The centerpiece of the experiment was a new X-ray technique that takes measurements faster than before. Iron samples compressed in the laboratory typically last for only a few seconds, making it difficult to determine in previous experiments if the iron is still a solid, or if it is starting to melt.
The technique makes use of diffraction that occurs when X-rays, or other forms of light, hit an obstacle and bend around it. Scientists sent X-ray bursts at the sample and observed the "signature" of heating, which is a diffuse ring, that pinpointed the temperature.
These experiments pegged the melting point of iron at 4,800 C (about 8,700 F) at a pressure of 2.2 million times that is found on Earth's surface at sea level.
Extrapolating from that measurement, scientists estimated the boundary between Earth's inner and outer core is a searing 10,832 F, give or take about 930 degrees, at a pressure of 3.3 million atmospheres (or 3.3 million times the atmospheric pressure at sea level).
Participating organizations in the experiment include CEA (a French national technological research organization), the French National Center for Scientific Research (CNRS) and the European Synchrotron Radiation Facility (ESRF).