New Juno findings amaze scientists studying Jupiter

A dramatic infrared view of Jupiter’s north pole, showing a central storm surrounded by eight closely-packed cyclones. Similar, even larger, storms are seen at the south pole. Image: NASA/JPL-Caltech/SwRI/ASI/INAF/JIRAM

New findings from NASA’s Juno spacecraft show Jupiter’s weather systems extend much deeper than previously believed and that the huge planet rotates nearly as a rigid body below the racing jet streams, storms and cyclones.

“This is really an amazing result, and future measurements by Juno will help us understand how the transition works between the weather layer and the rigid body below,” Tristan Guillot, a Juno co-investigator from the Université Côte d’Azur, Nice, France, said in a NASA release. Guillot is the lead author of a paper on Jupiter’s deep interior published in the March 8 issue of the journal Nature.

“Juno’s discovery has implications for other worlds in our solar system and beyond,” he said. “Our results imply that the outer differentially-rotating region should be at least three times deeper in Saturn and shallower in massive giant planets and brown dwarf stars.”

How deep Jupiter’s familiar cloud belts and zones extend has been a mystery for decades, but precise measurements of the planet’s gravity field, the subject of another paper in Nature, show the weather layer, from its top to a depth of some 3,000 kilometres (1,900 miles), contains about three Earth masses of material, or about 1 percent of Jupiter’s total mass.

“By contrast, Earth’s atmosphere is less than one millionth of the total mass of Earth,” said Yohai Kaspi, Juno co-investigator from the Weizmann Institute of Science, Rehovot, Israel, and lead author of another paper on Jupiter’s deep weather layer. “The fact that Jupiter has such a massive region rotating in separate east-west bands is definitely a surprise.”

New infrared imagery of Jupiter’s polar regions reveals eight huge, closely grouped cyclones up to 4,600 kilometres (2,900 miles) across circling a central storm over the north pole with winds whirling about at more than 350 kph (220 mph). Jupiter’s south pole also features a central cyclone surrounded by five even larger storms. They appear to be long-lasting features despite being so close to each other they appear to nearly merge at the boundaries.

“Each one of the northern cyclones is almost as wide as the distance between Naples, Italy and New York City, and the southern ones are even larger than that,” said Alberto Adriani, Juno co-investigator from the Institute for Space Astrophysics and Planetology in Rome and lead author of a fourth paper in Nature describing the features. “There is nothing else like it that we know of in the solar system.

“The question is, why do they not merge? We know with Cassini data that Saturn has a single cyclonic vortex at each pole. We are beginning to realise that not all gas giants are created equal.”