What is the earth's core temperature?
The inner core of the Earth is a large sphere of nickel-iron alloy. Surrounding this is the molten inner core which has a temperature of approximately 5400 ℃.

The source of heat that keeps the Earth's core hot and molten is the decay of radioactive elements, predominantly uranium, thorium and potassium.

The Mantle and Crust act as insulators for the Earth's Core.