Scientists Determine Earth's Core is as Hot at Sun's Surface
Posted on April 27, 2013
Scientists have determined that the temperature near the center of the Earth is 6000 degrees Celsius, give or take about 500 degrees. This is 1,000 degrees hotter than previous experiments have suggested. It is as hot as the surface (photosphere) of the sun. This artist's view above shows the different layers of the Earth and their representative temperatures. The Earth's core consists of solidified iron surround by liquid iron.
Scientists say that at temperatures above 4000 degrees and pressures of more than 1.3 million atmospheres the iron near the Earth's center is as liquid as the water in the oceans. The thickness of the solid and liquid cores was determined by analysis of earthquake-triggered seismic waves passing through the Earth.
The seismic waves do not provide us with any information about temperature. Scientists had to conduct an experiment to come up with the core temperature. To look at the melting point of iron at different pressures in the laboratory, scientists used a diamond anvil cell to compress speck-sized samples to pressures of several million atmospheres. They then used powerful lasers to heat them to 4000 or even 5000 degrees Celsius. The scientists determined experimentally the melting point of iron up to 4800 degrees Celsius 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 Celsius +/- 500 degrees.
The research team was led by Agnes Dewaele from the French national technological research organization CEA, alongside members of the French National Center for Scientific Research CNRS and the European Synchrotron Radiation Facility ESRF. Their research was published here in Science.