After traveling through the mantle, you reach Earth’s core. The core is made mostly of the metals iron and nickel. It consists of two parts—a liquid outer core and a solid inner core. Together, the inner and outer core is 3,486 kilometers thick.
The main component of the outer core is iron, and its density is considerably lower than that of pure iron, it was thought to contain a large number of light elements like hydrogen and oxygen.
Distinguishing the type and amount of these light elements will take into consideration a superior comprehension of the origin of the Earth, explicitly the materials that made up the Earth and environment at the core when it isolated from the mantle. In any case, this initially requires an exact estimation of the density of pure liquid iron at extreme pressure and temperature like the molten core so that densities can be compared.
With rising pressure, the melting point of iron also increases. And, this makes it difficult to examine the density of liquid iron under ultra-high pressure. Previous high-pressure liquid iron density measurements claimed that it was about 10% higher than the density of liquid iron under core conditions. Still, the shock compression experiments used were assumed to have a significant error.