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It is generally believed that variations in the upstream solar wind (SW) and interplanetary magnetic field (IMF) conditions are the main cause of changes of Jupiter's magnetopause (JM) location. However, most previous pressure balance models for the JM are axisymmetric and do not consider internal drivers, for example, the dynamics of the magnetodisc. We use three‐dimensional global magnetosphere simulations to investigate the variation of the JM under constant SW/IMF conditions. These simulations show that even without variations in the upstream driving conditions, the JM can exhibit dynamic variations, suggesting a range as large as 50 Jupiter radii in the subsolar location. Our study shows that the interchange structures in the Jovian magnetodisc will introduce significant radial dynamic pressure, which can drive significant variation in the JM location. The results provide important new context for interpreting the JM location and dynamics, with key implications for other internally mass‐loaded and/or rapidly rotating systems. Plain Language Summary The location of Jupiter's magnetopause is impacted by both external and internal conditions. In observations, the location of Jupiter's magnetopause has been found to change greatly and rapidly. This variation is generally believed to be caused by the significant changes in the external conditions. However, to‐date models and simulations have been mostly axisymmetric and static for the internal environment. Therefore, today, there is no interpretation that the internal mechanisms are sufficient to drive the drastic variation of Jupiter's magnetopause. In fact, because of the rapid rotation of Jupiter, as well as the particle outflow caused by volcanism on Jupiter's moon Io, the internal environment of Jupiter's magnetosphere is quite active. It is possible that the activity of the internal magnetospheric environment has a greater impact on Jupiter's magnetopause. We used three‐dimensional global simulations to investigate the variation of Jupiter's magnetopause under constant external conditions. The results show that even under constant external conditions, Jupiter's magnetopause will be highly impacted by internal conditions. Our study reveals the importance of the internal magnetospheric environment for the variation of Jupiter's magnetopause, even the whole magnetospheric system. Key Points The variation range of Jovian subsolar magnetopause standoff distance is very large even under constant solar wind conditions Interchange structures in the Jovian magnetodisc may affect the location of the magnetopause Significant radial dynamic pressure inside the Jovian magnetosphere may be the root cause of the variations of magnetopause

JIRAM is an imager/spectrometer on board the Juno spacecraft bound for a polar orbit around Jupiter. JIRAM is composed of IR imager and spectrometer channels. Its scientific goals are to explore the Jovian aurorae and the planet’s atmospheric structure, dynamics and composition. This paper explains the characteristics and functionalities of the instrument and reports on the results of ground calibrations. It discusses the main subsystems to the extent needed to understand how the instrument is sequenced and used, the purpose of the calibrations necessary to determine instrument performance, the process for generating the commanding sequences, the main elements of the observational strategy, and the format of the scientific data that JIRAM will produce.

