At Jupiter’s north pole, there is no single eye of a storm.
There are nine of them: one enormous cyclone at the center, with eight more arranged in a ring around it.
Each outer storm measures 2,500 to 2,900 miles across, roughly the width of the continental United States.
A spacecraft in polar orbit watched that formation hold its shape for years, and what keeps it together is not a solid thing at all.
So what stops eight enormous cyclones from crashing into each other or drifting apart?
Why a displaced storm fights its way back
Each cyclone tends to creep toward the pole on its own, through a process called beta drift, the interaction between the Coriolis force and the storm’s own circular wind pattern. That crowds the storms together near the pole, where the spin of each one begins to act on its neighbors. When a cyclone is nudged out of position, the balance of those forces changes and pushes it back toward where it started.
Yohai Kaspi, a Juno co investigator, has described the cyclones as bouncing off one another in a manner reminiscent of springs in a mechanical system. Nothing physical connects these storms. The restoring force lives entirely in Jupiter’s fluid atmosphere, on a planet with no solid surface and nothing to anchor a storm.
The geometry that looks carved is negotiated continuously by eight moving storms brushing against each other’s edges. Near the pole’s center turns one enormous cyclone, and around it the eight outer storms form an approximate octagon made from weather rather than fixed boundaries.
What the spacecraft actually measured, pass by pass
Infrared composites from the JIRAM instrument aboard Juno show the central cyclone and its eight companions as enduring features rather than transient weather. The mission tracked the same system in visible light with JunoCam on close passes, building a record of where each storm sat from one flyby to the next.
Winds inside the jupiter polar cyclones reach speeds as great as 220 miles per hour, and the storms sit so close that the spiral arms of neighbors come into contact. JIRAM reads the heat radiating up through the cloud tops, which maps storms that sunlight never reaches during polar winter. In those composites the colors stand for radiant heat: thinner yellow clouds register about 9 degrees Fahrenheit in brightness temperature, and the thickest dark red ones sit near minus 181 degrees Fahrenheit.
A still image makes the formation look locked in place. Years of observations show otherwise: each storm oscillates around a preferred position while the whole group drifts slowly westward around the pole, and the octagon holds anyway.
Nine years of flybys and the findings they produced
Juno entered orbit around Jupiter on July 4, 2016, and its extended mission ran through September 2025, giving the team roughly nine years of polar passes. Scientists described a new model of the fast moving jet stream that encircles the north pole, and reported for the first time the subsurface temperature profile of Io, Jupiter’s volcanic moon, a result drawn from the same close passes.
Earth based telescopes view Jupiter from near its equatorial plane, and earlier encounters from Pioneer, Voyager, Galileo and New Horizons gave poor direct views of the poles. Juno’s polar orbit changed that entirely.
The south pole tells a different story. A central cyclone there is encircled by five circumpolar storms in a pentagon, and a sixth was spotted joining that ring in November 2019, with later observations again reporting five. Same planet, two poles, two different arrangements.
The comparison that makes the scale land
A reader who has seen a hurricane photo from orbit has a starting point. Jupiter’s polar cyclones behave something like hurricanes on Earth but on a far larger scale, and unlike terrestrial storms they stay confined to the polar region instead of forming in isolation at lower latitudes. The northern outer storms run 2,500 to 2,900 miles wide, while the five southern ones are larger still, at 3,500 to 4,300 miles.
That tight packing matters. The storms are so densely spaced that neighboring storm walls touch, and the closer they crowd, the stronger the restoring force when one drifts out of line.
Alberto Adriani, the Juno co investigator who led the first published description of the clusters, said of the polar storms: “There is nothing else like it that we know of in the solar system.” The spring like behavior explains the stability, but it raises a harder question immediately.
What the octagon still does not explain
A vorticity based analysis by Juno scientists does predict the numbers. Published work in Nature Geoscience reproduces the latitude and the count of circumpolar cyclones at each pole from the size and spin of the central polar cyclone, and it also predicts that Saturn cannot currently hold such a ring. What that analysis does not settle is how the clusters assembled in the first place, or why the southern count has wavered.
That gap is where the work now sits. The extension that carried Juno’s polar campaign expired at the end of September 2025, and NASA has not publicly confirmed whether the spacecraft has operated since. Its orbit shifted slightly with each pass, handing the team a new angle on the same object that no previous flyby could deliver.
The octagon keeps turning, the archive keeps being worked through, and the question of how such a ring builds itself remains open.
