It Rains Diamonds on Uranus and Neptune, New Study Tells Us How

Uranus and Neptune are raining diamonds deep within their hearts, as new evidence has shown the intense pressure and heat thousands of kilometers below their surface can split hydrocarbon compounds and compress carbon into diamonds while sinking deeper towards their cores.

This new study was published in the journal Nature Communications. It used the LCLS X-ray laser (or Linac Coherent Light Source laser) from the SLAC National Accelerator Laboratory to precisely measure how the process involved in 'diamond rain' occurs. Their results showed that carbon directly forms into crystal diamonds.

The study produced data regarding an event that is hard to put into computational models: the two elements' miscibility, or the means by which they are combined, according to Mike Dunne, LCLS director, and plasma physicist. He said that the study showed how two elements separated, much like separating the vinegar and oil in mayonnaise.

Of all the planets in the entire solar system, Uranus and Neptune are the least understood. Their location is too far, and only the Voyager 2 space probe was able to get close for a flyby.

Ice giants such as these planets are very common in our galaxy, says NASA. Exoplanets such as Neptune are more common by a factor of 10 than planets similar to Jupiter. Thus, understanding these ice giants is crucial to understanding the planets in the Milky Way. To get a better sense of these planets, we have to find out what is happening beneath their surfaces.

Their atmospheres are known to be composed of helium and hydrogen, plus methane in lesser amounts. Beneath these layers lies a superdense and superhot fluid composed of 'icy' water, ammonia, and methane that envelops the core.

Past models and experiments suggested and showed that methane could break down and form diamonds from pressure and heat.

The team first pressurized and heated hydrocarbon polystyrene to replicate methane and the conditions inside the planets. The material was bombarded with optical laser pulses, heating it to roughly 5,000 degrees and creating intense pressure. Then 1.5 million bars were produced to exert pressure.

The team measured how the X-rays scattered the polystyrene electrons so that they can observe carbon conversion into diamond, and how the rest of the material splits into hydrogen. For the ice giants, the team now knows that carbon forms diamonds almost exclusively upon separation, and does not undergo a transitional fluid form.

It is an important detail because Neptune is unusually hotter, giving off more than two and a half times the energy than it absorbs from our sun. If dense diamonds are raining into its interior, then they may release gravitational energy that produces heat as the diamonds cause friction from contact with materials surrounding them.

The study has shown how to probe inside the planets in our solar system and let researchers measure other processes that are hard to recreate. As an example, scientists can determine how helium and hydrogen can separate and mix under certain conditions.

The study paves the way for studying planets' and planetary systems' evolutionary histories. In addition, the study can help support experiments concerning the discovery of future sources of energy derived from fusion.