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Abstract: The contrasting internal luminosity of Uranus and Neptune present a challenge to our understanding of the origin and evolution of these bodies, as well as extra-solar ice giants. The thermal evolution of Neptune is known to be nearly consistent with an entirely fluid interior, but this is not a unique solution, and does not account for the tidal dissipation required by the migration of its moons. We examine a model that has been previously shown to explain the thermal and tidal evolution of Uranus: one that features a growing, frozen core. The core traps heat in the interior, affecting the cooling time scale, and provides a source of tidal dissipation. We review the growing, frozen core model, and the computation of thermal and tidal evolution. We then apply this model to Neptune. We find that the growing frozen core model can account for the observed internal luminosity of Neptune and the migration of its moons, in the form of resonances that were either encountered or avoided in the past. We discuss prospects for observational tests of the growing frozen core model and possible implications for understanding the gas giants.

Recent observations of Jupiter's atmosphere showing unexpected depletion of ammonia below the ammonia cloud-forming region has brought up the question of whether a single point measurement below the cloud decks in a giant planet atmosphere can provide sufficient information to answer fundamental science questions. We outline here the science questions that can only be answered by in situ observations in the giant planet atmospheres, many of which are location invariant. These questions are identified in the recent planetary science decadal survey as high priority for answering over the next decade. We evaluate the implications of the ammonia observations at Jupiter for the specific measurements needed and demonstrate that they do not invalidate single point measurements made to answer these questions. [ABSTRACT FROM AUTHOR]

A team of Earth-based astronomical observers supporting a giant planet entry-probe event substantially enhances the scientific return of the mission. An observers’ team provides spatial and temporal context, additional spectral coverage and resolution, viewing geometries that are not available from the probe or the main spacecraft, tracking, supporting data in case of a failure, calibration benchmarks, and additional opportunities for education and outreach. The capabilities of the support program can be extended by utilizing archived data. The existence of a standing group of observers facilitates the path towards acquiring Director’s Discretionary Time at major telescopes, if, for example, the probe’s entry date moves. The benefits of a team convened for a probe release provides enhanced scientific return throughout the mission. Finally, the types of observations and the organization of the teams described in this paper could serve as a model for flight projects in general. [ABSTRACT FROM AUTHOR]

The magnetospheric systems of ice giants, as the ideal and the unique template of a typical class of exoplanets, have not been sufficiently studied in the past decade. The complexity of these asymmetric and extremely dynamic magnetospheres provides us a great chance to systematically investigate the general mechanism of driving the magnetospheres of such common exoplanets in the Universe, and the key factors of influencing the global and local magnetospheric structures of this type of planets. In this paper, we discuss the science return of probing magnetospheric systems of ice giants for the future missions, throughout different magnetospheric regions, across from the interaction with upstream solar wind to the downstream region of the magnetotail. We emphasize the importance of detecting the magnetospheric systems of ice giants in the next decades, which enables us to deeply understand the space enviroNMent and habitability of not only the ice giants themselves but also the analogous exoplanets which are widely distributed in the Universe. [ABSTRACT FROM AUTHOR]

Deep elemental composition is a challenging measurement to achieve in the giant planets of the solar system. Yet, knowledge of the deep composition offers important insights in the internal structure of these planets, their evolutionary history and their formation scenarios. A key element whose deep abundance is difficult to obtain is oxygen, because of its propensity for being in condensed phases such as rocks and ices. In the atmospheres of the giant planets, oxygen is largely stored in water molecules that condense below the observable levels. At atmospheric levels that can be investigated with remote sensing, water abundance can modify the observed meteorology, and meteorological phenomena can distribute water through the atmosphere in complex ways that are not well understood and that encompass deeper portions of the atmosphere. The deep oxygen abundance provides constraints on the connection between atmosphere and interior and on the processes by which other elements were trapped, making its determination an important element to understand giant planets. In this paper, we review the current constraints on the deep oxygen abundance of the giant planets, as derived from observations and thermochemical models. [ABSTRACT FROM AUTHOR]

