Structure and composition of the Earth

The Earth is almost a sphere. These are its main layers, starting with the outermost:

• crust (relatively thin and rocky)
• mantle (has the properties of a solid, but can flow very slowly)
• core (made from nickel and iron)

A cross-section showing the Earth’s structure. The outer core is liquid and the inner core is solid

The radius of the core is just over half the radius of the Earth. The Earth’s atmosphere surrounds the Earth.

The Earth’s crust, its atmosphere and oceans are the only sources of the resources that humans need.