It's Raining Diamonds on Saturn
The universe can be a violent place, but there's also a lot of beauty to be found, for those who are prepared to look hard enough.
I wrote this piece for a jewellery website last year. They decided not to use it, so I figured the best place to put it would be here.
“On the surface of Saturn there sit pools of liquid diamond” is a sentence that is always going to pique the interest of a jewellery enthusiast, such are the visual connotations that such a mental image immediately summons to mind.
But this isn’t particularly new information within the scientific community. The idea that diamonds rain in space was first postulated more than four decades ago, and new insights into the planets in our solar system have only reinforced the idea that gemstones that we have considered to be magical on this planet for thousands of years could literally fall like rain upon planets which are, in celestial terms, both our relatively close neighbours and so much more distant.
Distance is always relative, and by most reasonable calculations Saturn is a long way away from Earth; 1.3 billion kilometres, or 3,380 times the distance between Earth and the Moon. And should you finally get there, the difference in size and scale would be breathtaking.
Earth could fit inside Saturn 764 times. Its rings alone, mostly made of ice crystals and ranging in size from dust to pieces to the size of a house (but no bigger - they’re so thin that they’re invisible from many viewing angles), are 282,000 kilometres across, or 22 times the diameter of the Earth.
When you get this deep into the solar system, things are different. As a gas-giant, if you try to step out onto the ‘surface’ of Saturn, you’ll fall and keep falling. Saturn is, of course, a gas-giant, and it’s a long way down. It does have a small, rocky core of water, ice and rock, with a mass equal to about 17 Earths, but the majority of what we see when we look at those pictures of it which all seem so familiar is its atmosphere.
Although it may hang in the sky like the most serene of orbs, Saturn’s atmosphere is one of the most violent places in the solar system. Lightning bolts up to 10,000 times the size of anything we see on Earth streak across the clouds, while winds can reach more than 1800 kilometres per hour.
Practically all of it is made up of hydrogen and helium (96.3% hydrogen and 3.2% helium), but not all of it is. Around 0.3% of it is carbon, mostly in the form of hydrocarbons such as methane gas, and lightning storms high up in its ‘thunderstorm alley’ can turn this methane to soot.
That’s where all this violence starts to have an extraordinary and magical effect. The soot starts to harden and fall towards the planet’s rocky core. Under the vast amount of pressure being exuded upon it, by 1,500 kilometres down it’s turning to graphite, similar to the lead in a pencil. By the time it reaches 6,000 kilometres that graphite has hardened further; it’s becoming solid diamond.
Still it falls, and still the pressure weighing upon it from all angles grows. It’s still another 30,000 kilometres to the surface of the inner core itself, and by this point the pressure is so great that the solid diamonds start to liquefy again into what may be rainfall before landing on the rocky surface, where it pools. Some have even suggested that it could form into rivers or even seas, over time. On the surface of Saturn there sit pools of liquid diamond.
It should be added that much of this is theoretical. We can’t see any of it. But the science certainly backs the theory up. Data returned from the Cassini space probe certainly provided a remarkable level of detail in terms of filling in the gaps in our knowledge on this beguiling subject.
Some of these diamonds could be large enough to wear, with the largest about a centimetre in diameter. Around 1,000 tonnes of them a year are formed. It’s even been estimated that between the two gas-giants Jupiter and Saturn, there could be reserves on these cores of 10 million tonnes of diamond.
This phenomenon isn’t exclusive to Saturn, either. Opals were found by the Mars Rover, further adding to the body of evidence indicating that the red planet once had running water. Nanodiamonds, tiny microscopic pieces of diamond formed elsewhere in the universe, have been found in meteorites that have hit the Earth.
The further you go out into the universe the stranger things can become. Towards the outer edge of our solar system can be found Neptune and Uranus, the two ice-giants. That these two planets could have inner cores including diamond was first proposed as long ago as 1981, and again subsequently collated data has tended to back these claims.
The biggest difference between the gas-giants and the ice-giants is that, because Neptune and Uranus are smaller than Saturn–meaning lower, albeit still extremely high, pressure–and because the temperature near the core is substantially lower, there is no rainfall of liquid diamond on Neptune and Uranus, but solid stones landing on the surface. These crystals have been estimated to be as big as a metre wide.
Step outside of our solar system, and things get stranger still. Planets outside our solar system not only experience the same phenomenon, but are believed to do so in far more extreme ways than in our solar system. HAT-P-7b, for example, is an exoplanet–a planet that we’ve observed which exists outside our solar system–around 1,000 lightyears from us. It’s sixteen times the size of Earth, and is understood to have cloud formations made up of corundum, the mineral which forms rubies and sapphires. Even NASA themselves describe HAT-P-7b’s clouds as “likely visually stunning”.
Another which caused particular excitement is an exoplanet orbiting a pulsar in an unknown galaxy almost 4,000 lightyears (about 24 quadrillion miles) from Earth. First discovered in 2011, ‘PSR J1719−1438 b’ might not be the most romantic of names, but it could be one of the most romantic of sights.
Sitting in very close orbit to the pulsar for which it’s named (that ‘b’ on the end of its name matters), this exoplanet is believed to be a carbon planet under pressure so great that the planet itself is entirely crystalline, primarily made up of a diamond-like substance with a greater density than the stone with which we’re familiar. It’s possible that somewhere out there sits a jewel in the sky, glinting in the light of the pulsar which brought it into being and which one day will destroy it.
The universe is a violent but beautiful place. On our tiny blue-green dot, we have attached a value to diamonds for almost 4,000 years, from ancient tribes in India, who refused to cut them because they believed that to do so would lessen their strength, to the first engagement ring proposal in the 15th century and into the 21st century, with the thousands of interpretations of them that we have permeating right the way through our culture. Small wonder then, that as our knowledge of the universe has grown throughout the last century, they should have caused us such new surprises, both within our own solar system and beyond.