Not even the imaginative Jules Verne could guess that hea temperature near the center of the Earth would be close to 6000 degrees Celsius, that is, 1000 degrees warmer than what was estimated in a previous experiment carried out 20 years ago. The new measure, released today in the prestigious magazineScience, confirms geophysical models that indicate that the temperature difference between the solid core of the Earth and the mantle that surrounds it must be at least 1,500 ºC to explain why our planet has a magnetic field.
The core of the Earth is essentially composed of airon sphere at temperatures above 4,000ºC and pressures exceeding 1.3 million atmospheres. Under these conditions, iron is as liquid as ocean water. And only in the center of the Earth, where the pressure and temperature rise are even higher, does liquid iron solidify. Analysis of seismic waves caused by earthquakes passing through the earth’s crust reveals the thickness of these cores, as well as how pressure increases with depth. But it does not allow to calculate the temperature.
To find out this measure (without descending, of course, to the center of the Earth), a group of scientists from the French national organization for scientific research (CEA) carried out a series of experimentswith iron subjected to high pressures with the help of X-ray technology. In this way they determined that the melting point of iron exceeds 4,000 degrees (under the pressure of 2.2 million atmospheres). Since the pressure at the boundary between the liquid and solid core of the Earth is3.3 million atmospheres, the temperature in these conditions would be around 6,000 degrees.
