Webb Uncovers Unexpected Phenomena Above Jupiter’s Great Red Spot

Jupiter’s Atmosphere Around the Great Red Spot (Webb NIRCam and NIRSpec)

New observations of the Great Red Spot on Jupiter have revealed that the planet’s atmosphere above and around the infamous storm is surprisingly interesting and active. This graphic shows the region observed by Webb – first its location on a NIRCam image of the whole planet (left), and 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)

Using the James Webb Space Telescope, scientists observed the region above Jupiter’s iconic Great Red Spot to discover a range of previously unseen features. The region, previously believed to be unremarkable in nature, hosts a variety of intricate structures and activity.

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

Unveiling Jupiter’s Atmosphere

Jupiter is one of the brightest objects in the night sky, and it is easily seen on a clear night. Aside from the bright northern and southern lights at the planet’s polar regions, the glow from Jupiter’s upper atmosphere is weak and is therefore challenging for ground-based telescopes to discern details in this region. However, Webb’s infrared sensitivity allows scientists to study Jupiter’s upper atmosphere above the infamous Great Red Spot with unprecedented detail.

The upper atmosphere of Jupiter is the interface between the planet’s magnetic field and the underlying atmosphere. Here, the bright and vibrant displays of northern and southern lights can be seen, which are fuelled by the volcanic material ejected from Jupiter’s moon Io. However, closer to the equator, the structure of the planet’s upper atmosphere is influenced by incoming sunlight. Because Jupiter receives only 4% of the sunlight that is received on Earth, astronomers predicted this region to be homogeneous in nature.

The Great Red Spot of Jupiter was observed by Webb’s Near-InfraRed Spectrograph (NIRSpec) in July 2022, using the instrument’s Integral Field Unit capabilities. The team’s Early Release Science observations sought to investigate if this region was in fact dull, and the region above the iconic Great Red Spot was targeted for Webb’s observations. The team was surprised to discover that the upper atmosphere hosts 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 over 300 km above the clouds of the storm, where light from the Sun ionizes the hydrogen and stimulates this infrared emission. In this image, redder colors display the 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 distant 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 especially strong. Contrary to the researchers’ expectations that this area would therefore look homogeneous in nature, it hosts a variety of intricate structures, including dark arcs and bright spots, across the entire field of view.
Credit: ESA/Webb, NASA & CSA, H. Melin, M. Zamani (ESA/Webb)

Surprising Findings Above the Great Red Spot

“We thought this region, perhaps naively, would be really boring,” shared team leader Henrik Melin of the University of Leicester in the United Kingdom. “It is in fact just as interesting as the northern lights, if not more so. Jupiter never ceases to surprise.”

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

“One way in which you can change this structure is by gravity waves – similar to waves crashing on a beach, creating ripples in the sand,” explained Henrik. “These waves are generated deep in the turbulent lower atmosphere, all around the Great Red Spot, and they can travel up in altitude, changing the structure and emissions of the upper atmosphere.”

Future Observations and Implications

The team explains that these atmospheric waves can be observed on Earth on occasion, however, they are much weaker than those observed on Jupiter by Webb. They also hope to conduct 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 budget of this region and how the features change over time.

These findings may 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 Europa – with a suite of remote sensing, geophysical, and in situ instruments. The mission will characterize these moons as both planetary objects and possible habitats, explore Jupiter’s complex environment in-depth, and study the wider Jupiter system as an archetype for gas giants across the Universe.

Reflections on the Research’s Impact

These observations were taken as part of the Early Release Science program #1373: ERS Observations of the Jovian System as a Demonstration of JWST’s Capabilities for Solar System Science (Co-PIs: I. de Pater, T. Fouchet).

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

These results have been published in Nature Astronomy.

Reference: “Ionospheric irregularities at Jupiter observed by JWST” by Henrik Melin, J. O’Donoghue, L. Moore, T. S. Stallard, L. N. Fletcher, M. T. Roman, J. Harkett, O. R. T. King, E. M. Thomas, R. Wang, P. I. Tiranti, K. L. Knowles, I. de Pater, T. Fouchet, P. H. Fry, M. H. Wong, B. J. Holler, R. Hueso, M. K. James, G. S. Orton, A. Mura, A. Sánchez-Lavega, E. Lellouch, K. de Kleer and M. R. Showalter, 21 June 2024, Nature Astronomy.
DOI: 10.1038/s41550-024-02305-9

Webb is the largest, most powerful telescope ever launched into space. Under an international collaboration agreement, ESA provided the telescope’s launch service, using the Ariane 5 launch vehicle. Working with partners, ESA was responsible for the development and qualification of Ariane 5 adaptations 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 MIRI, which was designed and built by a consortium of nationally funded European Institutes (The MIRI European Consortium) in partnership 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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