Question: what is the earth made up of

Natalie Garrett answered on 13 Nov 2015:

This is an interesting question: it could mean, what elements make up the earth, or it could mean what is the earth’s structure.

In terms of elements, the earth has lots and lots of different elements. If you want a long list of them, check this: https://en.wikipedia.org/wiki/Abundance_of_the_chemical_elements#Earth.27s_detailed_bulk_.28total.29_elemental_abundance_in_table_form

The most common element on earth is iron, it makes up about 5% of the earth’s crust. The next most common element is oxygen, then silicon, magnesium, nickel, then calcium and so on.

The structure of the earth is pretty cool. The very centre of the earth is the inner core, which is solid and made of iron and nickel with temperatures of up to 5,500°C. The next layer is the outer core, which is also iron and nickel, but this layer is liquid and with similar temperatures. The next layer is the mantle, which is 2,900 km thick, and made of semi-molten rock (magma) – towards the outer edge of the mantle, the rock is hard, but towards the centre it’s soft and starting to melt. The last layer of the earth is the crust, which is a relatively thin layer of solid rock (0 – 60 km thick) which is the bit we live on. It makes me feel very small to think of how big the earth beneath me is!