In this paper, the improved design of an Ice Giants Net Flux Radiometer (IG-NFR), for inclusion as a payload on a future Uranus probe mission, is given. IG-NFR will measure the net radiation flux, in seven spectral bands, each with a 10° Field-Of-View (FOV) and in five viewing angles as a function of altitude. Net flux measurements within spectral filter bands, ranging from solar to far-infrared, will help derive radiative heating and cooling profiles, and will significantly contribute to our understanding of the planet's atmospheric heat balance and structure, tropospheric 3-D flow, and compositions and opacities of the cloud layers. The IG-NFR uses an array of non-imaging Winston cones integrated to a matched thermopile detector Focal Plane Assembly (FPA), with individual bandpass filters and windows, housed in a vacuum micro-vessel. The FPA thermopile detector signals are read out in parallel mode, amplified and processed by a multi-channel digitizer application specific integrated circuit (MCD ASIC) under field programmable gate array (FPGA) control. The vacuum micro-vessel rotates providing chopping between FOV's of upward and downward radiation fluxes. This unique design allows for small net flux measurements in the presence of large ambient fluxes and rapidly changing temperatures during the probe descent to ≥10 bar pressure. [ABSTRACT FROM AUTHOR]

Though enjoying complete intellectual and financial independence during the first half century of its existence, Lowell Observatory was forced to change its model after World War II, as science itself increasingly morphed into 'Big Science'. The first major source of outside funding in the Observatory's history was the US Weather Bureau, which supported a project to understand weather on a planetary scale by studying weather on Mars and Jupiter and--more enduringly--to record possible variations of solar irradiance. The latter was a longstanding problem which had occupied scientists such as Charles Greeley Abbot at the Smithsonian Astrophysical Observatory for decades, and had so far led to inconclusive results. At Lowell, it was to be approached by an innovative, if indirect, method involving the monitoring of changes of brightness in sunlight reflected from the cloudy atmospheres of distant Uranus and Neptune--a method whose time had just come, as photoelectric photometry had only just developed to the point where its implementation was feasible. Even so, it required a very high level of specialized knowledge and skill to be successful, and the Observatory was fortunate in recruiting young Harold L. Johnson, who was the best person possible for the job, to devise the instrumentation and design as well as provide overall supervision to the project from its inception until 1959 when he left Lowell. After his departure, the project, employing his experimental design, continued under the directorship of John S. Hall, mainly through the efforts of two Polish astronomers, K. Serkowski and M. Jerzykiewicz, who in 1966 concluded that, though the measures of Uranus could not be relied on owing to its uncertain oblateness, the detected variations of brightness of Neptune might be real, and if so, could be due either to changes in Neptune's atmosphere or to variations of the Sun. Air Force funding ran out in 1966. However, through the advocacy of climatologist J. Murray Mitchell Jr, the project was revived in 1971, with Saturn's large satellite Titan as an additional target. Jerzykiewicz returned to Lowell for two years before going back to Poland, whereupon he turned the project over in 1973 to G. Wesley Lockwood. The latter continued the observations of Uranus, Neptune and Titan until 2016, logging in addition atmospheric extinction data through two global volcanic episodes, El Chich'n and Pinatubo. With the advent of the solar satellite era after 1980, when more direct methods of determining solar irradiance became available, the planetary observations increasingly adopted as their new goal the monitoring of planetary seasonal variability. An on-again, off-again anti-correlation of Neptune's brightness with the sunspot number was suspected at Lowell but not finally and definitively established as a Sun-Neptune planetary weather effect until Berkeley scientists did so in 2023. However, probably the most important discovery made during the long-running Lowell programme was a serendipitous one. From the monitoring of solar-type stars originally included as standards of comparison for the planetary brightness measures, it was found that the brightness of some of these stars varied considerably more than the Sun does. Thus, as a byproduct of the Lowell project, a new vigorous area of ongoing research was established that continues to the present day. [ABSTRACT FROM AUTHOR]

