For years people belived it was flat. People also believed Earth was the center of the universe and that sea monsters existed. Some thought the Earth was hollow and some thought it was just a solid rock. People believed alot of things and they still do. Science has provided some answers though. Scientists have been studying the Earth and they have learned many things. Most importantly, they have learned the Earth is Dynamic.
The Earth is about 12,750 kilometers (km) in diameter and and is layered like an onion. In fact, a more appropriate comparison would be with a hard-boiled egg. Earth is made up of four main layers: the crust, the mantle, the inner core and the outer core. The crust of the Earth is much like the shell of an egg. It is very thin and brittle. It breaks easily and when this happens there is an earthquake. The mantle is a lot like the egg white and the core like the yolk.
