Decades-old mystery about Jupiter’s winds solved

The violent winds in Jupiter’s atmosphere have long fascinated astronomers and planetary researchers. Images from several telescopes and space probes show numerous turbulences in the clouds and strong east-west jet streams that spread across the planet in characteristic red and white bands. Now, an international team led by lead author Yohai Kaspi of Israel’s Weizmann Institute of Science wants to resolve a decades-old dispute. Using data from the Juno mission, scientists modeled that atmospheric winds spin like hollow cylinders placed one inside another at different speeds around the planet’s axis of rotation. Previous assumptions assumed that they extended radially in all directions. They present their results in the specialized magazine “Nature Astronomy”.

NASA’s Juno spacecraft has been closely watching the violent activity in Jupiter’s atmosphere since 2016. The satellite has already orbited Jupiter a total of 55 times and has examined the atmosphere and clouds on the surface with the numerous scientific instruments carried on board. Astronomers will also track the spacecraft’s radio signal using NASA’s Deep Space Network, a global network of antennas, as Juno passes by Jupiter at nearly 125,000 miles per hour. This corresponds to approximately 85 times the speed of a jet aircraft. They use it to detect small changes in speed, with an accuracy of up to 0.01 millimeters per second. These variations are caused by fluctuations in the planet’s gravitational field and can be used to learn more about the atmosphere.

“We processed the Juno data using a method that was originally developed for data sets from rocky planets like Earth,” explains Ryan Park, a scientist at the Jet Propulsion Laboratory in Pasadena and co-author, according to a press release. This is the first time that such a technique has been applied to a gaseous planet. The authors were able to quadruple the resolution compared to previous models created using data from NASA’s two spacecraft, Voyager and Galileo.

The new gravitational field measurement data basically coincides with a 20-year-old theoretical prediction, according to which strong east-west currents extend inland from areas of white and red clouds. They also support the idea that atmospheric winds are aligned cylindrically along Jupiter’s axis of rotation, like the layers of a tree cake. The research team is confident that this means that the evaluation of the new measurement data has ended a debate about the nature of Jupiter’s atmosphere, a debate that began in the 1970s.

“The 40 gravity coefficients measured by Juno agree with the model’s predictions, which arise when the winds penetrate cylindrically inward,” says Yohai Kaspi. “When we discovered that the 40 values ​​corresponded exactly to our calculations, it was like winning the lottery.” The new gravity model not only improves the current understanding of the internal structure and origin of Jupiter, but can also be used to obtain more information on other planets. Researchers are confident that they can obtain planetary atmospheres.