The mystery of how giant cyclones come together in geometric patterns around Jupiter’s poles may now be solved, but new questions have emerged about how these clusters formed in the first place, according to a new study.
After NASA’s Juno spacecraft entered orbit around Jupiter in 2016, the spacecraft discovered giant cyclones arranged in geometric patterns around the world’s poles. At the north pole of the planet, there are eight eddies surrounding a central vortex and at the south pole there are six.
“We were surprised that Jupiter’s poles aren’t like those of other planets,” study lead author Cheng Li, a planetary scientist at the University of California, Berkeley, told Space.com. “We have never seen anything like these groups of cyclones organized in regular patterns.”
Each gigantic storm ranges from 2,485 to 4,350 miles (4,000 to 7,000 kilometers) and surround their respective poles at distances of 5,400 miles (8,700 km). These cyclones and patterns have endured for at least four years since Juno arrived on Jupiter.
It was a mystery to scientists how these clusters remained stable. On Earth, cyclones move towards the poles but dissipate on land and cold water, Li said. In contrast, Jupiter has neither land nor oceans, raising the question of why the cyclones didn’t simply shift to the poles and come together. (For example, Saturn has a single cyclone on each of its poles.)
“All previous theories predicted that the polar regions of giant planets should be dominated by large cyclones on their poles, like what is observed in Saturn, or remain chaotic,” said Li, who is taking a new position at the University. of Michigan in Ann Arbor. “What we see in Jupiter means those previous theories are wrong, and we need something new.”
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To shed light on Jupiter’s cyclones, Li and her colleagues developed computer models based on what Juno revealed about the size and speed of storms. They focused on what factors could keep these geometric patterns stable over time without merging.
The researchers found that the stability of these patterns depends in part on how deep the cyclones reach Jupiter’s atmosphere, but mainly on the anticyclonic rings around each cyclone, i.e. a wind ring that rotates in the opposite direction that each one rotates. cyclone. little shielding from anticyclone rings led to cyclone melting; excessive shielding could draw cyclones away from each other.
There are many unsolved mysteries regarding these cyclone clusters. For example, it remains unknown why Jupiter’s vortices occupy this happy medium between too much and too little shielding. “Right now we have no idea what makes them sit in this sweet spot,” Li said.
Scientists are now studying how these cyclones might have formed in the first place. One possibility is that they formed near the poles, where they currently are. The other, “which we think is more likely, is that they formed elsewhere and then migrated to the poles,” Li said.
Once researchers have generated computer models based on Juno’s data to see which of these formation scenarios is more likely, they can then begin to see how these cyclones organize themselves into these stable patterns.
This may prove to be a more difficult question to answer, “because this involves detailed 3D modeling of how these vortices are generated and there are many parameters about these vortices that we don’t know, such as their vertical structure,” Li said. “But we can try different scenarios to see what vertical structures could generate the wind speed profiles that we have observed with these cyclones and move on from there.”
The scientists detailed their findings online Sept. 7 in the journal Proceedings of the National Academy of Sciences.
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