How do we know when a rock is from space? © Alamy

How do we know when a rock is from space?

Get your magnets out folks and start scavenging for meteorites.

Asked by: Susie Haynes, Liverpool

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The first thing you’ll need is a magnet. Almost all meteorites are rich in iron so they’ll stick to magnets. But there are plenty of terrestrial stones that will pass this test too.

Next, you’ll need to see if the rock’s surface looks like it burnt or melted as it passed through the atmosphere: does it have a burnt black crust or flow lines where rivulets of molten rock ran over the surface?

If everything checks out so far, then you’ll have to get a lab to test for nickel content. Virtually all meteorites contain significant amounts of nickel, which is an element that is fairly rare on Earth.


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