The magnetospheric systems of ice giants, as the ideal and the unique template of a typical class of exoplanets, have not been sufficiently studied in the past decade. The complexity of these asymmetric and extremely dynamic magnetospheres provides us a great chance to systematically investigate the general mechanism of driving the magnetospheres of such common exoplanets in the Universe, and the key factors of influencing the global and local magnetospheric structures of this type of planets. In this paper, we discuss the science return of probing magnetospheric systems of ice giants for the future missions, throughout different magnetospheric regions, across from the interaction with upstream solar wind to the downstream region of the magnetotail. We emphasize the importance of detecting the magnetospheric systems of ice giants in the next decades, which enables us to deeply understand the space enviroNMent and habitability of not only the ice giants themselves but also the analogous exoplanets which are widely distributed in the Universe.

Uranus and Neptune form a distinct class of planets in our Solar System. Given this fact, and ubiquity of similar-mass planets in other planetary systems, it is essential to understand their interior structure and composition. However, there are more open questions regarding these planets than answers. In this review, we concentrate on the things we do not know about the interiors of Uranus and Neptune with a focus on why the planets may be different, rather than the same. We next summarize the knowledge about the planets' internal structure and evolution. Finally, we identify the topics that should be investigated further on the theoretical front as well as required observations from space missions. This article is part of a discussion meeting issue 'Future exploration of ice giant systems'.

A dedication to Neptune discovered in 1963 at Feriana, the ancient Thelepte in Africa Proconsularis, has long remained on the sidelines of studies on ancient Africa. Briefly reported and published several times, this very short text is the only document of this type from this very important but very little excavated site. It also attests a very rare name, Magaricus, which until then was only attested in Sicca Veneria in the form Macaricus, close to the ethnonym Mager / Magar precisely attested in this region of Tunisia since Antiquity.

Turbulence in the outer planetary magnetospheres has been relatively less studied than in the Earth's magnetosphere, especially for the ice giants which have been visited only by the Voyager-2 spacecraft so far. The aim of this work is to study the turbulence in Neptune's dayside magnetosheath. Voyager-2 magnetometer 3-s averaged magnetic field data were analyzed with several data analysis techniques. It was found that most of the magnetosheath magnetic field is aligned in the B T direction. The B R -component spectrum showed the predominance of short-period (5 minutes) oscillations, while the B T - and B N - components showed the occurrence of longer-period (20 – 50 minutes) oscillations. The Fourier spectrum of the magnetic field showed a breakpoint near 0.00165 Hz. The lower frequency portion showed index (absolute values) smaller than 1.0. The higher frequency portion showed a much steeper spectrum, with power law values varying from about 2.0 to 2.4. The statistical kurtosis parameters for B R and B N are higher than 3 in almost all scales, while the B T component (main field direction) has a more Gaussian or sub-Gaussian behavior, specially in scales higher than 20 minutes. The kurtosis is very high at the low frequency spectral power of 40 minutes for the B N -component, indicating asymmetric or non-Gaussian magnetic field distribution in the magnetosheath. The multifractal spectrum is well spread in the magnetosheath revealing a rich and dynamic activity in this region. Overall, the Neptune's magnetosheath is found to have a strong turbulence activity that is comparable to that of other planetary magnetosheaths. [ABSTRACT FROM AUTHOR]

[Display omitted] • CFD/radiative transfer simulations carried out for a Neptune 18 km/s entry or 29 km/s aerocapture. • Traces of Methane in Neptune's atmosphere significantly enhance wall radiative heating. • 45° sphere-cone shapes ensure better aerodynamic stability for such flight conditions. An aerothermodynamic analysis of representative aerocapture (29 km/s) and entry (18 km/s) flows in Neptune is discussed. Two 60° and 45° sphere-cone shapes are considered, and chemically-reactive, nonequilibrium flowfield solutions are computed for the forebody region, yielding surface heat fluxes from convective heating. A radiative transfer calculation using a line-by-line approach coupled with a ray-tracing routine, yields surface heat fluxes from radiative heating. If the trace amounts of CH 4 in Neptune's atmosphere are accounted for, they dramatically enchance radiative heating, as a result of strong radiative emission from carbonaceous species in the shock layer. For the 18 km/s entry point, radiative heat fluxes accordingly increase by several orders of magnitude, from 0% to about 50% of the total heat fluxes. The post-shock flow features further differ significantly depending on the capsule shape. The sonic line is near the sphere-cone transition zone for the 45° shape and starts detaching from the boundary layer for angles above 55°. The post-shock flow becomes entirely subsonic up to the spacecraft shoulder at 60°. More streamlined shapes will accordingly be more aerodynamically stable. [ABSTRACT FROM AUTHOR]

