Why a 3,000-mile-long jet stream on Jupiter surprised NASA scientists

JWST captured a never-before-seen jet stream with winds twice as strong as a Category 5 hurricane.
An image of Jupiter taken with the James Webb Space Telescope’s NIR Cam in July 2022. Researchers recently discovered a narrow jet stream traveling 320 miles per hour sitting over Jupiter’s equator above the main cloud decks. The numerous bright white "spots" and "streaks" are likely very high-altitude cloud tops of condensed convective storms. Auroras, appearing in red in this image, extend to higher altitudes above both the northern and southern poles of the planet.

In July 2022, James Webb Space Telescope’s NIR Cam captured this image of Jupiter in infrared light. Researchers recently discovered a narrow jet stream traveling 320 miles per hour sitting over Jupiter’s equator above the main cloud decks. The numerous bright white "spots" and "streaks" are likely very high-altitude cloud tops of condensed convective storms. Auroras, appearing in red in this image, extend to higher altitudes above both the northern and southern poles of the planet. NASA, ESA, CSA, STScI, Ricardo Hueso (UPV), Imke de Pater (UC Berkeley), Thierry Fouchet (Observatory of Paris), Leigh Fletcher (University of Leicester), Michael H. Wong (UC Berkeley), Joseph DePasquale (STScI)

Jupiter and its dynamic atmosphere are ready for another closeup in a new image taken with the James Webb Space Telescope (JWST). Using the telescope’s data, scientists have discovered a new and never-before-captured high-speed jet stream. The jet stream sits over Jupiter’s equator above the main cloud decks, barrels at speeds twice as high as a Category 5 hurricane, and spans more than 3,000 miles. The findings were described in a study published October 19 in the journal Nature Astronomy.

[Related: This hot Jupiter exoplanet unexpectedly hangs out with a super-Earth.]

Jupiter is the largest planet in our solar system and its atmosphere has some very visible features, including the infamous Great Red Spot, which is large enough to swallow the Earth. The planet is ever-changing and there are still mysteries in this gas giant that scientists are trying to unravel. According to NASA, the new discovery of the jet stream is helping them decipher how the layers of Jupiter’s famously turbulent atmosphere interact with each other. Now, JWST is helping scientists look further into the planet and see some of the lower and deeper layers of Jupiter’s atmosphere where gigantic storms and ammonia ice clouds reside. 

“This is something that totally surprised us,” study co-author Ricardo Hueso said in a statement.  “What we have always seen as blurred hazes in Jupiter’s atmosphere now appear as crisp features that we can track along with the planet’s fast rotation.” Hueso is an astrophysicist at the University of the Basque Country in Bilbao, Spain.

The research team analyzed data from JWST’s Near-Infrared Camera (NIRCam) that was obtained in July 2022. The Early Release Science program was designed to take images of Jupiter 10 hours apart (one Jupiter day) in four different filters. Each filter detected different types of changes in the small features located at various altitudes of Jupiter’s atmosphere.

At a wavelength of 2.12 microns, which observes between altitudes of about 12-21 miles above Jupiter’s cloud tops, researchers spotted several wind shears, or areas where wind speeds change with height or with distance, which enabled them to track the jet. This image highlights several of the features around Jupiter’s equatorial zone that, between one rotation of the planet (10 hours), are very clearly disturbed by the motion of the jet stream. CREDIT: NASA, ESA, CSA, STScI, Ricardo Hueso (UPV), Imke de Pater (UC Berkeley), Thierry Fouchet (Observatory of Paris), Leigh Fletcher (University of Leicester), Michael H. Wong (UC Berkeley), Joseph DePasquale (STScI)

The resulting image shows Jupiter’s atmosphere in infrared light. The jet stream is located over the equator, or center, of the planet. There are multiple bright white spots and streaks that are likely very high-altitude cloud tops of condensed convective storms. Jupiter’s northern and southern poles are dotted by auroras that appear red and extend to the higher altitudes of the planet. 

“Even though various ground-based telescopes, spacecraft like NASA’s Juno and Cassini, and NASA’s Hubble Space Telescope have observed the Jovian system’s changing weather patterns, Webb has already provided new findings on Jupiter’s rings, satellites, and its atmosphere,” study co-author and University of California, Berkeley astronomer Imke de Pater said in a statement.  

The newly discovered jet stream travels at roughly 320 miles per hour and is located close to 25 miles above the clouds, in Jupiter’s lower stratosphere. The team compared the winds observed by JWST at higher altitudes with the winds observed at deeper layers by the Hubble Space Telescope. This enabled them to measure how fast the winds change with altitude and generate wind shears.

[Related: Jupiter formed dinky little rings, and there’s a convincing explanation why.]

The team hopes to use additional observations of Jupiter to determine if the jet’s speed and altitude change over time. 

“Jupiter has a complicated but repeatable pattern of winds and temperatures in its equatorial stratosphere, high above the winds in the clouds and hazes measured at these wavelengths,” Leigh Fletcher, a study co-author and planetary scientists at the University of Leicester in the United Kingdom, said in a statement. “If the strength of this new jet is connected to this oscillating stratospheric pattern, we might expect the jet to vary considerably over the next 2 to 4 years–it’ll be really exciting to test this theory in the years to come.”