As a geologist with a focus on Earth's interior dynamics, I can explain the reasons behind the high temperatures found at the core of the Earth. There are three primary sources of heat that contribute to this phenomenon: 1. Primordial Heat: The Earth formed approximately 4.6 billion years ago from the gravitational accretion of dust and gas. During this process, kinetic energy was converted into heat, and some of this heat has been retained within the Earth's interior to this day. 2. Frictional Heating: The movement of solid and molten iron within the core generates heat through friction. As denser materials sink towards the center, this process, known as convection, creates additional heat. 3. Radioactive Decay: The natural decay of radioactive isotopes within the Earth's mantle and core releases heat. This heat is a significant contributor to the overall temperature of the Earth's interior. These sources of heat have kept the Earth's core at a temperature estimated to be between 4,000 and 6,000 Kelvin (3,725 to 5,725 degrees Celsius or 6,725 to 10,325 degrees Fahrenheit). read more >>

There are three main sources of heat in the deep earth: (1) heat from when the planet formed and accreted, which has not yet been lost; (2) frictional heating, caused by denser core material sinking to the center of the planet; and (3) heat from the decay of radioactive elements.read more >>