Book 24, Question 6
Why does it get hotter the deeper you go underground?
Earth's center is very hot, and its heat slowly flows outward. As you go deeper, you get closer to that heat. In most places, the temperature goes up by roughly 1 degree Fahrenheit for every 70 feet down. That is why deep mines need cooling and why the bottom of a very deep hole is so hot.
More fun facts
- In most places, the rock and soil get about 25 degrees Celsius hotter for every kilometer you go down.
- That is roughly 1 degree Fahrenheit warmer for about every 70 feet of depth.
- Most of Earth's inside heat comes from radioactive elements, such as potassium-40 and thorium-232, slowly breaking down.
- Some of the heat is left over from when Earth first formed out of crashing space rocks.
- The inner core is about 5,200 degrees Celsius, far hotter than any oven.
- Earth has been giving off heat for about 4.5 billion years and will keep doing so for billions of years more.
Sources: National Geographic Education, National Geographic Education
Questions kids ask
Is the center of the Earth as hot as the Sun?
Part of the core reaches about 6,000 degrees Celsius, which is about as hot as the surface of the Sun.