Webb Discovers Unexpected Phenomena Above Jupiter’s Great Red Spot

Jupiter's atmosphere around the Great Red Spot (Webb NIRCam and NIRSpec)

New observations of Jupiter’s Great Red Spot have revealed that the planet’s atmosphere above and around the infamous storm is surprisingly interesting and active. This image shows the region Webb observed – first the location on a NIRCam image of the entire planet (left), and then the region itself (right), imaged by Webb’s Near-InfraRed Spectrograph (NIRSpec). Credit: ESA/Webb, NASA & CSA, Jupiter ERS Team, J. Schmidt, H. Melin, M. Zamani (ESA/Webb)

The habits James Webb Space Telescopescientists observed the region above Jupiter‘s iconic Great Red Spot to discover a series of previously unseen features. The region, previously thought to be unremarkable in nature, is home to a variety of intricate structures and activities.

Recent observations by Webb’s NIRSpec have revealed surprising details about Jupiter’s upper atmosphere, particularly above the Great Red Spot, and revealed complex structures affected by gravitational waves. These findings, captured using Webb’s high-resolution capabilities, could support the Jupiter Icy Moons Explorer (Juice) mission, and further our understanding of Jupiter and its moons.

Jupiter’s Atmosphere Revealed

Jupiter is one of the brightest objects in the night sky and is easy to see on a clear night. Aside from the bright northern and southern lights near the planet’s polar regions, Jupiter’s upper atmosphere is dim, making it difficult for ground-based telescopes to resolve details in this region. However, Webb’s infrared sensitivity allows scientists to study Jupiter’s upper atmosphere above the infamous Great Red Spot in unprecedented detail.

Jupiter’s upper atmosphere is the interface between the planet’s magnetic field and the atmosphere below. It is here that bright and vivid displays of the Northern and Southern Lights can be seen, fueled by volcanic material ejected from Jupiter’s moon Io. Closer to the equator, however, the structure of the planet’s upper atmosphere is affected by incoming sunlight. Because Jupiter receives only 4% of the sunlight that Earth receives, astronomers predicted that this region would be homogeneous in nature.

Jupiter’s Great Red Spot was observed in July 2022 by Webb’s Near-InfraRed Spectrograph (NIRSpec), using the instrument’s Integral Field Unit capabilities. The team’s Early Release Science observations sought to investigate whether this region was indeed dim, and the region above the iconic Great Red Spot was the target of Webb’s observations. The team was surprised to find that the upper atmosphere harbors a variety of intricate structures, including dark arcs and bright spots, across the entire field of view.

Jupiter's atmosphere around the Great Red Spot (Webb NIRSpec image)

Webb NIRSpec observations show infrared light emitted by hydrogen molecules in Jupiter’s ionosphere. These molecules lie more than 300 km above the storm’s clouds, where light from the sun ionizes the hydrogen and drives this infrared emission. In this image, redder colors show hydrogen emission from these high altitudes in the planet’s ionosphere. Bluer colors show infrared light from lower altitudes, including cloud tops in the atmosphere and the very prominent Great Red Spot.
Jupiter is far from the Sun and therefore receives a uniform, low level of daylight, meaning that most of the planet’s surface is relatively dim at these infrared wavelengths – especially compared to the emission from molecules near the poles, where Jupiter’s magnetic field is particularly strong. Contrary to researchers’ expectations that this region would therefore appear homogeneous in nature, it hosts a variety of intricate structures, including dark arcs and bright spots, across the field of view.
Source: ESA/Webb, NASA & CSA, H. Melin, M. Zamani (ESA/Webb)

Surprising discoveries above the Great Red Spot

“We thought, perhaps naively, that this region would be very boring,” said team leader Henrik Melin of the University of Leicester in the United Kingdom. “In fact, it’s as interesting as the Northern Lights, if not more so. Jupiter never ceases to amaze.”

Although the light emitted from this region is driven by sunlight, the team suggests there must be another mechanism changing the shape and structure of the upper atmosphere.

“One way you can change this structure is through gravity waves – similar to waves that crash onto a beach and create ripples in the sand,” Henrik explained. “These waves are generated deep in the turbulent lower atmosphere, surrounding the Great Red Spot, and they can travel up in height, changing the structure and emissions of the upper atmosphere.”

Future observations and implications

The team explains that these atmospheric waves can occasionally be seen on Earth, but they are much weaker than those Webb observed on Jupiter. They also hope to perform follow-up Webb observations of these intricate wave patterns in the future to investigate how the patterns move within the planet’s upper atmosphere and to develop our understanding of the energy balance of this region and how its features change over time.

These findings could also support ESA’s Jupiter Icy Moons Explorer, JUICE, which was launched on 14 April 2023. JUICE will make detailed observations of Jupiter and its three large ocean-bearing moons – Ganymede, Callisto and Europe – with a suite of remote sensing, geophysical, and in situ instruments. The mission will characterize these moons as both planetary objects and potential habitats, deeply explore Jupiter’s complex environment, and study the broader Jovian system as an archetype for gas giants in the universe.

Reflections on the impact of the research

These observations were made as part of the Early Release Science program #1373: ERS observations of the Jupiter system demonstrate JWST’s capabilities for solar system science (Co-PIs: I. de Pater, T. Fouchet).

“This ERS proposal was already written in 2017,” shared team member Imke de Pater of the University of California, Berkeley“One of our goals was to investigate why the temperature above the Great Red Spot appeared to be so high, as suggested by recent observations with the NASA Infrared Telescope Facility had revealed. However, our new data showed very different results.”

These results were published in Natural astronomy.

Reference: “Ionospheric Irregularities at Jupiter Observed by JWST” by Henrik Melin, J. O’Donoghue, L. Moore, TS Stallard, LN Fletcher, MT Roman, J. Harkett, ORT King, EM Thomas, R. Wang, PI Tiranti, KL Knowles, I. de Pater, T. Fouchet, PH Fry, MH Wong, BJ Holler, R. Hueso, MK James, GS Orton, A. Mura, A. Sánchez-Lavega, E. Lellouch, K. de Kleer and MR Showalter, June 21, 2024, Nature Astronomy.
DOI file: 10.1038/s41550-024-02305-9

Webb is the largest, most powerful telescope ever launched into space. Under an international cooperation agreement, ESA provided the launch service for the telescope, using the Ariane 5 launch vehicle. Together with partners, ESA was responsible for the development and qualification of Ariane 5 modifications for the Webb mission and for the procurement of the launch service by Arianespace. ESA also provided the workhorse spectrograph NIRSpec and 50% of the mid-infrared instrument MIRwhich was designed and built by a consortium of nationally funded European institutes (the MIRI European Consortium) in collaboration with JPL and the University of Arizona.

Webb is an international partnership between NASA, ESA and the Canadian Space Agency (CSA).

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