Earth has a diameter of about 12,756 km (7,972 mi). The Earth’s interior consists of rock and metal. It is made up of four main layers:
1) the inner core: a solid metal core made up of nickel and iron (2440 km diameter)
2) the outer core: a liquid molten core of nickel and iron
3) the mantle: dense and mostly solid silicate rock
4) the crust: thin silicate rock material
The temperature in the core is hotter than the Sun’s surface. This intense heat from the inner core causes material in the outer core and mantle to move around.
The movement of material deep within the Earth may cause large plates made of the crust and upper mantle to move slowly over the Earth’ssurface. It is also possible that the movements generate the Earth’s magnetic field, called the magnetosphere.http://rst.gsfc.nasa.gov/Sect16/Sect16_1.html