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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. Plain Language Summary: 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. Key Points: 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 [ABSTRACT FROM AUTHOR]

Spectroscopic phase curves of hot Jupiters measure their emission spectra at multiple orbital phases, thus enabling detailed characterization of their atmospheres. Precise constraints on the atmospheric composition of these exoplanets offer insights into their formation and evolution. We analyse four phase-resolved emission spectra of the hot Jupiter WASP-43b, generated from a phase curve observed with the Mid-Infrared Instrument/Low Resolution Spectrometer onboard the JWST , to retrieve its atmospheric properties. Using a parametric 2D temperature model and assuming a chemically homogeneous atmosphere within the observed pressure region, we simultaneously fit the four spectra to constrain the abundances of atmospheric constituents, thereby yielding more precise constraints than previous work that analysed each spectrum independently. Our analysis reveals statistically significant evidence of NH |$_3$| (4 |$\sigma$|⁠) in a hot Jupiter's emission spectra for the first time, along with evidence of H |$_2$| O (6.5 |$\sigma$|⁠), CO (3.1 |$\sigma$|⁠), and a non-detection of CH |$_4$|⁠. With our abundance constraints, we tentatively estimate the metallicity of WASP-43b at 0.6 |$-6.5\times$| solar and its C/O ratio at 0.6 |$-$| 0.9. Our findings offer vital insights into the atmospheric conditions and formation history of WASP-43b by simultaneously constraining the abundances of carbon, oxygen, and nitrogen-bearing species. [ABSTRACT FROM AUTHOR]

We present a quantitative analysis of the seasonal record of Uranus's disc-averaged colour and photometric magnitude in Strömgren b and y filters (centred at 467 and 551 nm, respectively), recorded at the Lowell Observatory from 1950 to 2016, and supplemented with HST /WFC3 observations from 2016 to 2022. We find that the seasonal variations of magnitude can be explained by the lower abundance of methane at polar latitudes combined with a time-dependent increase of the reflectivity of the aerosol particles in layer near the methane condensation level at 1 – 2 bar. This increase in reflectivity is consistent with the addition of conservatively scattering particles to this layer, for which the modelled background haze particles are strongly absorbing at both blue and red wavelengths. We suggest that this additional component may come from a higher proportion of methane ice particles. We suggest that the increase in reflectivity of Uranus in both filters between the equinoxes in 1966 and 2007, noted by previous authors, might be related to Uranus's distance from the Sun and the production rate of dark photochemical haze products. Finally, we find that although the visible colour of Uranus is less blue than Neptune, due to the increased aerosol thickness on Uranus, and this difference is greatest at Uranus's solstices, it is much less significant than is commonly believed due to a long-standing misperception of Neptune's 'true' colour. We describe how filter-imaging observations, such as those from Voyager-2/ISS and HST /WFC3, should be processed to yield accurate true colour representations. [ABSTRACT FROM AUTHOR]

Spectroscopic phase curves of transiting hot Jupiters are spectral measurements at multiple orbital phases, giving a set of disc-averaged spectra that probe multiple hemispheres. By fitting model phase curves to observations, we can constrain the atmospheric properties of hot Jupiters, such as molecular abundance, aerosol distribution, and thermal structure, which offer insights into their atmospheric dynamics, chemistry, and formation. We propose a novel 2D temperature parametrization consisting of a dayside and a nightside to retrieve information from near-infrared phase curves and apply the method to phase curves of WASP-43b observed by HST /Wide Field Camera 3 and Spitzer /Infra-Red Array Camera. In our scheme, the temperature is constant on isobars on the nightside and varies with cos n (longitude/ϵ) on isobars on the dayside, where n and ϵ are free parameters. We fit all orbital phases simultaneously using the radiative transfer package nemesispy coupled to a Bayesian inference code. We first validate the performance of our retrieval scheme with synthetic phase curves generated from a Global Circulation Model and find that our 2D scheme can accurately retrieve the latitudinally averaged thermal structure and constrain the abundance of H2O and CH4. We then apply our 2D scheme to the observed phase curves of WASP-43b and find: (1) The dayside temperature–pressure profiles do not vary strongly with longitude and are non-inverted. (2) The retrieved nightside temperatures are extremely low, suggesting significant nightside cloud coverage. (3) The H2O volume mixing ratio is constrained to 5.6 × 10−5–4.0 × 10−4, and we retrieve an upper bound for CH4 mixing ratio at ∼10−6. [ABSTRACT FROM AUTHOR]

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 CH4 volume 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 CH4 VMR. Our results are consistent with the slowing of a stratospheric meridional circulation, exhibiting subsidence at the poles. Plain Language Summary: 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. Key Points: 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 [ABSTRACT FROM AUTHOR]

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. Plain Language Summary: 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. Key Points: 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 [ABSTRACT FROM AUTHOR]

Isotopic ratios in atmospheric CO2 are 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 CO2 between 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 CO2 to explain the larger enrichment in the O18/O16 ${}^{18}\mathrm{O}/{}^{16}\mathrm{O}$ ratio in H2O than in CO2. Plain Language Summary: 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. Key Points: Isotopic ratios in CO2 are 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 CO2 may be explained by a photochemical transfer of lighter O from H2O to CO2 [ABSTRACT FROM AUTHOR]

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 priori model 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. Plain Language Summary: 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. Key Points: 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) [ABSTRACT FROM AUTHOR]

