How is the Earth Made Up ?

If we could cut it in half , we would find the Earth is rather like an onion , with various layers around a central core.This core , the nucleus, has a radius of 3,500 kilometers.
Around the nucleus is the ‘mantle’, 100 kilometers thick, then the Earth’s crust on which we live.
The various layers are composed of different materials, the temperature increasing the nearer they are to the nucleus.