Scientists have recreated in the lab some of the wild weather that might be found on Jupiter and Saturn. Using extremely high pressures and laser shock waves, the researchers produced “helium rain” which has been hypothesized to fall on these planets.
The atmospheres of gas giants, like Jupiter and Saturn, are made up mostly of hydrogen and helium. Under those conditions, it’s long been predicted that helium should form liquid droplets and fall, but experimental evidence had proven tricky to track down.
But now, those conditions have been recreated in the lab, producing helium rain with it. It’s thanks to researchers at the University of Rochester, UC Berkeley, Lawrence Livermore National Lab, and the French Alternative Energies and Atomic Energy Commission.
The team first used a diamond anvil cell to compress a mixture of hydrogen and helium to about 40,000 times the pressure of Earth’s atmosphere. Then, the researchers fired a high-powered laser at the gases, producing strong shockwaves that compressed them even further, as well as heating them to between 4,425 °C (8,000 °F) and 9,925 °C (17,900 °F).
And sure enough, when the researchers studied the reflectivity of the signal it showed indications that its electrical conductivity was changing quickly at certain points. That means the helium and hydrogen were separating, resulting in the helium clumping together into droplets within the hydrogen. Being slightly heavier, these droplets would then sink through the atmosphere like rain – just as predicted.
“Our experiments suggest that deep inside Jupiter and Saturn, helium droplets are falling through a massive sea of liquid metallic hydrogen,” says Gilbert Collins, lead author of the study. “That is a pretty amazing thing to think about next time you look up at Jupiter in the night sky. This work will help us better understand the nature and evolution of Jupiter, which is particularly important as Jupiter has long been thought to have been somewhat of a space trash collector – protecting our planet in the solar system.”
Helium isn’t the only unusual thing to fall as rain in the atmospheres of other planets. Astronomers have previously found evidence of extraterrestrial rain made of rocks, diamonds, rubies, iron, or titanium oxide.
The new study was published in the journal Nature.
Source: University of Rochester
