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Jupiter's Great Red Spot (GRS) was mapped by the James Webb Space Telescope (JWST)/Mid‐Infrared Instrument (4.9–27.9 μ${\upmu }$m) in July and August 2022. These observations took place alongside a suite of visual and infrared observations from; Hubble, JWST/NIRCam, Very Large Telescope/VISIR and amateur observers which provided both spatial and temporal context across the jovian disc. The stratospheric temperature structure retrieved using the NEMESIS software revealed a series of hot‐spots above the GRS. These could be the consequence of GRS‐induced wave activity. In the troposphere, the temperature structure was used to derive the thermal wind structure of the GRS vortex. These winds were only consistent with the independently determined wind field by JWST/NIRCam at 240 mbar if the altitude of the Hubble‐derived winds were located around 1,200 mbar, considerably deeper than previously assumed. No enhancement in ammonia was found within the GRS but a link between elevated aerosol and phosphine abundances was observed within this region. North‐south asymmetries were observed in the retrieved temperature, ammonia, phosphine and aerosol structure, consistent with the GRS tilting in the north‐south direction. Finally, a small storm was captured north‐west of the GRS that displayed a considerable excess in retrieved phosphine abundance, suggestive of vigorous convection. Despite this, no ammonia ice was detected in this region. The novelty of JWST required us to develop custom‐made software to resolve challenges in calibration of the data. This involved the derivation of the “FLT‐5” wavelength calibration solution that has subsequently been integrated into the standard calibration pipeline. Regularly observed for over 150 years, Jupiter's Great Red Spot (GRS) is one of the best documented storms in the Solar System. Despite the frequency of observations, crucial questions remain unanswered regarding the internal composition, dynamics and driving mechanism for the storm. Mid‐infrared observations acquired by the James Webb Space Telescope allowed us to peer past the colorful clouds to assess the composition and dynamics of the jovian weather layer. Data from the mid‐infrared instrument was modeled in the 7.30–10.75 μ${\upmu }$m range to “retrieve” the temperature distribution. Further modeling of these temperatures allowed us to derive the wind speeds throughout the vortex, enabling us to assess the dynamics of the GRS and how the vortex interacts with its surroundings. In addition, a series of hot‐spots were observed above the GRS that could be the result of atmospheric wave activity. The distribution of ammonia was also mapped in this spectral range. Comparison of the distribution of ammonia to the cloud distribution implied that this molecule may condense into the thick layers of cloud above the GRS. Finally phosphine, indicative of upwelling air was mapped and allowed us to identify a small convective storm north‐west of the GRS. Jupiter's Great Red Spot (GRS) was observed by James Webb Space Telescope/Mid‐Infrared Instrument in 2022 to study the 3D structure of temperature, aerosols and gaseous speciesA series of stratospheric hot‐spots were discovered to be co‐moving with the GRS in the longitude directionElevated phosphine and a complex distribution of ammonia gas were observed inside the GRS Jupiter's Great Red Spot (GRS) was observed by James Webb Space Telescope/Mid‐Infrared Instrument in 2022 to study the 3D structure of temperature, aerosols and gaseous species A series of stratospheric hot‐spots were discovered to be co‐moving with the GRS in the longitude direction Elevated phosphine and a complex distribution of ammonia gas were observed inside the GRS

