How Hot Is the Center of the Earth? Why Is It So Hot?

(Last Updated On: June 16, 2020)
How Hot Is the Center of the Earth?

If we were to take a journey through Earth’s outer crust, we’d plunge past layers of rock and dirt, through the Earth’s mantle and into its outer core. If we went far enough, we’d reach the center of Earth, the inner core. Earth’s core is the hottest place on the planet, and among the hottest places in the solar system. So just how hot is the center of the Earth?

How Hot Is the Center of the Earth?

The sheer size and scale of the Earth make it difficult for scientists to actually measure the temperature of Earth’s core. We can go to the moon or the bottom of the ocean. We can’t go to the center of the Earth. Why not? Well, the core is about 2,900 kilometers (1,802 miles) below Earth’s surface. The deepest humans have dug is a meager 12 kilometers (7.5 miles).

Further reading: How Deep is the World’s Deepest Hole?

Thus, we have no direct evidence about the composition of the inner core. Based on the prevalence of various chemical elements in the Solar System and the theory of planetary formation, however, researchers have come to widely believe the inner core consists of an iron–nickel alloy. And that it’s primarily solid.

Given what we know about the properties of iron then, scientists have come to various estimates about the temperature of the center of the Earth. According to current research, the temperature of Earth’s inner core is approximately 5,700 K (that’s 5,430°C or 9,806°F). And believe it or not, this is about the same temperature as the surface of the Sun!

Why Is the Center of Earth so Hot?

The Earth’s inner core has three main sources of heat. First, there is heat left over from when the planet formed and accreted. Earth is actually really bad at getting rid of heat, so much of the primordial heat from when the core first developed has been retained. Earth’s tectonic plates essentially act as a blanket on the interior.

Another source of internal heat comes from friction. As dense iron-rich material descends to the core, heat is released. And finally, there is heat from the decay of radioactive elements.

So basically, the Earth has all this heat, and no good method of cooling. So the center of the Earth remains quite hot!

Test your knowledge of the Solar System with this quiz. 

Okay, so you know how hot the center of the Earth is. If you found this interesting, you might also like these astronomy articles. 

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Mark Heald is the Managing Editor of He enjoys spending time with his family, traveling, and bemoaning the fact the Sonics left Seattle.