Scientists have solved the mystery of Jupiter’s polygon storms, which were first spotted by NASA’s Juno space probe in 2019.
At the gas giant’s south pole, hidden from view from Earth, is a herd of storms arranged in a perfect geometric pattern.
This is unlike anything else humanity has observed in the universe. The most comparable gas giant we know of, Saturn, has single massive storms at each of its poles – not a collection of them arranged in such a mathematical formation.
But a research team at the California Institute of Technology, working in the Andy Ingersoll laboratory, has now figured out why the storms arrange themselves in this pattern.
The answer – published in the Proceedings of the National Academy of Sciences – was inspired by a mathematical proof developed long before the space age – and almost 150 years ago by the British mathematical physicist and engineer Lord Kelvin.
Working alongside American physicist Alfred Mayer, he observed in 1878 that when circular magnets were floated in a pool of water, they would spontaneously arrange themselves into geometric shapes.
“Back in the 19th century, people were thinking about how spinning pieces of fluid would arrange themselves into polygons,” Professor Ingersoll said.
“Although there were lots of laboratory studies of these fluid polygons, no one had thought of applying that to a planetary surface.”
This is what the scientists at Ingersoll’s laboratory did, building a computer model of what might be happening on Jupiter and running the simulations to see if their model held any value.
The storms are very similar to those on Earth, which form close to the equator and drift towards the poles – but on Earth the hurricanes and typhoons tend to dissipate when they get too far away from the equator.
However, because Jupiter’s storms do not experience any friction from the land or the oceans, they keep on going until they reach the poles.
In the early trial runs of the simulations, the team found that the cyclones tended “to merge at the pole due to the rotation of the planet” said Dr Cheng Li, lead author of the study and a researcher at UC Berkeley.
But they found that the stable geometric arrangement could occur when the storms were each surrounded by a ring of winds turning in the opposite direction to the storms themselves, called an anticyclonic ring.
The made the storms repel each other rather than merge.
This phenomenon could help researchers understand how Earth’s weather behaves – but also solves a particularly fascinating and modern mystery.
“Other planets provide a much wider range of behaviours than what you see on Earth, so you study the weather on other planets in order to stress-test your theories,” Professor Ingersoll said.