The third layer of the of the earth is the outer core. This layer is around 2300 kilometres thick. It is a liquid layer composed of iron and nickel. This far down in the earth the temperatures are very high this layer of the earth is around 4000-5500 degrees Celsius. If this outer core wasn't there, the earth would be different place because the metals ( iron, nickel) in the liquids form the earths magnetic field and if this was not there, one we would be able to use compasses but the big impact would be that we would have no protection from harmful radiation from space.