Modern Theory:
History of Study:
Earth's Layers:
Earth's Crust:
Upper Mantle:
Lower Mantle:
Outer Core:
Inner Core:
The temperature of the inner core is estimated to be about 5,700 K (~5,400 °C; 9,800 °F). The only reason why iron and other heavy metals can be solid at such high temperatures is because their melting temperatures dramatically increase at the pressures present there, which ranges from about 330 to 360 gigapascals.