Article by: Andacs Robert Eugen, on 11 September 2022, at 09:49 am Los Angeles time

It could be raining with diamonds on planets across the universe, scientists have suggested, after using ordinary plastic to recreate the strange precipitation thought to form on Uranus and Neptune. 

Scientists have previously theorized that extremely high pressure and temperatures turn hydrogen and carbon into solid diamonds thousands of kilometers below the surface of the ice giants. 

Now, new research published in Science Advances has thrown oxygen into the mix, finding that "diamond rain" maybe even more common than previously thought. 

Ice giants like Neptune and Uranus are thought to be the most common form of a planet outside our solar system, meaning that the diamond shower could occur throughout the universe.

Dominik Kraus, a physicist at Germany's HZDR research laboratory and one of the authors of the study, said that "diamond rain" is very different from rain on Earth. Beneath the planet's surface is thought to be a "hot, dense liquid" in which diamonds form and sink slowly down to potentially Earth-sized rocky cores more than 10,000 kilometers deep, he said. 

There, the diamond sediments could form vast layers that stretch for "hundreds of kilometers or even more," Kraus told AFP. While these diamonds may not be as bright or cut as "a beautiful gemstone on a ring," he said, they were formed by forces similar to those on Earth. 

In order to replicate this process, the research team found the necessary mix of carbon, hydrogen, and oxygen in an easy-to-use source - PET plastic, which is used for everyday food packaging. 

The team pointed a high-powered optical laser at the plastic, and the light allowed them to watch the formation of nanodiamonds - tiny diamonds too small to be seen with the naked eye. 

"The oxygen that is present in large amounts on these planets really helps suck the hydrogen atoms out of the carbon, so it's actually easier for these diamonds to form," added the study coordinator.

The experiment could point to a new way to produce nanodiamonds, which have an increasingly wide range of applications, including drug delivery, non-invasive surgery, and quantum electronics. 

"Laser production could provide a cleaner and more controllable method to produce nanodiamonds," the scientists explained. 

Research into the universe's diamond shower remains hypothetical for now because little is known about Uranus and Neptune, the most distant planets in our solar system. Only one spacecraft - NASA's Voyager 2 in the 1980s - has passed by the two ice giants, and the data it sent back is still used in research. 

A group at NASA, however, has outlined a potential new mission to these planets that could be launched within the next decade.