Experiment Supports Theory That 'Diamond Showers' Take Place on Uranus and Neptune

At Stanford University, an international team of scientists finally simulated the "shower of diamonds" that they believe is taking place deep within Uranus and Neptune.

Uranus and Neptune are both classified as "ice giants." Unlike the Earth, their solid cores are likely swathed in thick layers of "ice" made from the combination of water and ammonia.

At a depth of 6,200 miles, researchers speculate that the hydrocarbons encounter so much pressure and heat that the bonds between the hydrogen and carbon molecules are broken. Once free from the bonds, the carbon atoms are compressed into microscopic diamonds, resulting in what can be described as "diamond showers."

Previously, no one had been able to directly observe these sparkling showers in an experimental setting, according to Dr. Dominik Kraus, who is the head of a Helmholtz Junior Research Group at the German research laboratory Helmholtz-Zentrum Dresden-Rossendorf.

But, that was precisely the breakthrough Kraus and his international team have now achieved. In their experiment, polystyrene (a plastic made from carbon and hydrogen) was exposed to a simulation of the immense pressure found deep within Neptune and Uranus. They blasted the plastic with shock waves generated by an optical laser and x-rays.

At a pressure of about 150 gigapascals and temperatures of about 9,000 degrees Fahrenheit, the shock waves compressed the plastic and successfully broke the carbon-hydrogen bonds. The carbon atoms instantly transformed into microscopic diamonds.

"The first smaller, slower wave is overtaken by another stronger second wave," Kraus explained. "Most diamonds form the moment both waves overlap. Our experiments show that nearly all the carbon atoms compact into nanometer-sized diamonds."

Kraus theorized that the cores of Uranus and Neptune could contain "oceans of liquid carbon" with gigantic "diamond icebergs swimming on top of it."

While it's unlikely man will ever have the ability to mine diamonds on these distant planets, the experiments at Stanford are already yielding innovative and efficient ways of producing nano-diamonds — diamonds that may find their way into electronic instruments, medical equipment and cutting devices.

The results of the research were published in the scientific journal Nature Astronomy.

Credit: Illustration by Greg Stewart / SLAC National Accelerator Laboratory.