• We report prespecified exploratory analyses of an mNSCLC cohort in China (NEPTUNE). 85 chars. • First-line durvalumab + tremelimumab showed a trend of improved OS vs chemotherapy. 85 chars. • This trend was observed in all patients and those with low tumor PD-L1 expression. 84 chars. • 24-month OS and 12-month PFS rates indicated benefit in the survival curve tails. 83 chars. • Durvalumab + tremelimumab was well tolerated with no new safety signals. 74 chars. The phase 3 NEPTUNE study (NCT02542293) evaluated first-line durvalumab plus tremelimumab (DT) versus chemotherapy for metastatic NSCLC. Prespecified exploratory analyses were conducted in an extended cohort enrolled in China. Patients were randomized (1:1) to DT or standard chemotherapy, stratified by PD-L1 tumor cell (TC) expression (≥25 % vs < 25 %), histology, and smoking history. The primary analysis for this cohort was overall survival (OS) in patients with PD-L1 TC < 1 %. Secondary analyses included OS and progression-free survival (PFS) in the ITT population and PD-L1 subgroups, and safety. No alpha was allocated to these cohort analyses (data cut-off, 21-September-2020). 78 and 82 patients were randomized to DT and chemotherapy, respectively; 26 and 29 had PD-L1 TC < 1 % (median follow-up, 31.2 and 29.7 months [censored patients]). Among patients with PD-L1 TC < 1 %, OS favored DT versus chemotherapy (HR 0.60; 95 % CI, 0.32–1.11), with medians of 15.0 months (95 % CI, 10.5–27.4) and 11.7 months (95 % CI, 8.6–20.5), respectively; 24-month rates were 36.0 % (95 % CI, 18.2–54.2) and 17.9 % (95 % CI, 6.5–33.7). In the ITT population, OS was prolonged with DT versus chemotherapy (HR 0.70; 95 % CI, 0.48–1.02); medians were 20.0 and 14.1 months and 24-month rates were 44.2 % and 30.4 %. PFS was similar in the PD-L1 TC < 1 % (HR 1.13; 95 % CI, 0.59–2.14) and ITT (HR 0.95; 95 % CI, 0.66–1.36) populations; 12-month rates were 15.6 % versus 11.3 % and 23.9 % versus 16.6 %. Grade 3/4 treatment-related adverse events (TRAEs) occurred in 31.2 % with DT and 52.6 % with chemotherapy; 3.9 % versus 10.3 % discontinued due to TRAEs. In exploratory analyses, first-line DT showed a trend towards improved OS versus chemotherapy among Chinese patients in the PD-L1 TC < 1 % population and ITT population, with 24-month OS and 12-month PFS rates indicating benefit in survival curve tails. DT was well tolerated with no new safety signals. [ABSTRACT FROM AUTHOR]

Radio observations of the atmospheres of the giant planets Jupiter, Saturn, Uranus, and Neptune have provided invaluable constraints on atmospheric dynamics, physics/chemistry, and planet formation theories over the past 70 years. We provide a brief history of these observations, with a focus on recent and state-of-the-art studies. The global circulation patterns, as derived from these data, in combination with observations at UV/visible/near-IR wavelengths and in the thermal infrared, suggest a vertically-stacked pattern of circulation cells in the troposphere, with the top cell similar to the classical picture, overlying cells with the opposite circulation. Data on the planets' bulk compositions are used to support or disfavor different planet formation scenarios. While heavy element enrichment in the planets favors the core accretion model, we discuss how the observed relative enrichments in volatile species constrain models of the outer proto-planetary disk and ice giant accretion. Radio observations of planets will remain invaluable in the next decades, and we close with some comments on the scientific gain promised by proposed and under-construction radio telescopes. [ABSTRACT FROM AUTHOR]