The determination of Jupiter’s odd gravitational harmonics by the Juno spacecraft reveals that the observed jet streams extend to about three thousand kilometres below the cloud tops. Probing the depths of Jupiter The Juno mission set out to probe the hidden properties of Jupiter, such as its gravitational field, the depth of its atmospheric jets and its composition beneath the clouds. A collection of papers in this week's issue report some of the mission's key findings. Jupiter's gravitational field varies from pole to pole, but the cause of this asymmetry is unknown. Rotating planets that are squashed at the poles like Jupiter can have a gravity field that is characterized by a solid-body component, plus components that arise from motions in the atmosphere. Luciano Iess and colleagues use Juno's Doppler tracking data to determine Jupiter's gravity harmonics. They find that the north–south asymmetry arises from atmospheric and interior wind flows. To determine the depths of these flows, Yohai Kaspi and colleagues analyse the odd gravitational harmonics and find that the J 3 , J 5 , J 7 and J 9 harmonics are consistent with the jets extending deep into the atmosphere, perhaps as far as 3,000 kilometres. They conclude that the mass of Jupiter's dynamical atmosphere is about one per cent of Jupiter's total mass. The composition of Jupiter beneath its turbulent atmosphere remains a mystery. If different parts of a spinning object rotate at different rates, then the object probably has a fluid composition. Tristan Guillot and colleagues study the even gravitational harmonics and find that, below a depth of about 3,000 kilometres, Jupiter is rotating almost as a solid body. The atmospheric zonal flows extend downwards by more than 2,000 kilometres, but not beyond 3,500 kilometres, as is also the case with the jets. The depth to which Jupiter’s observed east–west jet streams extend has been a long-standing question 1 , 2 . Resolving this puzzle has been a primary goal for the Juno spacecraft 3 , 4 , which has been in orbit around the gas giant since July 2016. Juno’s gravitational measurements have revealed that Jupiter’s gravitational field is north–south asymmetric 5 , which is a signature of the planet’s atmospheric and interior flows 6 . Here we report that the measured odd gravitational harmonics J 3 , J 5 , J 7 and J 9 indicate that the observed jet streams, as they appear at the cloud level, extend down to depths of thousands of kilometres beneath the cloud level, probably to the region of magnetic dissipation at a depth of about 3,000 kilometres 7 , 8 . By inverting the measured gravity values into a wind field 9 , we calculate the most likely vertical profile of the deep atmospheric and interior flow, and the latitudinal dependence of its depth. Furthermore, the even gravity harmonics J 8 and J 10 resulting from this flow profile also match the measurements, when taking into account the contribution of the interior structure 10 . These results indicate that the mass of the dynamical atmosphere is about one per cent of Jupiter’s total mass.

Titanium oxide, water, sodium and a strongly scattering haze have been detected in the atmosphere of the hot Jupiter exoplanet WASP-19b. Titanium oxide in the atmosphere of a hot Jupiter The atmospheres of some hot Jupiters contain compounds of light and cosmically abundant elements. Metal oxides such as titanium oxide and vanadium oxide have been predicted to also be present, but hitherto have not been observed. Using high-precision spectroscopy, Elyar Sedaghati et al . have now detected titanium oxide in the atmosphere of the hot Jupiter WASP-19b. The researchers have also seen evidence of water and a strongly scattering haze. The findings pave the way for future studies of heavy elements in these hot exoplanetary atmospheres. As an exoplanet transits its host star, some of the light from the star is absorbed by the atoms and molecules in the planet’s atmosphere, causing the planet to seem bigger; plotting the planet’s observed size as a function of the wavelength of the light produces a transmission spectrum 1 . Measuring the tiny variations in the transmission spectrum, together with atmospheric modelling, then gives clues to the properties of the exoplanet’s atmosphere. Chemical species composed of light elements—such as hydrogen, oxygen, carbon, sodium and potassium—have in this way been detected in the atmospheres of several hot giant exoplanets 2 , 3 , 4 , 5 , but molecules composed of heavier elements have thus far proved elusive. Nonetheless, it has been predicted that metal oxides such as titanium oxide (TiO) and vanadium oxide occur in the observable regions of the very hottest exoplanetary atmospheres, causing thermal inversions on the dayside 6 , 7 . Here we report the detection of TiO in the atmosphere of the hot-Jupiter planet WASP-19b. Our combined spectrum, with its wide spectral coverage, reveals the presence of TiO (to a confidence level of 7.7 σ ), a strongly scattering haze (7.4 σ ) and sodium (3.4 σ ), and confirms the presence of water (7.9 σ ) in the atmosphere 5 , 8 .

