The Earth's inner core was once liquid, but has turned solid over time. As the Earth gradually cools, the inner core expands outwards at the surrounding iron-rich liquid "freezes." That said, it ...

The Earth's interior is composed of four layers ... in diameter. Although this inner core is white hot, the pressure is so high the iron cannot melt. The iron isn't pure—scientists believe ...

Geophysicists studying seismic waves from earthquakes have found evidence suggesting that Earth's inner core not only rotates differently but also changes shape. Analysis of earthquake waveforms ...