The hottest place on Earth is in its molten core, where temperatures reach approximately 10,800 degrees Fahrenheit. The surface temperatures on the planet vary widely, but according to NASA, the average surface temperature of the Earth is about 59 degrees Fahrenheit.
The Earth's core is this hot because of three primary factors. The first is the radioactive decay that occurs from some of the elements in the core. The second factor that heats the core is the friction caused by the movement of the core. Finally, some of the heat is actually left over from the initial formation of the planet itself, according to Smithsonian.com.