Visible and infrared images obtained from above each pole of Jupiter by the Juno spacecraft reveal polygonal patterns of large cyclones; it is unknown how these cyclones evolved, or how they persist without merging. Polygonal cyclones around Jupiter's poles Jupiter's colourful low-latitude weather bands turn into cyclones at high latitudes, but the polar region is not visible from Earth and was poorly characterized by previous spacecraft. Alberto Adriani and colleagues report visible and infrared observations of Jupiter's polar regions made by the Juno spacecraft, which is in a highly elliptical polar orbit. They find that the cyclones create persistent polygonal patterns. There are eight circumpolar cyclones rotating around a single cyclone in the north, while the South Polar Cyclone is circled by five such features. The authors do not know how these cyclones evolved to their current state or how they persist without merging. The familiar axisymmetric zones and belts that characterize Jupiter’s weather system at lower latitudes give way to pervasive cyclonic activity at higher latitudes 1 . Two-dimensional turbulence in combination with the Coriolis β-effect (that is, the large meridionally varying Coriolis force on the giant planets of the Solar System) produces alternating zonal flows 2 . The zonal flows weaken with rising latitude so that a transition between equatorial jets and polar turbulence on Jupiter can occur 3 , 4 . Simulations with shallow-water models of giant planets support this transition by producing both alternating flows near the equator and circumpolar cyclones near the poles 5 , 6 , 7 , 8 , 9 . Jovian polar regions are not visible from Earth owing to Jupiter’s low axial tilt, and were poorly characterized by previous missions because the trajectories of these missions did not venture far from Jupiter’s equatorial plane. Here we report that visible and infrared images obtained from above each pole by the Juno spacecraft during its first five orbits reveal persistent polygonal patterns of large cyclones. In the north, eight circumpolar cyclones are observed about a single polar cyclone; in the south, one polar cyclone is encircled by five circumpolar cyclones. Cyclonic circulation is established via time-lapse imagery obtained over intervals ranging from 20 minutes to 4 hours. Although migration of cyclones towards the pole might be expected as a consequence of the Coriolis β-effect, by which cyclonic vortices naturally drift towards the rotational pole, the configuration of the cyclones is without precedent on other planets (including Saturn’s polar hexagonal features). The manner in which the cyclones persist without merging and the process by which they evolve to their current configuration are unknown.

The MAJIS (Moons And Jupiter Imaging Spectrometer) instrument on board the ESA JUICE (JUpiter ICy moon Explorer) mission is an imaging spectrometer operating in the visible and near-infrared spectral range from 0.50 to 5.55 μm in two spectral channels with a boundary at 2.3 μm and spectral samplings for the VISNIR and IR channels better than 4 nm/band and 7 nm/band, respectively. The IFOV is 150 μrad over a total of 400 pixels. As already amply demonstrated by the past and present operative planetary space missions, an imaging spectrometer of this type can span a wide range of scientific objectives, from the surface through the atmosphere and exosphere. MAJIS is then perfectly suitable for a comprehensive study of the icy satellites, with particular emphasis on Ganymede, the Jupiter atmosphere, including its aurorae and the spectral characterization of the whole Jupiter system, including the ring system, small inner moons, and targets of opportunity whenever feasible. The accurate measurement of radiance from the different targets, in some case particularly faint due to strong absorption features, requires a very sensitive cryogenic instrument operating in a severe radiation environment. In this respect MAJIS is the state-of-the-art imaging spectrometer devoted to these objectives in the outer Solar System and its passive cooling system without cryocoolers makes it potentially robust for a long-life mission as JUICE is. In this paper we report the scientific objectives, discuss the design of the instrument including its complex on-board pipeline, highlight the achieved performance, and address the observation plan with the relevant instrument modes.

This article deals with the prediction of the upcoming solar activity cycle, Solar Cycle 25. We propose that astronomical ephemeris, specifically taken from the catalogs of aphelia of the four Jovian planets, could be drivers of variations in solar activity, represented by the series of sunspot numbers (SSN) from 1749 to 2020. We use singular spectrum analysis (SSA) to associate components with similar periods in the ephemeris and SSN. We determine the transfer function between the two data sets. We improve the match in successive steps: first with Jupiter only, then with the four Jovian planets and finally including commensurable periods of pairs and pairs of pairs of the Jovian planets (following Mörth and Schlamminger in Planetary Motion, Sunspots and Climate, Solar-Terrestrial Influences on Weather and Climate , 193, 1979 ). The transfer function can be applied to the ephemeris to predict future cycles. We test this with success using the “hindcast prediction” of Solar Cycles 21 to 24, using only data preceding these cycles, and by analyzing separately two 130 and 140 year-long halves of the original series. We conclude with a prediction of Solar Cycle 25 that can be compared to a dozen predictions by other authors: the maximum would occur in 2026.2 (± 1 yr) and reach an amplitude of 97.6 (± 7.8), similar to that of Solar Cycle 24, therefore sketching a new “Modern minimum”, following the Dalton and Gleissberg minima.

