Earth's Core Temperature A Hellish 6,000 Degrees Celsius, New Study Confirms

A new experiment on the temperature of Earth's core concludes that it's a hellish 6,000 degrees Celsius (10,832 F), a solid 1,000 C (1,832 F) hotter than previously believed when the last temperature model was run 20 years ago.

The measurements confirm the expected temperature gradient between Earth's solid core and the mantle surrounding it and explain why the planet has a magnetic field, according to a statement by the European Synchrotron Radiation Facility.

Earth's core consists mainly of liquid iron, and it is only at the very center of the core, where the pressure and temperature are so extreme that the molten iron solidifies. The temperature difference between the mantle and the core is the main engine for large-scale thermal movements, which coupled with the Earth's rotation, function as a generator for the planet's magnetic field. 

To complete the experiment of Earth core temperature, the research team used a laboratory analysis of melting iron at extreme temperatures and pressures, using x-rays to determine the exact moment the iron transforms from a super-hot liquid to a solid.

"We have developed a new technique where an intense beam of X-rays from the synchrotron can probe a sample and deduce whether it is solid, liquid or partially molten within as little as a second, using a process known diffraction," said Mohamed Mezouar from the ESRF, "and this is short enough to keep temperature and pressure constant, and at the same time avoid any chemical reactions."

The research team determined the melting point of iron up to 4,800 C (8,672 F) and 2.2 million atmospheres pressure, and then used an extrapolation method to determine that at 3.3 million atmospheres, the pressure at the border between liquid and solid core, the temperature would be 6000 C +/- 500 degrees. This extrapolated value could slightly change if iron undergoes an unknown phase transition between the measured and the extrapolated values.

"We are of course very satisfied that our experiment validated today's best theories on heat transfer from the Earth's core and the generation of the Earth's magnetic field. I am hopeful that in the not-so-distant future, we can reproduce in our laboratories, and investigate with synchrotron X-rays, every state of matter inside the Earth," said researcher Agnès Dewaele.

The results of the study are published in the journal Science.