High spatial resolution images of Jupiter at 1.58–2.28 μm are used to track and characterize a wave pattern observed in 2017 at a planetocentric latitude of 14°N. The wave pattern has a wave number of 18 and spans ∼5° in latitude. One bright crest remains stationary in System III longitude, while the remaining crests move slowly westward. The bright and dark regions of the near‐infrared wave pattern are caused by variations in the vertical location of the upper tropospheric haze layer. A comparison with thermal infrared observations shows a correlation with temperature anomalies in the upper troposphere. The results are consistent with a Rossby wave, generated by flow around a stationary vortex. The Gemini North telescope was used to take high spatial resolution images of Jupiter in the near‐infrared during 2017–2018. These images can be used to track the complex movement of hazes in Jupiter's upper atmosphere. The timing of these observations is particularly relevant because the Juno mission is currently in orbit around Jupiter, and near‐infrared images of the entire planet's disk can be used to place the measurements from Juno's instruments in a broader context. In this paper, we focus on a particularly prominent atmospheric feature that was observed during this time period: a bright wave pattern in Jupiter's northern hemisphere. We track the movement of this wave pattern with time, we study its three‐dimensional structure, and we compare these near‐infrared observations with images taken in the visible and thermal infrared. We find that the wave is consistent with a Rossby wave, generated by flow around a stationary vortex. These results can be used to inform future numerical simulations of Jupiter's atmosphere, helping us to understand the dynamics that drive the planet's complex weather patterns. Near‐infrared images of Jupiter are used to track the evolution of a wave pattern in the planet's North Equatorial BeltThe wave pattern has a wave number of ∼18, is located at 12–17°N, and moves slowly westwardThe bright and dark regions of the wave are caused by variations in the vertical location of the upper tropospheric haze layer

In October and November 2014, spectra covering the 1.436 to 1.863‐μm wavelength range from the SINFONI Integral Field Unit Spectrometer on the Very Large Telescope showed the presence of a vast bright north polar cap on Uranus, extending northward from about 40°N and at all longitudes observed. The feature, first detected in August 2014 from Keck telescope images, has a morphology very similar to the southern polar cap that was seen to fade before the 2007 equinox. At strong methane‐absorbing wavelengths (for which only the high troposphere or stratosphere is sampled) the feature is not visible, indicating that it is not a stratospheric phenomenon. We show that the observed northern bright polar cap results mainly from a decrease in the tropospheric methane mixing ratio, rather than from a possible latitudinal variation of the optical properties or abundance of aerosol, implying an increase in polar downwelling near the tropopause level. In this paper we show that Uranus's northern polar cap in 2014 results from a hole‐like depletion of methane rather than a formation or accumulation of aerosols as was previously thought. In this regard, our results provide key insights on the Uranus postequinox circulation as well as on the formation and nature of the different bright features observed before and after 2007 equinox in both hemispheres. The polar cap observed in 2014 results from a decrease in the tropospheric methane mixing ratioVery similar haze and cloud scattering properties are observed at latitudes within and far away from the polar cap

