To support the Juno mission and provide necessary spatial and spectral context to measurements made by the spacecraft, the science team has established and coordinated an international network of observational astronomers and Earth-based observatories. This network of supporting observations of the Jovian system continues to expand. The measurements cover a broad spectral range with over 60 groups contributing to the campaign. The support provided by these observations constitutes several specific enhancements to Juno’s own data. (1) They provide knowledge about the evolution of features detected by the spacecraft at a single point in time. (2) Contextual information is gathered about the larger spatial environment surrounding the often very limited regions covered by Juno’s own instruments. (3) The spectral range covered by Juno’s suite of instruments is expanded, now including observations that cover X-ray through radio wavelengths. Observations at intermediate wavelengths, such as the mid-infrared, can detect thermal signatures that can measure temperatures in the upper troposphere through stratosphere unambiguously. (4) Supporting measurements also assess the extent to which distant phenomena taking place within the Jovian system may influence atmospheric or auroral properties detected by Juno’s instruments, such as the mass loading from Io by tracking its observed volcanic activity and the opacity of its torus. Observations of Jupiter’s neutral atmosphere included images and spectra of reflected sunlight from the near-ultraviolet through the near-infrared and thermal emission from 5 µm through the radio region.  The ultimate goal of these Earth-based measurements is to relate properties of the deep atmosphere (that are the focus of Juno’s mission) to the state of the “weather layer” at much lower pressures  Of special consideration during Juno’s extended mission are observations of thermal emission that cover narrow regions where temperature profiles are created from the phase change of the high-beam antenna’s radio signal as it is being occulted by Jupiter’s atmosphere. The spectral region and timeline of all of these observations are summarized in the web site: https://www.missionjuno.swri.edu/planned-observations. Besides a global network of professional astronomers, the Juno mission also benefited significantly from a network of dedicated amateur astronomers who provided a quasi-continuous picture of the evolution of features observed by Juno’s instruments. Examples of support will be shown from the primary and extended mission.

How to cite: Orton, G., Momary, T., Dahl, E., Brueshaber, S., Rogers, J., Bolton, S., and Levin, S.: The Juno-Supporting Earth-Based Observing Campaign, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7854, https://doi.org/10.5194/egusphere-egu25-7854, 2025.

The moon Io, the most active volcanic body in the Solar System,  is the “energy convertor” of the Jupiter system: indeed, Io’s interior is  continuously heated by tidal interactions with Jupiter and the other Galilean moons, while its volcanic activity is the main source of its neutral and plasma torus and generates the Jovian magnetodisk via complex processes likely related to a centrifugal instability.

A number of spacecraft have flown by Jupiter or have been placed into orbit around the planet. Some of them crossed the Io Plasma Torus (IPT), which is the main source of charged particles for the magnetosphere of Jupiter, revealing the complex spatial structure of the IPT. As an important complement, observations of the IPT from the Earth’s surface that are presented at this session, together with observations from Earth orbit (JAXA’s Hisaki) have revealed not only that the spatial structure of the IPT is complex, but also that it displays a large temporal variability over a broad spectrum of timescales, from hours to decades. Achieving a deeper understanding of the sources that drive the complex spatial structure and temporal variability of the IPT remains a very challenging open scientific question. In return, addressing this challenge will provide us with a key piece in the assembly of the puzzle of the Jupiter System.

While a new international flotilla of spacecraft is heading to Jupiter, time is ripe to unite all Io and IPT observers, space-based and Earth-based, to contribute to an around-the-world program of continuous observations. By the addition of observations at different longitudes from America, Hawaii, Japan, China, Europe and Africa, it will be possible to retrieve the complexity of the temporal variability of the IPT, while providing unique support to current Juno observations and upcoming observations by JUICE, Europa Clipper, TianWen-4 and hopefully LAPYUTA.

In this talk, we will review the rich diversity of IPT observations from space and from Earth, propose a modelling tool to assimilate all data into a single model of the Io torus, and propose that the Io and Jupiter science community work together to establish this joint endeavor as a major international scientific program.

