Космический аппарат Juno раскрыл тайну «восьмерки» штормов на Северном полюсе Юпитера

Jupiter’s north pole would be difficult to invent from the planet’s familiar face. The orange and white belts vanish into a bluish, turbulent cap. Near its centre turns one enormous cyclone. Around it, eight more form a crowded ring, creating an approximate octagon made from storms rather than cloud boundaries. The outer cyclones are roughly 4,000 to 4,600 kilometres across. Some span more than the distance from London to Baghdad. Winds can reach about 350 kilometres per hour, and the spiral arms of neighbouring storms brush against one another. Yet the cyclone cores do not simply merge into one polar vortex. A still image makes the formation look locked in place. Years of observations from NASA’s Juno spacecraft show otherwise. Each storm wanders around a preferred position while the whole group slowly drifts westward. In an April 2025 presentation of Juno results, mission scientist Yohai Kaspi compared the interaction to masses bouncing against springs. The analogy is useful if it is not taken literally. Nothing solid joins these storms. They are not rebounding from walls. The spring-like behaviour emerges because a cyclone displaced from its usual position changes the atmospheric forces acting on it, creating a tendency to move back. Juno saw a pole hidden from every earlier visitor Earth-based telescopes view Jupiter from close to its equatorial plane. The Pioneer, Voyager, Galileo, Cassini and New Horizons encounters also provided poor direct views of the poles. A globe’s high latitudes are compressed towards the limb when seen from the side, making their weather difficult to map. Juno changed the geometry. After entering orbit in July 2016, it followed elongated paths over Jupiter’s north and south poles. The visible-light JunoCam instrument supplied detailed cloud images, while the Jovian Infrared Auroral Mapper, or JIRAM, detected thermal radiation emerging through the atmosphere and could observe polar structure even in darkness. The first close passes revealed a pattern without an obvious precedent. A 2018 Nature paper described one polar cyclone and eight circumpolar cyclones in the north. In the south, another central cyclone was surrounded by five. The researchers could see the polygons, but did not yet know how they formed or why adjacent storms survived without merging. NASA’s contemporary summary of those first polar results placed the northern cyclones between 4,000 and 4,600 kilometres wide and reported winds reaching 350 kilometres per hour in some polar storms. These are not small vortices decorating a larger circulation. Each is a planetary-scale weather system. Nine cyclones, not one storm with eight arms The north-polar arrangement contains nine distinct cyclone cores. The one near the pole occupies the middle, while eight companions lie in a ring at roughly 84 degrees north latitude. Calling the pattern an octagon refers to the positions of the outer eight, not the shape of a single storm. Each cyclone rotates counter-clockwise in the northern hemisphere. Their outer spiral structures can meet and distort, but recognizable centres remain. This coexistence is unusual because vortices close enough to interact often orbit, deform or merge. Jupiter’s lack of a solid surface also matters. As SpaceDaily explained in its account of why there is nowhere to land on Jupiter, gas becomes progressively hotter, denser and more compressed with depth. The cyclones are circulations inside that continuous atmosphere, not storms sitting above continents or oceans. The word cyclone describes the direction and structure of the rotating flow. It does not mean that Jupiter’s storms work exactly like terrestrial hurricanes. Earth’s tropical cyclones draw energy from warm ocean water and usually weaken over cold water or land. Jupiter supplies no comparable ocean boundary, and heat rising from its interior contributes to its weather. The formation is stable, but it is not stationary Juno returned to the poles repeatedly, allowing researchers to compare the storms over years rather than one flyby. A five-year JIRAM analysis published in 2022 found that the overall northern and southern structures remained almost unperturbed. Many individual cyclones kept recognizable morphologies. The same record showed motion around the apparent order. Cyclones migrated around mean positions on timescales of months. At the south pole, where tracking was initially more complete, the dominant oscillations had periods near 12 months and amplitudes of roughly 400 kilometres. Four hundred kilometres is a large displacement by human standards, yet modest beside a storm several thousand kilometres across. The ring can therefore preserve its broad polygon while every member shifts. Stability here means a persistent configuration, not a frozen map. The group also drifts westward around the pole. Later work represented the cluster’s average motion through a centre-of-mass approach. Individual exchanges partly cancel when the ring is considered as a whole, exposing a slower collective movement beneath the oscillations. Beta drift pulls the cyclones towards the pole A rotating planet gives moving air an apparent deflection through the Coriolis effect. The relevant influence varies with latitude. Because a giant cyclone spans many degrees of a curved planet, one side occupies a different planetary-vorticity environment from the other. That gradient creates what atmospheric scientists call beta drift. The circulation rearranges the surrounding vorticity and develops an asymmetric flow that nudges the vortex. The same broad idea helps explain parts of hurricane motion on Earth, although steering winds and local conditions also matter. Near Jupiter’s poles, beta drift tends to push cyclones