Hubble Space Telescope Wide‐Field Camera 3 (HST/WFC3) observations spanning 2015 to 2021 confirm a brightening of Uranus' north polar hood feature with time. The vertical aerosol model of Irwin et al. (2023, https://doi.org/10.1038/s41550-023-02047-0) (IRW23), consisting of a deep haze layer based at ∼5 bar, a 1–2 bar haze layer, and an extended haze rising up from the 1–2 bar layer, was applied to retrievals on HST Space Telescope Imaging Spectrograph (STIS) (HST/STIS) observations (Sromovsky et al., 2014, 2019, https://doi.org/10.1016/j.icarus.2014.05.016, https://doi.org/10.1016/j.icarus.2018.06.026) revealing a reduction in cloud‐top CH4volume mixing ratio (VMR) (i.e., above the deep ∼5 bar haze) by an average of 0.0019 ± 0.0003 between 40–80◦N (∼10% average reduction) from 2012 to 2015. A combination of latitudinal retrievals on the HST/WFC3 and HST/STIS data sets, again employing the IRW23 model, reveal a temporal thickening of the 1–2 bar haze layer to be the main cause of the polar hood brightening, finding an average increase in integrated opacity of 1.09 ± 0.08 (∼33% increase) at 0.8 µm north of ∼45°N, concurrent with a decrease in the imaginary refractive index spectrum of the 1–2 bar haze layer north of ∼40°N and longwards of ∼0.7 µm. Small contributions to the brightening were found from a thickening of the deep aerosol layer, with an average increase in integrated opacity of 0.6 ± 0.1 (58% increase) north of 45°N between 2012 and 2015, and from the aforementioned decrease in CH4VMR. Our results are consistent with the slowing of a stratospheric meridional circulation, exhibiting subsidence at the poles. Uranus' north polar hood—a bright cap‐like feature encircling the northern polar region within its atmosphere—is observed to be brightening over time. Using several observations of Uranus captured between 2012 and 2021 by the Hubble Space Telescope, this study aims to pinpoint, for the first time, the specific changes occurring within the atmosphere leading to this evolution. Analysis of the observations confirmed the predominant cause of the hood's brightening to be changes in the scattering properties of the atmosphere's aerosol layers. A vertical aerosol model consisting of 3 distinct haze layers was employed to investigate these changes. We find that the hood's brightening mainly stems from changes in the middle haze layer in the model (centered at 1–2 bar), finding a thickening of this layer concurrent with an increase in the reflectivity of its aerosols over time at latitudes coincident with the north polar hood (∼45–90°N). Small contributions to the temporal brightening were also found from a ∼10% reduction in cloud‐top methane and a thickening of the deepest haze layer in the model (centered at ∼5 bar) at north polar hood latitudes. We confirm that the brightening of Uranus' north polar hood is predominantly due to changes in aerosol scatteringA temporal thickening and increase in aerosol reflectivity of Irwin et al. (2023, https://doi.org/10.1038/s41550-023-02047-0)'s 1–2 bar haze is the main cause of the brighteningWe find a further reduction in polar cloud‐top methane over time from retrievals carried out on Hubble Space Telescope's/Space Telescope Imaging Spectrograph observations We confirm that the brightening of Uranus' north polar hood is predominantly due to changes in aerosol scattering A temporal thickening and increase in aerosol reflectivity of Irwin et al. (2023, https://doi.org/10.1038/s41550-023-02047-0)'s 1–2 bar haze is the main cause of the brightening We find a further reduction in polar cloud‐top methane over time from retrievals carried out on Hubble Space Telescope's/Space Telescope Imaging Spectrograph observations

In this study, we present the evolution of the properties and vertical distribution of the hazes in Jupiter's Great Red Spot (GRS), its surroundings and Oval BA from 2015 to 2021. To retrieve the main atmospheric parameters, we model the spectral reflectivity of a number of dynamically and/or spectrally interesting regions with a radiative transfer tool that uses an optimal estimator scheme. The spectra of the selected regions are obtained from high‐resolution Hubble Space Telescope Wide Field Camera 3 images that cover the spectral range from 200 to 900 nm. The a priori model atmosphere used to describe the various Jovian regions is taken from Anguiano‐Arteaga et al. (2021, https://doi.org/10.1029/2021JE006996) for each corresponding area. We find that the biggest variations in the GRS occur in the optical thickness of the stratospheric and tropospheric haze layers starting in 2019 and in the mean size of the tropospheric haze particles in 2018. The absorption spectra of both hazes show little variations among the analyzed regions and years, with the stratospheric haze properties seeming compatible with the chromophore proposed by Carlson et al. (2016, https://doi.org/10.1016/j.icarus.2016.03.008). We report a color change of Oval BA from red to white during these years that, according to our models, can be mostly explained in terms of a decrease in the stratospheric haze optical depth. The Great Red Spot of Jupiter (GRS) is the largest and longest‐lived anticyclone in the solar system atmospheres. Despite having been widely studied, the nature of the aerosol(s) giving the spot its characteristic red color is still unknown, as well as the relation of their creation/destruction mechanisms with dynamics. In 2019, the Great Red Spot started a series of interactions with smaller anticyclones that may have changed its vertical cloud structure, which made the region particularly worthy for our analysis. At the same time, the second largest anticyclone in Jupiter, called Oval BA, changed its color from red to white in 2018, something that also happened in the past (but from white to red) and deserved some attention. We used Hubble Space Telescope images to constrain models of the vertical structure and some relevant atmospheric properties of the hazes in the GRS, its surroundings and Oval BA. We found that most of the changes are related to the thickness of the uppermost coloring layer in the atmosphere, being able to reproduce the observed reflectivity and its temporal and spatial variations. The nature of this layer seems to be compatible with compounds resulting from photochemical reactions in the upper atmosphere. A model of the visible reflectivity of the Great Red Spot and its surroundings from 2015 to 2021 shows no significant changesOur analysis suggests the presence of two coloring aerosols, the upper one compatible with the chromophore proposed by Carlson et al. (2016, https://doi.org/10.1016/j.icarus.2016.03.008)We find that the Oval BA color change between 2016 and 2020 is due to a decrease in the optical thickness of the upper haze A model of the visible reflectivity of the Great Red Spot and its surroundings from 2015 to 2021 shows no significant changes Our analysis suggests the presence of two coloring aerosols, the upper one compatible with the chromophore proposed by Carlson et al. (2016, https://doi.org/10.1016/j.icarus.2016.03.008) We find that the Oval BA color change between 2016 and 2020 is due to a decrease in the optical thickness of the upper haze

