It's important to note that the core is actually divided into two parts:

* Outer core: This is a liquid layer, extending from about 2,900 kilometers to 5,150 kilometers (1,802 to 3,200 miles) deep. It's primarily made of iron and nickel, with some sulfur and silicon.

* Inner core: This is a solid sphere at the Earth's center, extending from about 5,150 kilometers to the Earth's center at 6,371 kilometers (3,200 to 3,959 miles). The intense pressure at this depth is what keeps the iron and nickel solid, despite the extreme heat.