The two largest planets in our Solar System, Jupiter and Saturn, share many similarities. They are both massive, primarily made of hydrogen and helium, and have swirling storms and bands of wind. Yet, they also feature fascinating differences, especially in the giant storms that swirl at their poles.
Saturn boasts one enormous storm at each pole, while Jupiter’s poles are home to a large storm surrounded by several smaller ones. This has left scientists scratching their heads about why their polar storms are so distinct.
Recently, two planetary scientists think they’ve unraveled this mystery. Their research dives into how storms form and connect to the planets’ interiors. They suggest that Saturn’s atmosphere allows for free growth of storms, while Jupiter’s atmosphere sets limits on their size.
This theory hinges on how storms are linked to deeper layers of the atmosphere. “The properties of the interior can influence the surface fluid patterns we observe,” says Wanying Kang, a planetary scientist at MIT. Saturn probably has a “harder bottom” than Jupiter, affecting how storms behave.
The weather on both planets is well-known. Each has a turbulent, gaseous atmosphere filled with thick clouds and powerful storms, creating mesmerizing patterns. NASA’s Juno spacecraft has offered a closer look at Jupiter, while Cassini did the same for Saturn, revealing their unique polar storm configurations.
Jiaru Shi, another atmospheric scientist at MIT, points out, “Jupiter and Saturn are nearly identical in size and composition, yet their storms are profoundly different.” To dig deeper, Kang and Shi developed a model to study the surface dynamics of these planets.
In a rotating system like those of gas giants, fluid motion tends to be uniform along the rotation axis. By simplifying the complex three-dimensional dynamics into a two-dimensional model, the pair was able to simulate storm behavior more efficiently.
Storms on gas giants start small, growing from smaller disturbances, influenced by atmospheric depth, heat forces, and friction levels. They discovered that how quickly these limits are reached drastically affects the storm patterns visible in the atmosphere.
Jupiter’s atmosphere allows multiple storms to form, but turbulence stops them from merging into a single vortex. Instead, they create a geometric pattern of storms. “Jupiter’s weaker layering and stronger internal forces keep these storms separate at the surface,” Kang says.
Saturn, on the other hand, has a deeper atmosphere, where weaker forces or greater energy loss through friction might remove barriers to storm merging, resulting in a single massive storm.
This research implies that the patterns of polar storms could reveal clues about the conditions under which they formed. “What we see at the surface may tell us about the interior structure of each planet,” Shi explains. Understanding whether Saturn’s interior is more metal-enriched and contains more condensable material compared to Jupiter can deepen our grasp of these gas giants.
Their findings were published in the Proceedings of the National Academy of Sciences, shedding light on long-standing questions about our neighboring giants. This exciting research underscores how much we still have to uncover about the planets in our Solar System and their intricate weather systems.
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