Thin-film transmission spectra of ammonium hydrosulfide (NH_4SH) ice and ammonia (NH_3) ice between 1300 and 12,000 cm^−1 were used to determine the ice's optical constants. The films were grown on a sapphire substrate, and a Fourier-transform spectrometer and a grating spectrometer were used together to record the spectra. Lambert's law was used to directly determine the imaginary component of the complex refractive indices; from this, the real component was derived using the Kramers-Kronig algorithm. It is shown that, contrary to what is expected, the optical constants determined for NH_3 ice at 80 K are in good agreement with those in the cubic phase, rather than the metastable one. The phase of the NH_4SH ice was observed to change from amorphous to polycrystalline as the film was annealed to 160 K.

Isotopic ratios in atmospheric CO2are shaped by various processes throughout Mars' history, and can help understand what the atmosphere of early Mars was like to sustain liquid water on its surface. In this study, we monitor the O and C isotopic composition of CO2between 70 and 130 km for more than half a Martian year using solar occultation observations by the Atmospheric Chemistry Suite onboard the ExoMars Trace Gas Orbiter. We find the vertical trends of the isotopic ratios to be consistent with the expectations from diffusive separation above the homopause, with average values below this altitude being consistent with Earth‐like fractionation (δ13C = −3 ± 37‰; δ18O = −29 ± 38‰; and δ17O = −11 ± 41‰). Using these measurements, we estimate that at least 20%–40% of primordial C on Mars has escaped to space throughout history. The total amount of C lost from the atmosphere is likely to be well in excess of this lower limit, due to carbonate formation and further sink processes. In addition, we propose a photochemical transfer of light O from H2O to CO2to explain the larger enrichment in the O18/O16${}^{18}\mathrm{O}/{}^{16}\mathrm{O}$ratio in H2O than in CO2. There is ample evidence suggesting that liquid water was abundant on the surface of Mars in the past. However, climatic conditions on early Mars must have been very different from the ones we observe today to sustain liquid water on its surface. The ratios of the heavy and light isotopes in different species provide a very useful tool to estimate the early climate of Mars. In this study, we monitor the isotopic ratios of carbon dioxide in the atmosphere of Mars to provide more accurate estimates of these. With our measurements, and in context with previous studies, we estimate that at least 20%–40% of the carbon reservoir has been lost to space throughout Martian history. This, together with the sequestration of atmospheric C on the surface in the form of minerals, is consistent with the idea that the atmosphere of early Mars was denser than the one we observe today. Isotopic ratios in CO2are observed to be consistent with telluric standards and to fractionate by diffusive separation above the homopauseAt least 20%–40% of the C reservoir has escaped to space throughout Martian historyThe higher 18O/16O ratio in H2O than in CO2may be explained by a photochemical transfer of lighter O from H2O to CO2 Isotopic ratios in CO2are observed to be consistent with telluric standards and to fractionate by diffusive separation above the homopause At least 20%–40% of the C reservoir has escaped to space throughout Martian history The higher 18O/16O ratio in H2O than in CO2may be explained by a photochemical transfer of lighter O from H2O to CO2