How to cite: Blanc, M., Vinci, G., Andre, N., Hue, V., Mousis, O., Devinat, M., Rabia, J., Nenon, Q., and Mura, A.: Earth-based monitoring of Io torus Proposition for a Community Project, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19678, https://doi.org/10.5194/egusphere-egu25-19678, 2025.

Jupiter and Saturn played a major role in the formation and evolution of the Solar System. The internal structure of the gas giants was shaped during their birth process and still contains traces of this formation. A detailed description of the internal structure would be key for understanding physical properties, Equations of State, high-pressure physics, effects of rotation, heat transfer, interaction between interiors and atmospheres, and finally would be a necessary step for the study of extra solar planets.

The measurement of gravitational moments by space missions can give a view of the internal structure. However, it is only sensitive to the external layers. Despite recent progress provided by the spacecrafts Juno and Cassini, our knowledge of the repartition of pressure, temperature and composition inside giant planets remains sparse and would not permit a unique model solution. The situation for Uranus and Neptune is even worse as these planets have not received any visit since Voyager. Among the different methods able to reveal the internal structure of planets, seismology is certainly the most powerful. A complete set of acoustic oscillations could give a profile of the sound speed and the rotation rate along the radius and latitudes. However, it requires long continuous observations, difficult to achieve from the ground.

So far, seismic measurements of Saturn have been obtained thanks to structure in the rings observed by Cassini and attributed to resonances with surface waves (f modes) of the planet. Ring seismology is very powerful as it allows recording of oscillations for many years, giving sensitivity and precision on the frequencies not achievable with other means. The analysis of these frequencies has shown the existence of stable layers inside Saturn. This fantastic result could not be extended further because of the small number of modes able to resonate with the rings. Gravity measurements from Cassini and Juno also proved the existence of acoustic modes on Jupiter and Saturn with detectable amplitudes but could not measure individual frequencies.

Many efforts were made to observe these modes through different techniques. The most promising is the monitoring of Doppler velocity images of the planet with a dedicated instrument. In 2011, a time series recorded with this method permitted the determination of a fundamental frequency present in the structure of the power spectrum and compatible with our knowledge of the Jovian internal structure. With a similar instrument, recent observations of Jupiter provided measurements of the 3 components of the wind at the surface of Jupiter, demonstrating its sensitivity. However, ground-based observations remain limited in resolution and duration. Such an instrument on a dedicated space mission would give unvaluable information.

During this talk we will present previous attempts to measure oscillations on Jupiter and Saturn from Earth and space. We will show the results and the remaining questions, including mode excitation and amplitudes. We will also review the present instrumental development and the most promising projects. Finally, we would derive a possible strategy for future observations in the frame of the international space mission context.

How to cite: Schmider, F.-X., Gaulme, P., Guillot, T., Jackiewicz, J., Markham, S., Doerr, H.-P., Morales-Juberías, R., Abe, L., Dejonghe, J., Simon, A., and Hsu, S.: Perspectives of Jovian seismology: sounding the interior of the Gas Giants through oscillations, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2569, https://doi.org/10.5194/egusphere-egu25-2569, 2025.

The James Webb Space Telescope observed the Jovian System during Cycle 1 through the Early Release Science program 1373 (de Pater et al. 2022). The NIRCAM instrument obtained high-spatial resolution observations of the Jovian atmosphere in July 2022 in 5 different filters in wavelengths from 1.6 to 4.1 microns, with observations in three filters repeated after one planetary rotation to asses winds and atmospheric dynamics. The combination of high sensitivity in the near infrared and spatial resolution provided images that reveal exciting new aspects of the Jovian atmosphere. Early results from those observations include the discovery of a fast and narrow equatorial jet in the upper hazes near the tropopause potentially related with Jupiter’s Equatorial Stratospheric Oscillation (Hueso et al. 2023), the wind field of the upper levels of the Great Red Spot (Harkett et al. 2024), and in exciting views of the polar hazes and auroras that may give us hints of their potential relations (Antuñano et al. 2024). Observations also show new features in the atmosphere, such as a detached limb brightening from fluorescent emissions similar to observations attained by the JIRAM instrument on Juno (Migliorini et al. 2023). The 405N image shows the deep troposphere combined in some areas with thermal emissions from the interior of the planet. We here review those images, discussing atmospheric dynamics retrieved from those observations through the planet at multiple altitudes beyond the equator and the polar areas and we present additional aspects revealed by these observations that, together with a few commissioning observations from program 1022, remain so far the unique NIRCAM observations of the Jupiter atmosphere.