Observational studies of exoplanets are suggestive of a ubiquitous presence of clouds. The current modelling techniques used in emission to account for the clouds tend to require prior knowledge of the cloud condensing species and often do not consider the scattering effects of the cloud. We explore the effects that thermal scattering has on the emission spectra by modelling a suite of hot Jupiter atmospheres with varying cloud single-scattering albedos (SSAs) and temperature profiles. We examine cases ranging from simple isothermal conditions to more complex structures and physically driven cloud modelling. We show that scattering from nightside clouds would lead to brightness temperatures that are cooler than the real atmospheric temperature if scattering is unaccounted for. We show that scattering can produce spectral signatures in the emission spectrum even for isothermal atmospheres. We identify the retrieval degeneracies and biases that arise in the context of simulated JWST spectra when the scattering from the clouds dominates the spectral shape. Finally, we propose a novel method of fitting the SSA spectrum of the cloud in emission retrievals, using a technique that does not require any prior knowledge of the cloud chemical or physical properties. [ABSTRACT FROM AUTHOR]

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 C2H2 decreases 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 C2H2 to 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. Plain Language Summary: 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. Key Points: Ultraviolet reflected sunlight observations from Juno Ultraviolet Spectrograph were used to study the C2H2 abundance in Jupiter's stratosphereThe stratospheric C2H2 abundance decreases at high latitudes, in agreement with previous studies using infrared dataThe latitudinal distribution of C2H2 can be used to constrain horizontal mixing rates [ABSTRACT FROM AUTHOR]

Exoplanet emission spectra are often modelled assuming that the hemisphere observed is well represented by a horizontally homogenized atmosphere. However, this approximation will likely fail for planets with a large temperature contrast in the James Webb Space Telescope (JWST) era, potentially leading to erroneous interpretations of spectra. We first develop an analytic formulation to quantify the signal-to-noise ratio and wavelength coverage necessary to disentangle temperature inhomogeneities from a hemispherically averaged spectrum. We find that for a given signal-to-noise ratio, observations at shorter wavelengths are better at detecting the presence of inhomogeneities. We then determine why the presence of an inhomogeneous thermal structure can lead to spurious molecular detections when assuming a fully homogenized planet in the retrieval process. Finally, we quantify more precisely the potential biases by modelling a suite of hot Jupiter spectra, varying the spatial contributions of a hot and a cold region, as would be observed by the different instruments of JWST /NIRSpec. We then retrieve the abundances and temperature profiles from the synthetic observations. We find that in most cases, assuming a homogeneous thermal structure when retrieving the atmospheric chemistry leads to biased results, and spurious molecular detection. Explicitly modelling the data using two profiles avoids these biases, and is statistically supported provided the wavelength coverage is wide enough, and crucially also spanning shorter wavelengths. For the high contrast used here, a single profile with a dilution factor performs as well as the two-profile case, with only one additional parameter compared to the 1D approach. [ABSTRACT FROM AUTHOR]

We present a novel retrieval technique that attempts to model phase curve observations of exoplanets more realistically and reliably, which we call the 2.5-dimensional (2.5D) approach. In our 2.5D approach we retrieve the vertical temperature profile and mean gaseous abundance of a planet at all longitudes and latitudes simultaneously, assuming that the temperature or composition, x , at a particular longitude and latitude (Λ, Φ) is given by |$x(\Lambda ,\Phi) = \bar{x} + (x(\Lambda ,0) - \bar{x})\cos ^n\Phi$|⁠ , where |$\bar{x}$| is the mean of the morning and evening terminator values of x (Λ, 0), and n is an assumed coefficient. We compare our new 2.5D scheme with the more traditional 1D approach, which assumes the same temperature profile and gaseous abundances at all points on the visible disc of a planet for each individual phase observation, using a set of synthetic phase curves generated from a GCM-based simulation. We find that our 2.5D model fits these data more realistically than the 1D approach, confining the hotter regions of the planet more closely to the dayside. We then apply both models to WASP-43b phase curve observations of HST /WFC3 and Spitzer /IRAC. We find that the dayside of WASP-43b is apparently much hotter than the nightside and show that this could be explained by the presence of a thick cloud on the nightside with a cloud top at pressure <0.2 bar. We further show that while the mole fraction of water vapour is reasonably well constrained to (1–10) × 10−4, the abundance of CO is very difficult to constrain with these data since it is degenerate with temperature and prone to possible systematic radiometric differences between the HST /WFC3 and Spitzer /IRAC observations. Hence, it is difficult to reliably constrain C/O. [ABSTRACT FROM AUTHOR]

Current observational data of exoplanets are providing increasing detail of their 3D atmospheric structures. As characterization efforts expand in scope, the need to develop consistent 3D radiative-transfer methods becomes more pertinent as the complex atmospheric properties of exoplanets are required to be modelled together consistently. We aim to compare the transmission and emission spectra results of a 3D Monte Carlo radiative transfer (MCRT) model to contemporary radiative-transfer suites. We perform several benchmarking tests of an MCRT code, Cloudy Monte Carlo Radiative Transfer (cmcrt), to transmission and emission spectra model output. We add flexibility to the model through the use of k -distribution tables as input opacities. We present a hybrid MCRT and ray tracing methodology for the calculation of transmission spectra with a multiple scattering component. cmcrt compares well to the transmission spectra benchmarks at the 10s of ppm level. Emission spectra benchmarks are consistent to within 10 per cent of the 1D models. We suggest that differences in the benchmark results are likely caused by geometric effects between plane-parallel and spherical models. In a practical application, we post-process a cloudy 3D HD 189733b GCM model and compare to available observational data. Our results suggest the core methodology and algorithms of cmcrt produce consistent results to contemporary radiative transfer suites. 3D MCRT methods are highly suitable for detailed post-processing of cloudy and non-cloudy 1D and 3D exoplanet atmosphere simulations in instances where atmospheric inhomogeneities, significant limb effects/geometry or multiple scattering components are important considerations. [ABSTRACT FROM AUTHOR]

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. Plain Language Summary: 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. Key Points: 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 [ABSTRACT FROM AUTHOR]