Lasers and polystyrene prove that outer planets can produce diamonds
Giving new meaning to the term “Ice Giants,” researchers have confirmed that Uranus and Neptune are likely producing massive diamonds on a regular basis. The frigid planets may be loaded with frozen hydrogen, helium, water and ammonia, but atmospheric conditions can still scrape together enough carbon, heat and pressure to create millions of carats of solid diamonds. Aside from further embarrassing the lie that diamonds are a rarity, understanding how the outer planets make their bling may help us analyze new exoplanets in other solar systems.
The key ingredients for the formation of a diamond are carbon, heat and pressure. The carbon should be as homogeneous as possible, lest you end up with a muddled mess of coal containing everything from oxygen to arsenic that ruins the diamond’s perfect structure. The heat and pressure need to be applied together, crushing the carbon atoms into a nice, tetrahedral lattice. On Earth, these conditions are most likely to be met deep in the ground, or possibly in a lab in California.
In the SLAC National Accelerator Laboratory, researchers used a laser to recreate some of the conditions we know exist within Uranus and Neptune, with the expectation that it would be enough to create some diamonds. The source material was a piece of polystyrene, as the plastic’s carbon and hydrogen are a good proxy for the methane found on the ice giants. With a good zap from an optical laser, overlapping shock waves were created in the polystyrene, briefly creating conditions hotter than 8,500° Fahrenheit with 145,038 pounds of pressure per square inch.
Dainty diamonds, distant worlds
This intense moment was barely a moment though. The shock waves existed so briefly that an x-ray laser operating on a femtosecond timescale was needed to document the process. The resulting diamonds were tiny too, reaching only a few nanometers across. However, scaling this process up to the size of a planet like Uranus or Neptune should give a much more dazzling result, with massive diamonds being created in the planets’ liquid mantles before settling near their rocky cores.
With these calculations in hand, scientists hope to improve our estimates about exoplanets with similar compositions. Beyond the radius and mass that we can now estimate, knowing what reactions and activity are happening in a distant planet’s interior would help explain everything from their weather patterns to the exact coloration of their atmospheres.
Source: The Forecast on Neptune? Diamond Rain by Nathaniel Scharping, D-brief
