Hurrah, this brings us to the end of the module. We had begun the module by talking about the Earth's inner core, which is made of an iron-nickel mixture. Even though the inner core's temperature 5500 °C is more than the melting point of the iron-nickel mixture, the mixture is in the solid state.

The mixture remains a solid due to the extremely high pressure in the inner core. The pressure in the inner core is about 36 lakh times the pressure we experience on the Earth's surface!

We learnt earlier that increasing the pressure on a gas converts it into a liquid. Similarly, increasing the pressure on a liquid turns it into a solid. This is why the inner core remains in a solid state, despite very high temperatures.