It rains solid di­a­monds on Uranus, Nep­tune

Ex­treme pres­sures in re­gion might split mol­e­cules.

The Palm Beach Post - - HURRICANE IRMA - By Sarah Kaplan

Con­sider this your daily re­minder that the so­lar sys­tem is even more awe­somely 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 in the jour­nal Na­ture Astro­physics, re­searchers say they were able to pro­duce this “di­a­mond rain” us­ing fancy plas­tic and high-pow­ered lasers.

“Pre­vi­ously, re­searchers could only as­sume that the di­a­monds had formed,” lead au­thor Do­minik Kraus, a physi­cist at the Helmholtz Dres­den-Rossendorf re­search cen­ter in Ger­many, told the mag­a­zine Cos­mos. “When I saw the re­sults of this lat­est ex­per­i­ment, it was one of the best mo­ments of my sci­en­tific ca­reer.”

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 plan­ets’ 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 ab­surd in­ten­sity, Kraus and his col­leagues used two types of laser — one op­ti­cal, one X-ray — to pro­duce shock waves. Th­ese waves were then driven through a block of poly­styrene, a type of plas­tic com­posed of hy­dro­gen and car­bon, just like Uranus and Nep­tune’s 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.

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