In this work, we have analyzed images provided by the Hubble Space Telescope's Wide Field Camera 3 (HST/WFC3) in December 2016, with a spectral coverage from the ultraviolet to the near infrared. We have obtained the spectral reflectivity of the GRS and its surroundings, with particular emphasis on selected, dynamically interesting regions. A spectral characterization of the GRS area is performed following two different procedures: (a) in terms of Altitude/Opacity and Color Indices (AOI and CI); (b) by means of automatic spectral classification. We used the NEMESIS radiative transfer suite to retrieve the main atmospheric parameters (e.g., particle vertical and size distributions, refractive indices) that are able to explain the observed spectral reflectivity. The optimal a priorimodel atmosphere used for the retrievals is obtained from a grid of about 12,000 different atmospheric models, and choosing the one that best fits South Tropical Zone (STrZ) spectra and its observed limb‐darkening. We conclude that the spectral reflectivity of the GRS area is well reproduced with the following layout: (a) a stratospheric haze with its base near the 100 mbar level, with optical depths at 900 nm of the order of unity and particles with a size of 0.3 μm; (b) a more vertically extended tropospheric haze, with τ (900 nm) ∼10 down to 500 mbar and micron sized particles. Both haze layers show a stronger short wavelength absorption, and thus both act as chromophores. The altitude difference between clouds tops in the GRS and surrounding areas is ∼10 km. One of the main questions concerning the Great Red Spot (GRS) of Jupiter is the origin of its reddish color. It is commonly understood that the cause of this feature are one or more unknown species of aerosols located in the upper atmosphere. Even in the whitest areas of Jupiter, stronger blue light absorption has been measured, suggesting the global presence of one or more species of blue absorbing aerosols. We use Hubble Space Telescope (HST) observations to retrieve atmospheric models describing the vertical structure and some of the main atmospheric properties of the hazes in the GRS and its surrounding area. Our results suggest that two different blue absorbing aerosols are able to account for the color of the GRS and its vicinity. We model the visible reflectivity of the Great Red Spot and surrounding regions in December 2016We retrieve a stratospheric haze above an optically thick tropospheric haze layer, both with a strong short wavelength absorptionThe retrieved stratospheric haze seems to be compatible with the chromophore proposed by Carlson et al. (2016) We model the visible reflectivity of the Great Red Spot and surrounding regions in December 2016 We retrieve a stratospheric haze above an optically thick tropospheric haze layer, both with a strong short wavelength absorption The retrieved stratospheric haze seems to be compatible with the chromophore proposed by Carlson et al. (2016)

The Ultraviolet Spectrograph (UVS) instrument on the Juno mission records far‐ultraviolet reflected sunlight from Jupiter. These spectra are sensitive to the abundances of chemical species in the upper atmosphere and to the distribution of the stratospheric haze layer. We combine observations from the first 30 perijoves of the mission in order to study the meridional distribution of acetylene (C2H2) in Jupiter's stratosphere. We find that the abundance of C2H2decreases toward the poles by a factor of 2–4, in agreement with previous analyses of mid‐infrared spectra. This result is expected from insolation rates: near the equator, the UV solar flux is higher, allowing more C2H2to be generated from the UV photolysis of CH4. The decrease in abundance toward the poles suggests that horizontal mixing rates are not rapid enough to homogenize the latitudinal distribution. The Ultraviolet Spectrograph instrument on the Juno mission to Jupiter is primarily used to study the planet's ultraviolet auroras, but also records reflected sunlight from the planet's upper atmosphere. These ultraviolet reflected sunlight observations can be used to measure the abundances of different gases in Jupiter's stratosphere. In this study, we focus on one prominent molecule, acetylene, and study how its abundance varies with latitude. We find that its abundance decreases toward Jupiter's poles, which agrees with previous results obtained from studying the same molecule with infrared observations. Ultraviolet reflected sunlight observations from Juno Ultraviolet Spectrograph were used to study the C2H2abundance in Jupiter's stratosphereThe stratospheric C2H2abundance decreases at high latitudes, in agreement with previous studies using infrared dataThe latitudinal distribution of C2H2can be used to constrain horizontal mixing rates Ultraviolet reflected sunlight observations from Juno Ultraviolet Spectrograph were used to study the C2H2abundance in Jupiter's stratosphere The stratospheric C2H2abundance decreases at high latitudes, in agreement with previous studies using infrared data The latitudinal distribution of C2H2can be used to constrain horizontal mixing rates

