People often talk about it "raining money" or getting "pennies from heaven." In reality, if riches did fall from the sky, you'd be too busy running for your life to appreciate your good fortune. That's exactly what happens on Uranus and Neptune, two of the most mysterious planets in our solar system. Scientists say that they have solid diamond rain.
You Can Stand Under My Umbrella
The first thing you notice about Uranus and Neptune is that they're blue. That comes from the fact that along with hydrogen and helium, their atmospheres have large amounts of methane. Scientists think that when lightning storms strike clouds of methane (good ol' CH4), carbon atoms break away from their chemical bonds and float through the air by themselves. These lonely carbon atoms begin to collect in clouds of soot that sink into the lower reaches of the atmosphere, where the pressure and temperature around them steadily rises. Eventually, the forces become so great that the carbon atoms squeeze into solid diamond. Boom, diamond rain.
There's enough methane on our solar system's other gas giants, Saturn and Jupiter, to make it rain diamonds there too. But methane makes up a much larger percentage of the atmosphere on our blue neighbors — so much that scientists think diamond oceans dotted with solid diamond "icebergs" on Uranus and Neptune could be to blame for the fact that their magnetic fields are tilted from their axes of rotation by a whopping 60 degrees.
Make It Rain
Of course, this is all theoretical. We've never actually dived into the atmosphere of Uranus or Neptune, so we don't know from experience if it actually rains diamonds. That's why a study published in August 2017 in the journal Nature Astronomy is so exciting: it represents the first time scientists have recreated the conditions on Uranus and Neptune to successfully produce diamond "rain."
Using what's called the Matter in Extreme Conditions (MEC) instrument at Stanford University, scientists used an X-ray laser to blast a type of plastic made up of the same carbon and hydrogen atoms present in the atmospheres of the gas giants. All that energy forced the carbon atoms to dissociate from the plastic and combine into super tiny diamonds. The diamonds only lasted for a nanosecond, but that was enough for the researchers to prove it could happen.
That's exciting for our knowledge of our planetary neighbors, but it could have Earth-based benefits as well. Nanodiamonds have applications in things like medicine, and right now we can only make them with controlled explosions. This could be a safer and more efficient way to produce those tiny diamonds for those purposes.