A diamond rain is gonna fall
An astronomical theory is now backed by laboratory evidence.
Astronomers call it “diamond rain”, but no one has ever seen it – until now.
According to calculations, pressures on the icy giant planets Uranus and Neptune are so great that carbon atoms squeeze tightly together to form diamonds, which then fall through the planets’ softer layers towards their solid cores.
Now scientists using the SLAC National Accelerator Laboratory at Stanford University in California have succeeded in creating the phenomenon – albeit very briefly. A team led by Dominik Kraus from the Helmholtz Zentrum Dresden-rossendorf research centre in Germany subjected a piece of plastic to the intense energy produced by SLAC’S X-ray free-electron laser.
The experiment caused almost all the plastic’s carbon atoms to combine into diamonds a few nanometres wide.
“Previously, researchers could only assume that the diamonds had formed,” Kraus says. “When I saw the results of this latest experiment, it was one of the best moments of my scientific career.”
Astronomers think the forces in the frozen mantles of Uranus and Neptune are so powerful that the diamonds formed could weigh millions of carats. It is possible the solid cores of both planets boast a thick diamond coating.
While the planets have had billions of years in which to create their diamond cargo, the experiment using SLAC lasted a couple of quadrillionths of a second – long enough, nevertheless, for the process to be observed, measured and recorded.
“We can’t go inside the planets and look at them, so these laboratory experiments complement satellite and telescope observations,” Kraus says.
The research, published in the journal Nature Astronomy, provides insights into possible distant planetary processes, but it might also produce benefits here on Earth.
Nanodiamonds are widely used in medicine and industry. Currently they are created using controlled explosions. Using a laser is a more efficient, and much safer, method of manufacture.