Scientist have come to realize that there are the mantle, the core and the crust.
The inner part of the earth is about 1,800 miles (2,900) below the earth surface. The core is a dense ball of the elements iron and nickel. It is dividing into two layers, the outer core and the inner core. The inner core, the center of earth, is solid and about 780 miles thick. The outer core is so hot that the metal is always molten. The inner core pressures are so great that it cannot melt, even though temperatures there reach 6700F. The outer core is about 1,370 miles thick. Because the earth rotates, the outer core spins around the inner core and that causes the earths magnetism.
Magnetism has been used by sailors to find their way on earth for thousands and thousands of years. Magnetism also influences electro particles outside the atmosphere of the earth, up to more than 37,000 miles into space
http;// mediatheek. Thinkquest.nl/~11125/en/core. htm
image by Colin Rose, Dorling Kindersley