Flyby tours are challenging to design due to the extraordinarily large search space. A single algorithm is proposed to answer the question of what low-cost, post-flyby options exist for a spacecraft arriving at a flyby body. The algorithm a) considers the full domain of reachable bodies and transfer types including even- and odd-nπ resonant ballistic, nonresonant ballistic, and v -infinity leveraging; b) identifies families of solutions instead of just single points; and c) structures the search to only seek solutions within a Δv threshold. This algorithm extends and integrates these state-of-the-art characteristics, and is designed to rapidly inform an outer-loop pathfinding scheme for flyby tour design. Detailed examples of resulting solutions and families are provided for multiple variations of three different use case scenarios, including tours in the Jupiter, Saturn, and sun systems. As a representative example in the Jupiter system starting at Callisto, the algorithm takes on the order of 0.1 s to find over 500 solutions with Δv costs below 200  m/s organized into nearly 70 families, all either returning to Callisto or proceeding to Ganymede. [ABSTRACT FROM AUTHOR]

This study, placed in the context of the preparation for the Uranus Orbiter Probe mission, aims to predict the bulk volatile compositions of Uranus and Neptune. Using a protoplanetary disk model, it examines the evolution of trace species through vapor and solid transport as dust and pebbles. Due to the high carbon abundance found in their envelopes, the two planets are postulated to have formed at the carbon monoxide ice line within the protosolar nebula. The time evolution of the abundances of the major volatile species at the location of the CO ice line is then calculated to derive the abundance ratios of the corresponding key elements, including the heavy noble gases, in the feeding zones of Uranus and Neptune. Supersolar metallicity in their envelopes likely results from accreting solids in these zones. Two types of solids are considered: pure condensates (Case 1) and a mixture of pure condensates and clathrates (Case 2). The model, calibrated to observed carbon enrichments, predicts deep compositions. In Case 1, argon is deeply depleted, while nitrogen, oxygen, krypton, phosphorus, sulfur, and xenon are significantly enriched relative to their protosolar abundances in the two planets. Case 2 predicts significant enrichments for all species, including argon, relative to their protosolar abundances. Consequently, Case 1 predicts near-zero Ar/Kr or Ar/Xe ratios, while Case 2 suggests that these ratios are 0.1 and 0.5–1 times their protosolar ratios, respectively. Both cases predict a bulk sulfur-to-nitrogen ratio consistent with atmospheric measurements.

In the Nice model of Solar System formation, Uranus and Neptune undergo an orbital upheaval, sweeping through a planetesimal disk. The region of the disk from which material is accreted by the ice giants during this phase of their evolution has not previously been identified. We perform direct N -body orbital simulations of the four giant planets to determine the amount and origin of solid accretion during this orbital upheaval. We find that the ice giants undergo an extreme bombardment event, with collision rates as high as ∼3 per hour assuming km-sized planetesimals, increasing the total planet mass by up to ∼0.35%. In all cases, the initially outermost ice giant experiences the largest total enhancement. We determine that, for some plausible planetesimal properties, the resulting atmospheric enrichment could potentially produce sufficient latent heat to alter the planetary cooling timescale according to existing models. Our findings suggest that substantial accretion during this phase of planetary evolution may have been sufficient to impact the atmospheric composition and thermal evolution of the ice giants, motivating future work on the fate of deposited solid material.

