An international team of researchers led by Dr. Mungo Frost from the SLAC research center in California has gained new insights into the formation of diamond rain on icy planets such as Neptune and Uranus, using the X-ray laser European XFEL in Schenefeld. The results also provide clues to the formation of the complex magnetic fields of these planets.

In earlier work on X-ray lasers, scientists discovered that diamonds should form from carbon compounds in the interior of the large gas planets because of the high pressure prevailing there. These would then sink further into the interior of the planets as a rain of precious stones from the higher layers.

A new experiment at the European XFEL has now shown that the formation of diamonds from carbon compounds already starts at lower pressures and temperatures than assumed. For the gas planets, this means that diamond rain already forms at a lower depth than thought, and could thus have a stronger influence on the formation of the magnetic fields.

In addition, diamond rain would also be possible on gas planets that are smaller than Neptune and Uranus and are called "mini-Neptunes." Such planets do not exist in our solar system, but they do occur as exoplanets outside of it.