How can I use meteorites to teach Earth's layers?

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Iron meteorites model Earth's metal core, pallasites the core-mantle region and stony meteorites the mantle and crust, helping pupils understand layers they can never visit.

Pupils often learn that Earth has a crust, mantle and core, but it can be hard to understand how we know. Meteorites help.

Differentiation. Explain that when young planets and some asteroids were hot enough to melt, heavy metal sank to the centre to form a core, while lighter rock floated upwards, forming a mantle and crust. This is called differentiation. It is like a mixture of oil and water separating when shaken and left to settle.

Meteorite samples. Some asteroids that differentiated were later smashed apart by collisions, scattering pieces of their insides. Meteorites from them include: - Iron meteorites: pieces of metal cores. - Pallasites: a mix of metal and olivine, perhaps from near the core-mantle boundary. - Diogenites and eucrites: rocks from the mantle and crust of the asteroid Vesta.

Comparison with Earth. Earth's core is mostly iron and nickel, like iron meteorites. Its mantle is rich in olivine and pyroxene, like some meteorites. Scientists combine meteorite evidence with seismic waves from earthquakes to understand Earth's interior.

Activities. - Pupils build a model of a differentiated asteroid, with a metal ball bearing core inside clay layers, then 'break it apart' to show how pieces become different meteorites. - Sort meteorite cards into core, boundary, mantle and crust. - Compare a diagram of Earth's layers with Vesta's.

Discussion. Why can we not drill to Earth's core? The deepest borehole reached only about 12 kilometres. Meteorites are the closest samples we have of a planetary core.

How can I use meteorites to teach Earth's layers?

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