other objects and get smashed to bits. Others head towards the sun and form long beautiful tails as their icy surfaces warm up. Here, they will either fall into the sun, never to be seen again, or they will survive and speed back home beyond the snow line. Here on Earth, we're treated to a spectacular natural firework displays in the sky from orbiting comets. As they get close to the sun, they burp, splatter, and crumble, leaving behind a trail of debris.

Skip to 1 minute and 58 secondsAt certain times of the year, the Earth ploughs through these trails, and bits of comet flare up as they fly through our sky and become meteors. The early Earth was hit by thousands of comets and asteroids. It is thought they brought water to our world. Comets may have also brought the ingredients of life to the Earth. On the European Rosetta mission could help us unlock secrets about the origins of life on our planet.

We explain it

Take a look at this Space Rocks video which shows our approach to explaining asteroids, meteors, meteorites and the differences between them.

Using the information in this video think about how you would now answer the question What is an asteroid?

Would you explain anything differently?

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This video is from the free online course:

Teaching Primary Science: the Solar System and Beyond

Royal Observatory Greenwich

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