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 
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 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
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