Question

Why is the inner core of the Earth solid?

Answer 1

The core of the Earth is made up mainly of iron, in an outer liquid layer and an inner solid layer. The outer core is where the circulating conducting liquid generates the geodynamo, responsible for our magnetic field.

Answer 2

The inner core is indeed hotter than the outer core. However, the PRESSURE on the inner core is greater than the pressure on the outer core and the melting point of iron, the main constituent of the core, INCREASES as the pressure goes up. So, because the pressure effect overrides the temperature effect, the inner core is solidified.