Here's why:
* Crust: The Earth's outermost layer, relatively thin and cool compared to the other layers. Temperatures range from near freezing to around 1000 degrees Celsius.
* Mantle: This thick layer is responsible for plate tectonics and is incredibly hot. Temperatures range from about 1000 degrees Celsius at the top to around 4000 degrees Celsius at the core-mantle boundary.
* Outer Core: Liquid iron and nickel, incredibly hot, with temperatures reaching around 5500 degrees Celsius.
* Inner Core: Solid iron and nickel, under immense pressure, with temperatures estimated at around 5200 degrees Celsius.
While the exact temperature of the mantle varies depending on depth, 2000 degrees Celsius is a good general estimate for the upper mantle region.
