Huge cyclones and asymmetries in the atmosphere of Jupiter

Cyclones at Jupiter's north pole (Image NASA/JPL-Caltech/SwRI/ASI/INAF/JIRAM)
Cyclones at Jupiter’s north pole (Image NASA/JPL-Caltech/SwRI/ASI/INAF/JIRAM)

Four articles published in the journal “Nature” describe as many researches on the planet Jupiter. Different teams of researchers focused on different phenomena using data collected by NASA’s Juno space probe. The researches concerns groups of huge cyclones present in Jupiter’s polar regions, wind flows that extend up to thousands of kilometers of depth, the stripes of the atmosphere that rotate at different speeds and the asymmetries in the planet’s gravitational field.

The Juno space probe entered the planet Jupiter’s orbit on July 4, 2016 and after starting its scientific mission it sent photos and other data that are allowing to better understand this gas giant but are also bringing a number of surprises. Among the studies there are those concerning the atmosphere, mostly divided into strips except in the polar areas, where huge cyclones were found.

The stripes in Jupiter’s atmosphere were discovered by Galileo and yet until today our knowledge of the phenomena behind them was superficial. The gravitational measurements carried out by the Juno space probe allowed to understand how deep they extend and their structure under the visible clouds.

Jupiter’s weather layer reaches the depth of about 3,000 kilometers (1,900 miles) and contains about 1% of the planet’s mass. That’s a percentage much higher than on the Earth, whose atmosphere is less than one millionth of its total mass.

Other data suggest that underneath that layer the planet rotates almost like a rigid body even though it’s still a gas ball. These results allow a better understanding of other planets as well: for example the outer regions with different rotation speeds should go at least three times deeper on Saturn. On other very massive giant planets and brown dwarfs, on the boundary between planet and star, those layers should reach lower depths.

The detections show a connection between the gravitational “signature” of the wind flows and that of Jupiter’s core. The greater the depth those flows reach, the more mass they contain and this reinforces the signal expressed in the gravitational field. In essence, different researches were presented but at the same time they’re at least partially connected.

The most spectacular phenomena, however, are the huge cyclones discovered in Jupiter’s polar regions. They can be thousands of kilometers wide and the winds inside them have speeds up to 350 kph (220 mph). Two cyclones correspond to each of the poles and in both cases they’re surrounded by other cyclones. They’re very close to each other and yet remain distinct, a mystery still to be solved.

From this point of view, Jupiter seems very different from Saturn, which has a single cyclone at each pole. This is also a mystery and the researchers hope to find the solution in the data that get collected by the Juno space probe every time it passes over those regions. The solution could provide new information on gas giants in general to understand why each of these planets is different.

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