The James Webb Space Telescope(JWST) presents the opportunity to transform our understanding of planets and the origins of life by revealing the atmospheric compositions, structures, and dynamics of transiting exoplanets in unprecedented detail. However, the high-precision, timeseries observations required for such investigations have unique technical challenges, and prior experience with Hubble, Spitzer, and other facilities indicates that there will be a steep learning curve when JWSTbecomes operational. In this paper, we describe the science objectives and detailed plans of the Transiting Exoplanet Community Early Release Science (ERS) Program, which is a recently approved program for JWSTobservations early in Cycle 1. We also describe the simulations used to establish the program. The goal of this project, for which the obtained data will have no exclusive access period, is to accelerate the acquisition and diffusion of technical expertise for transiting exoplanet observations with JWST, while also providing a compelling set of representative data sets that will enable immediate scientific breakthroughs. The Transiting Exoplanet Community ERS Program will exercise the timeseries modes of all four JWSTinstruments that have been identified as the consensus highest priorities, observe the full suite of transiting planet characterization geometries (transits, eclipses, and phase curves), and target planets with host stars that span an illustrative range of brightnesses. The observations in this program were defined through an inclusive and transparent process that had participation from JWSTinstrument experts and international leaders in transiting exoplanet studies. The targets have been vetted with previous measurements, will be observable early in the mission, and have exceptional scientific merit. Community engagement in the project will be centered on a two-phase Data Challenge that culminates with the delivery of planetary spectra, timeseries instrument performance reports, and open-source data analysis toolkits in time to inform the agenda for Cycle 2 of the JWSTmission.

Jupiter's tropospheric ammonia (NH3) abundance is studied using spatially resolved 5 μm observations from the cryogenic high‐resolution infrared spectrograph (CRIRES) at the European Southern Observatory's Very Large Telescope. The high‐resolving power (R= 96,000) allows the line shapes of three NH3absorption features to be resolved. We find that within the 1–4 bar pressure range, the NH3abundance decreases with altitude. The instrument slit was aligned north‐south along Jupiter's central meridian, allowing us to search for latitudinal variability. There is considerable uncertainty in the large‐scale latitudinal variability, as the increase in cloud opacity in zones compared to belts can mask absorption features. However, we do find evidence for a strong NH3enhancement at 4–6°N, consistent with a localized “ammonia plume” on the southern edge of Jupiter's North Equatorial Belt. Jupiter's tropospheric ammonia abundance is studied using high‐resolution 5 micrometer spectroscopy from VLT/CRIRESThe ammonia abundance decreases with altitude in the 1–4 bar pressure range at all latitudesThere is a strong localized enhancement in ammonia abundance at 4–6°N

We provide a revised Table 5 for the paper by Nixon et al. [Appl. Opt.48, 1912 (2009)APOPAI0003-693510.1364/AO.48.001912], in which the abundances of CO_213 and C^18O were incorrect.

This white paper examines the benefit of the upcoming James Webb Space Telescope(JWST) for studies of the Solar System's four giant planets: Jupiter, Saturn, Uranus, and Neptune. JWST's superior sensitivity, combined with high spatial and spectral resolution, will enable near- and mid-infrared imaging and spectroscopy of these objects with unprecedented quality. In this paper, we discuss some of the myriad scientific investigations possible with JWSTregarding the giant planets. This discussion is preceded by the specifics of JWSTinstrumentation most relevant to giant-planet observations. We conclude with identification of desired pre-launch testing and operational aspects of JWSTthat would greatly benefit future studies of the giant planets.