For years, scientists have been trying to explain why Jupiter and Saturn, two planets that are so similar in terms of their size and composition, could have such vastly different polar weather. Saturn’s north pole features one gigantic hexagonal storm, while Jupiter’s has a big central cyclone with eight smaller ones around it. Now, researchers think this difference may come down to each planet’s interior: differences in how “hard” or “soft” the deep gas is could determine whether one storm dominates or multiple form.
Polar vortices and surface weather
According to observations from Cassini, Saturn’s north pole is capped by a single massive storm in a distinctive hexagon shape. Juno’s images of Jupiter revealed a very different pattern: one large cyclone at the pole surrounded by eight smaller vortices. Each of Jupiter’s polar storms spans about 3,000 miles across, whereas Saturn’s lone vortex stretches about 18,000 miles wide. This stark contrast has puzzled scientists, since both planets are similar in size and composition.
Clues to planetary interiors
MIT researchers simulated the fluid dynamics of polar storms on these planets. They concluded that the type of gas present at the bottom of a whirlpool is crucial, with a “soft” (less dense) bottom hindering the growth of a storm, leading to multiple whirlpools originating (like Jupiter), while a “harder” (denser) bottom means a prominent solo storm (like Saturn). According to an MIT researcher, Wanying Kang, “one possible scenario could be that Saturn has a harder bottom than Jupiter,” which would suggest an internally lighter Jupiter than Saturn, perhaps due to a greater abundance of heavier elements.
