Decades-old mystery about Jupiter’s winds solved

The violent winds in Jupiter’s atmosphere have long fascinated astronomers and planetary researchers. Images from multiple telescopes and space probes show numerous cloud turbulences and strong east-west jet streams that stretch across the planet in characteristic red and white stripes. Now, an international team led by lead author Yohai Kaspi of the Israeli Weizmann Institute of Science wants to resolve a decades-old dispute. Using data from the Juno mission, scientists modeled that atmospheric winds rotate like hollow cylinders placed one inside the other 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 observing violent activity in Jupiter’s atmosphere since 2016. The satellite has orbited Jupiter a total of 55 times and examined the atmosphere and clouds on the surface using the numerous scientific instruments 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 Jupiter at nearly 200,000 kilometers per hour. This corresponds to about 85 times the speed of a jet plane. 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 discover more about the atmosphere.

“We processed the Juno data using a method that was originally developed for datasets 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 such a technique has been applied to a gaseous planet. The authors were able to increase the resolution four times compared to previous models that were created using data from NASA’s two spacecraft Voyager and Galileo.

The new gravitational field measurement data largely agreed with a 20-year-old theoretical prediction that strong east-west currents extend inward from the white and red cloud zones. They also support the idea that atmospheric winds are aligned cylindrically along Jupiter’s rotation axis, like the layers of a tree cake. The research team is certain that this means that the evaluation of the new measurement data has put an end to a debate about the nature of Jupiter’s atmosphere – a debate that began in the 1970s.

“All 40 gravity coefficients measured by Juno agree with the model’s predictions, which arise if winds penetrate inward in a cylindrical shape,” says Yohai Kaspi. “When we discovered that all 40 values ​​matched our calculations exactly, it was like winning the lottery.” The new gravitational model not only improves current understanding of Jupiter’s internal structure and origin, but can also be used to gain further insights into other researchers are certain they can obtain planetary atmospheres.