poleward and westward. If that were the only influence, the eight surrounding storms would continue towards the central cyclone and crowd together. Their long survival shows that another part of the interaction resists the compression. Each cyclone creates its own vorticity gradients. The central vortex effectively pushes the ring outward, while adjacent ring cyclones push one another apart. A 2021 vorticity-dynamics model used the balance between these influences to predict both the approximate latitude and the number of circumpolar cyclones at Jupiter’s two poles. Why the interaction resembles a system of springs Imagine one of the outer cyclones moving slightly towards a neighbour. Their effective repulsion strengthens as their separation changes. Move it away and the balance with the central cyclone, adjacent storms and beta drift changes in the other direction. Around an equilibrium point, the net influence can behave like a restoring force. That is the spring analogy. A mechanical spring exerts a force that increases with displacement over its useful range. The atmospheric model produces a comparable mathematical relationship near each cyclone’s preferred position. The storms can overshoot, reverse and oscillate without any physical tether. A 2022 study of the oscillatory motion compared forces calculated from the observed locations with the cyclones’ measured accelerations. An idealised model recreated similar oscillations. A simple three-vortex calculation yielded a period near 15 months, reasonably close to the roughly 12-month signal in the south-polar observations. A separate 2023 analysis applied beta drift to the collective centre of the cyclone group and explained its mean westward motion. Together, the studies describe a system that is simultaneously constrained, oscillating and slowly rotating around the pole. The April 2025 NASA briefing did not create all of this physics at once. It brought the longer Juno tracking record and this series of peer-reviewed models into a clear public picture, applying the spring-like language to the northern polar system. That chronology is more accurate than treating the briefing as a single new paper. Saturn’s hexagon is a different kind of geometry Saturn supplies the obvious visual comparison because a hexagon surrounds its north pole. The resemblance is superficial. Saturn’s six-sided feature is a wavy jet stream encircling one central polar cyclone. Its corners are bends in a continuous current, not six separate cyclone centres. Jupiter’s northern octagon is positional. Eight distinct vortices occupy the vertices around a ninth. At Jupiter’s south pole, five large companions historically formed a pentagon around the centre, and Juno later observed a smaller sixth cyclone joining the system. The 2021 model correctly separated the planets under their observed conditions: Jupiter could support rings of circumpolar cyclones, while Saturn could not. Differences in planet size, rotation, storm dimensions and vorticity profiles alter where force balances are possible. That does not make either geometry permanent. It means the present Jovian arrangement occupies a dynamically permitted regime. Changes in storm strength or size could move the equilibrium, allow a new member into the ring or destabilise an existing one. The model explains persistence better than origin A force balance can explain why established cyclones remain separated without explaining how the first nine formed. Models of moist convection and deep rotating flows can generate polar vortices, but the route from small turbulent storms to Jupiter’s particular north-polar octagon remains an active problem. The storms’ depth is another uncertainty. Cloud-top motion gives a two-dimensional view of a three-dimensional atmosphere. A shallow vortex and a deep column can look similar from above while responding differently to stratification, internal heat and magnetic drag. Juno’s evolving orbit has increasingly carried its microwave radiometer over northern high latitudes. A 2025 modelling study used the observed westward drift to constrain possible vertical structures and supplied predictions for interpreting microwave measurements. It is a model-data comparison, not a direct picture of each cyclone’s base. Local measurements can also mislead if treated as global. SpaceDaily’s earlier account of the Galileo probe’s unusually dry entry site showed how one exquisitely direct atmospheric profile sampled an exceptional hot spot. Juno’s repeated polar maps reduce that problem by following an entire formation through time. A geometric pattern maintained by continual correction The deepest insight is almost the opposite of what the image suggests. Jupiter’s northern cyclone pattern does not survive because nine storms stay put. It survives because motion produces responses that keep bringing the system back towards an organised range of positions. Beta drift presses the cyclones poleward and carries the group west. The central cyclone and the ring members resist crowding through the vorticity fields they impose on one another. Small imbalances become oscillations. Spiral arms can collide while the main cores remain apart. The spring system is therefore an analogy for a measured dynamical balance, not a decorative metaphor. It accounts for the bouncing and contributes to the polygon’s persistence. It does not yet provide a complete history of how the storms formed, how deep all of them extend or how long the arrangement will survive. Juno turned a hidden pole into a sequence of observations long enough to expose that difference. What first looked like a strange geometric portrait is now a moving atmospheric system: nine storms, each thousands of kilometres wide, continually disturbing its neighbours and helping preserve the order they appear to threaten.