Where it rains solid diamonds
Consider this your daily reminder that the solar system is even more bonkers than you realized: On Uranus and Neptune, scientists forecast rain storms of solid diamonds.
The gems form in the hydrocarbon-rich oceans of slush that swath the gas giants’ solid cores. Scientists have long speculated that the extreme pressures in this region might split those molecules into atoms of hydrogen and carbon, the latter of which then crystallize to form diamonds. These diamonds were thought to sink like rain through the ocean until they hit the solid core.
But no one could prove that this would really work — until now. In a study published this week in the journal Nature Astrophysics, researchers say they were able to produce this “diamond rain” using fancy plastic and high-powered lasers.
“When I saw the results of this latest experiment, it was one of the best moments of my scientific career,” said lead author Dominik Kraus.
Scientists have tried to do this before — who wouldn’t want to make it rain precious stones? — but they ran into problems mimicking the incredible pressures near the gas planet’s cores. Neptune and Uranus are 17 and 15 times the mass of Earth, respectively, and their oceans are crushed by pressures millions of times more intense than the air pressure at Earth’s sea level.
To match this intensity, Kraus and his colleagues used two types of laser — one optical, one X-ray — to produce shock waves. The waves were then driven through a block of polystyrene — a type of plastic composed of hydrogen and carbon, just like the planets’ oceans.
“The first smaller, slower wave is overtaken by another stronger second wave,” Kraus explained in a news release. The combination of the two waves squeezed the plastic to 150 gigapascals of pressure — more than exists at the bottom of Earth’s mantle — and heated it to more than 8,500 degrees. At that moment, the diamonds began to form. The process lasted only a fraction of a second, and the diamonds were no bigger than a nanometre. But Kraus believes the diamonds that develop on Uranus and Neptune are probably bigger and longer-lasting.
“In the planet you have years, millions of years, and a long range of conditions where this actually can happen,” co-author Dirk Gericke, of the University of Warwick, told the Guardian.