Scientists have taken the temperature of Earth's innards, more than a thousand miles beneath the surface, and found that the mercury there soars to about 6,650 degrees Fahrenheit.
That's nearly as steamy as our sun, where the surface reaches 9,980 degrees.
The findings, detailed in the March 30 issue of the journal Science, will help geologists as they seek to understand how heat is transferred through the planet's interior, which drives all geologic processes like earthquakes and volcanoes, and Earth's magnetic field.
The new temperature measurements will also help geoscientists refine their understanding our planet's magnetic field, which protects us from cosmic rays and solar storms. The field fluctuates over time, for reasons not fully understood, and now and then it even shrinks to zero before flipping polarity entirely.
"We know the Earth's magnetic field is generated and maintained in the liquid outer core of the Earth where you basically have rapid flow of metallic iron," van der Hilst said. Since iron is charged, the swirling iron mix sets up an electric field that gives rise to Earth's magnetic field.
The turbulent flow is the result of convection, and a higher rate of heat loss indicates more convection and a faster flow. With computer simulations, scientists have estimated the amount of energy needed to maintain the magnetic field. But this study is arguably the first to nail down concrete estimates, not computer-modeled ones, of these temperatures, van der Hilst said.
"The heat flow that we measure is larger than what is needed to drive the geo-dynamo, so there is actually more energy down there than people thought," van der Hilst told LiveScience.
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