Scientists find odd and amazing cyclones at Jupiter’s poles

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  • This composite image, derived from data collected by the Jovian Infrared Auroral Mapper (JIRAM) instrument aboard NASA’s Juno mission to Jupiter, shows the central cyclone at the planet’s north pole and the eight cyclones that encircle it.
    NASA/JPL-Caltech/SwRI/ASI/INAF/JIRAM
  • The image shows the structure of the cyclonic pattern observed over Jupiter’s north pole: a central cyclone surrounded by eight circumpolar cyclones with diameters ranging from 4,000 to 4,600 kilometers.
    NASA/JPL-Caltech/SwRI/ASI/INAF/JIRAM
  • This computer-generated image shows the structure of the cyclonic pattern observed over Jupiter’s south pole.
    NASA/JPL-Caltech/SwRI/ASI/INAF/JIRAM
  • This picture of Jupiter’s south pole is a mosaic of many images acquired by the Jovian InfraRed Auroral Mapper at wavelengths around 5 µm during perijove pass number 4.

Scientists studying data from NASA’s Juno spacecraft have published a trove of papers in Nature this week, making a number of intriguing and surprising findings about the atmosphere of the largest planet in our Solar System. The papers are summarized and linked in this NASA news release.

Some of the most striking discoveries come from visible and infrared observations made by Juno during its first five science passes in its elongated orbit around Jupiter. (The spacecraft entered Jupiter’s orbit on July 4, 2016. It will make its 11th pass on April 1.) In these initial passes, scientists found clusters of strange and long-lasting cyclones orbiting the north and south poles of Jupiter.

At the north pole, eight persistent, polygon-shaped cyclones were observed around a single polar cyclone. In the south, five storms circled a single cyclone. Scientists confirmed the circulation of these storms through time-lapse imagery. The northern storms, measuring 4,000 to 4,600km in diameter, are smaller than the southern hemisphere storms, which are 5,600 to 7,000km in diameter.

Normally, scientists would expect these cyclones to migrate toward the pole due to the Coriolis beta effect, in which vortices in a fluid would naturally drift toward the pole. However, on Jupiter, these vortices have persisted and not drifted substantially or merged during Juno’s initial observations. This has surprised scientists, because the polar cyclones are so densely packed, with the spiral arms of each one coming into contact with its neighbors.

They should be pushing and pulling at one another and merging as a result. “The question is, why do they not merge?” said Alberto Adriani, Juno co-investigator from the Institute for Space Astrophysics and Planetology, Rome, and lead author of the paper. “We know with Cassini data that Saturn has a single cyclonic vortex at each pole. We are beginning to realize that not all gas giants are created equal.”

As the researchers note, “The configuration of the cyclones is without precedent on other planets.” NASA scientists are now trying to model the atmospheric conditions under which such features might form and persist in the Jovian atmosphere. More data from future Juno passes by Jupiter will certainly help.

Listing image by NASA/SWRI/JPL/ASI/INAF/IAPS

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