The newly-discovered intense (140 m/s) jet is confined to ±3° of Jupiter’s equator, is approximately 4,800 km wide, and is located in the gas giant’s lower stratosphere, according to a paper published in the journal Nature Astronomy.
This Webb image of Jupiter shows stunning details of the majestic planet in infrared light. In this image, brightness indicates high altitude. The numerous bright white ‘spots’ and ‘streaks’ are likely very high-altitude cloud tops of condensed convective storms. Aurorae, appearing in red in this image, extend to higher altitudes above both the northern and southern poles of the planet. By contrast, dark ribbons north of the equatorial region have little cloud cover. Image 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.
“This is something that totally surprised us,” said Dr. Ricardo Hueso, an astronomer at the University of the Basque Country.
“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.”
In the study, Dr. Hueso and colleagues analyzed data gathered by Webb’s Near-Infrared Camera (NIRCam) instrument in July 2022.
“Even though various ground-based telescopes, spacecraft like NASA’s Juno and Cassini, and the NASA/ESA 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,” said Professor Imke de Pater, an astronomer at the University of California, Berkeley.
“While Jupiter is different from Earth in many ways — Jupiter is a gas giant, Earth is a rocky, temperate world — both planets have layered atmospheres.”
“Infrared, visible, radio, and ultraviolet-light wavelengths observed by these other missions detect the lower, deeper layers of the planet’s atmosphere — where gigantic storms and ammonia ice clouds reside.”
“On the other hand, Webb’s look farther into the near-infrared than before is sensitive to the higher-altitude layers of the atmosphere, around 25-50 km above Jupiter’s cloud tops.”
“In near-infrared imaging, high-altitude hazes typically appear blurry, with enhanced brightness over the equatorial region. With Webb, finer details are resolved within the bright, hazy band.”
Hueso et al. discovered a high-speed jet stream sitting over Jupiter’s equator, above the main cloud decks. At a wavelength of 2.12 microns, which observes between altitudes of about 20-35 km above Jupiter’s cloud tops, the astronomers 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. Image 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 newly-discovered jet stream travels at about 515 km per hour, twice the sustained winds of a Category 5 hurricane here on Earth.
It is located around 40 km above the clouds, in Jupiter’s lower stratosphere.
By comparing the winds observed by Webb at high altitudes, to the winds observed at deeper layers from Hubble, the astronomers could measure how fast the winds change with altitude and generate wind shears.
While Webb’s exquisite resolution and wavelength coverage allowed for the detection of small cloud features used to track the jet, the complementary observations from Hubble taken one day after the Webb observations were also crucial to determine the base state of Jupiter’s equatorial atmosphere and observe the development of convective storms in Jupiter’s equator not connected to the jet.
“We knew the different wavelengths of Webb and Hubble would reveal the three-dimensional structure of storm clouds, but we were also able to use the timing of the data to see how rapidly storms develop,” said Dr. Michael Wong, an astronomer at the University of California, Berkeley.
The researchers are looking forward to additional observations of Jupiter with Webb 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,” said Dr. Leigh Fletcher, an astronomer at the University of Leicester.
“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.”
“It’s amazing to me that, after years of tracking Jupiter’s clouds and winds from numerous observatories, we still have more to learn about Jupiter, and features like this jet can remain hidden from view until these new NIRCam images were taken in 2022.”
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R. Hueso et al. An intense narrow equatorial jet in Jupiter’s lower stratosphere observed by JWST. Nat Astron, published online October 19, 2023; doi: 10.1038/s41550-023-02099-2
