Beginning of the Earth
What is the earth like inside?
Essentially, the earth is constructed something like a baseball. If you were to cut a baseball in two, you would see that it has a core of solid rubber. Wrapped around this inner core are a great many layers of heavy string. This string binding is solid, yet it is not as solid as the rubber core, for it will give and sometimes alter its shape under pressure. The outer covering is a thin layer of horsehide which holds in all the rest of the ball.

The solid-rock covering of the earth, called the crust, is between ten and thirty miles thick - much thinner in proportion than the horsehide covering of the baseball.

Under this crust is a thick layer of a different kind of rock, which is known as the earth's mantle. The rock of the mantle is solid, but it is solid in the same way that the string wrapping of the ball is solid. Under pressure it will move slightly and change its shape. The mantle extends to a depth of 1,800 miles.

Enclosed by the mantle is the earth's core. Unlike the centre of a baseball, the centre of the earth is made up of two parts: an outer core and an inner core. Both are composed of metal; mostly iron, with some nickel - but the outer core is liquid and the inner core is solid. At the very centre of the core, the temperature is about 8,000 degrees — not much less than the temperature on the surface of the sun.

The total distance from the earth's surface to its centre averages approximately 3,960 miles.
What is the earth like inside?