The CORE is the central part of the Earth, which is composed of a solid inner layer and a liquid outer layer. It is made up of iron and nickel and is about 2, 900 km thick. The CORE is the hottest part of the Earth, with temperatures reaching up to 5, 400°C. It is also the densest part of the Earth, with a density of up to 13 g/cm3. The CORE is responsible for the Earth's magnetic field and plays an important role in the Earth's geology.