Storms operated by moist convection and the condensation of CH _4 or H _2 S have been observed on Uranus and Neptune. However, the mechanism of cloud formation, thermal structure, and mixing efficiency of ice giant weather layers remains unclear. In this paper, we show that moist convection is limited by heat transport on giant planets, especially on ice giants where planetary heat flux is weak. Latent heat associated with condensation and evaporation can efficiently bring heat across the weather layer through precipitations. This effect was usually neglected in previous studies without a complete hydrological cycle. We first derive analytical theories and show that the upper limit of cloud density is determined by the planetary heat flux and microphysics of clouds but is independent of the atmospheric composition. The eddy diffusivity of moisture depends on the planetary heat fluxes, atmospheric composition, and surface gravity but is not directly related to cloud microphysics. We then conduct convection- and cloud-resolving simulations with SNAP to validate our analytical theory. The simulated cloud density and eddy diffusivity are smaller than the results acquired from the equilibrium cloud condensation model and mixing length theory by several orders of magnitude but consistent with our analytical solutions. Meanwhile, the mass-loading effect of CH _4 and H _2 S leads to superadiabatic and stable weather layers. Our simulations produced three cloud layers that are qualitatively similar to recent observations. This study has important implications for cloud formation and eddy mixing in giant planet atmospheres in general and observations for future space missions and ground-based telescopes.

While there have been far fewer missions to the outer Solar System than to the inner Solar System, spacecraft destined for the giant planets have conducted a wide range of fundamental investigations, returning data that continues to reshape our understanding of these complex systems, sometimes decades after the data were acquired. These data are preserved and accessible from national and international planetary science archives. For all NASA planetary missions and instruments the data are available from the science discipline nodes of the NASA Planetary Data System (PDS). Looking ahead, the PDS will be the primary repository for giant planets data from several upcoming missions and derived datasets, as well as supporting research conducted to aid in the interpretation of the remotely sensed giant planets data already archived in the PDS. [ABSTRACT FROM AUTHOR]

Of all the myriad environments in our Solar System, the least explored are the distant Ice Giants Uranus and Neptune, and their diverse satellite and ring systems. These 'intermediate-sized' worlds are the last remaining class of Solar System planet to be characterised by a dedicated robotic mission, and may shape the paradigm for the most common outcome of planetary formation throughout our galaxy. In response to the 2019 European Space Agency call for scientific themes in the 2030s and 2040s (known as Voyage 2050), we advocated that an international partnership mission to explore an Ice Giant should be a cornerstone of ESA's science planning in the coming decade, targeting launch opportunities in the early 2030s. This article summarises the inter-disciplinary science opportunities presented in that White Paper [1], and briefly describes developments since 2019. [ABSTRACT FROM AUTHOR]

Uranus and Neptune are commonly considered ice giants, and it is often assumed that, in addition to a solar mix of hydrogen and helium, they contain roughly twice as much water as rock. This classical picture has led to successful models of their internal structure and has been understood to be compatible with the composition of the solar nebula during their formation (Reynolds and Summers, 1965; Podolak and Cameron, 1974; Podolak and Reynolds, 1984; Podolak et al., 1995). However, the dominance of water has been recently questioned (Teanby et al., 2020; Helled and Fortney, 2020; Podolak et al., 2022). Planetesimals in the outer solar system are composed mainly of refractory materials, leading to an inconsistency between the icy composition of Uranus and Neptune and the ice-poor planetesimals they accreted during formation (Podolak et al., 2022). Here we elaborate on this problem, and propose a new potential solution. We show that chemical reactions between planetesimals dominated by organic-rich refractory materials and the hydrogen in gaseous atmospheres of protoplanets can form large amounts of methane 'ice'. Uranus and Neptune could thus be compatible with having accreted refractory-dominated planetesimals, while still remaining icy. Using random statistical computer models for a wide parameter space, we show that the resulting methane-rich internal composition could be a natural solution, giving a good match to the size, mass and moment of inertia of Uranus and Neptune, whereas rock-rich models appear to only work if a rocky interior is heavily mixed with hydrogen. Our model predicts a lower than solar hydrogen to helium ratio, which can be tested. We conclude that Uranus, Neptune and similar exoplanets could be methane-rich, and discuss why Jupiter and Saturn cannot. • The ice giants Uranus and Neptune are typically considered to be water-rich. • Outer Solar system solids are refractory-rich, raising a composition tension problem. • Random interior models of the outer planets pose a severe limit for the rock fraction. • Instead, we show that chemistry can transform carbon-rich refractories into methane. • If Uranus and Neptune are methane-rich, we predict a large helium to hydrogen ratio. [ABSTRACT FROM AUTHOR]