References:

de Pater et al. JWST Observations of the Jovian System from Commissioning and ERS data . AAS Division of Planetary Science meeting #54, 2022. id. 306.07

Hueso et al. An intense narrow equatorial jet in Jupiter’s lower stratosphere observed by JWST, Nature Astronomy, 2023. https://doi.org/10.1038/s41550-023-02099-2

Harkett et al. Thermal Structure and Composition of Jupiter’s Great Red Spot from JWST/MIRI, Journal of Geophysical Research: Planets, 2024. https://doi.org/10.1029/2024JE008415

Antuñano et al. JWST/NIRCAM views of Jupiter's polar regions, EPSC Meeting Europlanet Science Congress 2024, id. EPSC2024-808.

Migliorini et al. First Observations of CH4 and H3+ Spatially Resolved Emission Layers at Jupiter Equator, as Seen by JIRAM/Juno, Journal of Geophysical Research: Planets, 2024. https://doi.org/10.1029/2022JE007509

How to cite: Hueso, R., Antunano, A., Sanchez-Lavega, A., Sanchez-Arregui, M., de Pater, I., Fouchet, T., Fletcher, L., Harkett, J., Orton, G., Rodríguez-Ovalle, P., Stansberry, J., and Wong, M.: The multiple layers of Jupiter’s troposphere observed by the NIRCAM instrument in the James Webb Space Telescope , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18631, https://doi.org/10.5194/egusphere-egu25-18631, 2025.

Starting from the Jupiter approach phase in early 2016, several Hubble Space Telescope observation campaigns dedicated to the UV aurorae have been executed in order to support the Juno mission. For example, these images have been used to study the auroral response to solar wind shocks measured by Juno's in situ instruments, or to identify the specific auroral morphologies associated with a compressed magnetosphere. In this presentation, we will focus on the images acquired simultaneously from Juno's UV spectrograph on one hand and from the Space Telescope Imaging Spectrograph on the other hand, each one looking at a different hemisphere. While the overall morphology is similar, variations of relative brightness between conjugate features, or shifts in the timing of some flares, are observed and are interpreted as signatures of distinct electron acceleration mechanisms or of magnetic field anomalies. Such combined observations thus provide unique insights into the asymmetries of the Jovian magnetosphere and its coupling with the ionosphere and upper atmosphere.

How to cite: Bonfond, B., Moirano, A., Benmahi, B., Grodent, D., Head, L., Sicorello, G., Gérard, J.-C., Greathouse, T., Glastone, R., Giles, R., Kammer, J., Hue, V., Yao, Z., Nichols, J., Badman, S., and Clarke, J.: A view from the other side: complementary observations of the Jovian UV aurorae from Hubble and Juno, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-21868, https://doi.org/10.5194/egusphere-egu25-21868, 2025.

We have been performing ground-based observations of Jupiter's sodium nebula longer than two decades. The sodium atoms in the nebula originate in Io's volcanic gas. The nebula distributes over 1,000 Jupiter's radii, and its angular size is approximately 10 degrees. Therefore, ground-based observations of D-line emissions in the sodium nebula can be made with small optics. The observation results indicate that the sodium D-line brightness in the nebula varies with various timescales like day-to-day through year-to-year. While it is naturally expected that variations in the brightness of the nebula reflect that of volcanism on Io, it may be influenced by locations of active volcanic plumes on Io. Sometimes, variations of the nebula differ between the eastern and western sides of Jupiter.  Details on the variations of Jupiter's extended sodium nebula will be shown. Especially, a period in which Juno spacecraft has been orbiting Jupiter will be focused. 

How to cite: Yoneda, M., Tsuchiya, F., Schmidt, C., Morgenthaler, J., Kagitani, M., and Sakanoi, T.: Variations in Jupiter's extended sodium nebula over two decades, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14285, https://doi.org/10.5194/egusphere-egu25-14285, 2025.