The Core

The Earth's core has a diameter of 6470km, and a density that ranges from 10g/cm3 to 13g/cm3

No direct measurements or observations have ever been made of the core, and what we know about it comes from careful study of shock waves, meteorites, and other processes within the Earth.

We believe the core is made mainly of Iron and Nickel, and that it is divided into two areas; the outer core and the inner core.

The outer core is almost certainly liquid, the metals being molten because of the very high temperatures. Evidence for this comes from a study of earthquake shock waves. We know that the shockwaves travel at different speeds when they pass through different types of rock, and rocks that are solid, plastic or liquid. The waves show a change in speed as they pass between the inner and outer core, suggesting that the outer area is liquid, and the inner core is solid.

The centre, or inner core is incredibly hot, about 5,000C and subjected to a pressure of about 4 million atmospheres! It is this extreme pressure that stops it from melting and keeps the inner core in a solid state.

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