The interior oceans of several icy moons are considered as affected by rotation. Observations suggest a larger heat transport around the poles than at the equator. Rotating Rayleigh‐Bénard convection (RRBC) in planar configuration can show an enhanced heat transport compared to the non‐rotating case within this “rotation‐affected” regime. We investigate the potential for such a (polar) heat transport enhancement in these subglacial oceans by direct numerical simulations of RRBC in spherical geometry for Ra = 106 and 0.7 ≤ Pr ≤ 4.38. We find an enhancement up to 28% in the “polar tangent cylinder,” which is globally compensated by a reduced heat transport at low latitudes. As a result, the polar heat transport can exceed the equatorial by up to 50%. The enhancement is mostly insensitive to different radial gravity profiles, but decreases for thinner shells. In general, polar heat transport and its enhancement in spherical RRBC follow the same principles as in planar RRBC. Plain Language Summary The icy moons of Jupiter and Saturn like for example, Europa, Titan, or Enceladus are believed to have a water ocean beneath their ice crust. Several of them show phenomena in their polar regions like active geysers or a thinner crust than at the equator, all of which might be related to a larger heat transport around the poles from the underlying ocean. We simulate the flow dynamics and currents in these subglacial ocean by high‐fidelity simulations, though still at less extreme parameters than in reality, to study the heat transport and provide a possible explanation of such a “polar heat transport enhancement.” We find that the heat transport around the poles can be up to 50% larger than around the equator, and that the believed properties of the icy moons and their oceans would allow polar heat transport enhancement. Therefore, our results may help to improve the understanding of ocean currents and latitudinal variations in the oceanic heat transport and crustal thickness on icy moons. Key Points The polar heat transport in spherical rotating Rayleigh‐Bénard convection experiences an enhancement by rotation The influence of rotation differs at low latitudes: the heat flux is reduced and compensates the polar enhancement on the global average In combination, this strengthens the latitudinal variation between polar and equatorial heat flux for Prandtl numbers larger than unity

The Cassini Imaging Science Subsystem acquired about 26,000 images of the Jupiter system as the spacecraft encountered the giant planet en route to Saturn. We report findings on Jupiter's zonal winds, convective storms, low-latitude upper troposphere, polar stratosphere, and northern aurora. We also describe previously unseen emissions arising from Io and Europa in eclipse, a giant volcanic plume over Io's north pole, disk-resolved images of the satellite Himalia, circumstantial evidence for a causal relation between the satellites Metis and Adrastea and the main jovian ring, and information on the nature of the ring particles.

Observations from the Juno spacecraft near the M‐shells of the Galilean moons have identified alternating enhancements and reductions of particle fluxes at discrete energies. These banded structures were previously attributed to bounce resonance between particles and standing Alfvén waves generated by moon‐magnetospheric interactions. Here, we show that this explanation is inconsistent with key observational features, and propose an alternative interpretation: the bands are remote signatures of particle absorption at the moons. In this scenario, whether a particle encounters the moon before reaching Juno depends on the number of bounce cycles it undergoes within a fixed drift segment determined by the moon‐spacecraft separation. Therefore, the absorption bands are expected to appear at discrete, equally‐spaced velocities. This is largely consistent with the observations, though discrepancies remain, possibly due to spacecraft charging and/or finite data resolution. This finding improves our understanding of moon‐plasma interactions and may help constrain Jovian magnetospheric models.