The Earth can be divided into three distinct parts; the crust, the mantle, and the core.
The Crust is approximately 5 - 100 km thick and is broken into pieces.
The Mantle contains the Asthenosphere and what scientists call the Moho. The Asthenosphere is the top of the mantle on which the plates of the crust float. Its main characteristic is the property of plasticity. That means that even though it is a solid, it flows like a liquid (think of silly putty). The Moho is the boundary between the crust and the mantle. Scientists don't know alot about it but they do know it is a different type of rock.
The Core is made up of two parts; the Inner Core and the Outer Core. The inner core is approximately 1500 km thick and solid nickel, cobalt, and iron. It is radioactive and because of this, and the fact it is under great amounts of pressure, is extremely hot. The outer core is approximately 2000 km thick and is made mostly of Iron. It is approximately 3800 degrees Celsius.