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Along the ancient via Ostiense (about 1,2 km south of the 10th mile), near Castel Porziano pine forest, there are the remains of large Roman villa dating between the 1st century BC and late 3th century AD. There is no information on excavations in this site, probably carried out before 1923. Some rooms were richly decorated, for example those belonging to the balneum of the building complex; moreover, traces of an oil press (torcular) were also found in the pars rustica of the villa. In the main hall there is a figural black and white mosaic (m 6,75 × 6,55), where Neptune, Nereids and sea creatures are depicted; a similar marine thiasos appears in the well-known mosaic of the Baths of Buticosus in Ostia Antica. During 1947, the monumental mosaic of Risaro, dated to the Hadrianic-Antonine period, was taken to room V in the Museo Nazionale Romano (Terme di Diocleziano). [ABSTRACT FROM AUTHOR]

We present a reanalysis (using the Minnaert limb‐darkening approximation) of visible/near‐infrared (0.3–2.5 μm) observations of Uranus and Neptune made by several instruments. We find a common model of the vertical aerosol distribution i.e., consistent with the observed reflectivity spectra of both planets, consisting of: (a) a deep aerosol layer with a base pressure >5–7 bar, assumed to be composed of a mixture of H2S ice and photochemical haze; (b) a layer of photochemical haze/ice, coincident with a layer of high static stability at the methane condensation level at 1–2 bar; and (c) an extended layer of photochemical haze, likely mostly of the same composition as the 1–2‐bar layer, extending from this level up through to the stratosphere, where the photochemical haze particles are thought to be produced. For Neptune, we find that we also need to add a thin layer of micron‐sized methane ice particles at ∼0.2 bar to explain the enhanced reflection at longer methane‐absorbing wavelengths. We suggest that methane condensing onto the haze particles at the base of the 1–2‐bar aerosol layer forms ice/haze particles that grow very quickly to large size and immediately "snow out" (as predicted by Carlson et al. (1988), https://doi.org/10.1175/1520-0469(1988)045<2066:CMOTGP>2.0.CO;2), re‐evaporating at deeper levels to release their core haze particles to act as condensation nuclei for H2S ice formation. In addition, we find that the spectral characteristics of "dark spots", such as the Voyager‐2/ISS Great Dark Spot and the HST/WFC3 NDS‐2018, are well modelled by a darkening or possibly clearing of the deep aerosol layer only. Plain Language Summary: Previous studies of the reflectance spectra of Uranus and Neptune have concentrated on individual, narrow wavelength regions and the conclusions have been difficult to compare with each other. Here, we analyse a combined set of observations from three different instruments covering the wavelength range 0.3–2.5 μm to arrive at a single aerosol model that matches the observations at all wavelengths simultaneously for both planets. We conclude that photochemical haze produced in the upper atmospheres of both planets is steadily mixed down to lower layers, where it forms part of a vertically thin layer in a statically stable region above the methane condensation level at 1–2 bar. We suggest that methane condenses so rapidly upon these haze particles that it efficiently "snows" out at the base of this layer, falling to lower, warmer levels, where the methane evaporates, releasing the core haze particles to "seed" H2S condensation. For Neptune we need to add an additional layer of moderately large methane ice particles at ∼0.2 bar. Intriguingly, we find that a darkening (or perhaps clearing) of the lowest H2S/haze layer matches very well the observed properties of the dark spots seen occasionally in Neptune's atmosphere and very occasionally in Uranus's atmosphere. Key Points: Ice Giant reflectivity spectra from 0.3 to 2.5 μm well approximated by a single aerosol model comprised of three to four distinct layersStatic stability region at 1–2 bar, caused by methane condensation, seems to lead to build‐up of haze and seeds CH4 snow at its baseDarkening of deepest H2S/haze layer, based at p > 5–7 bar, found to account well for spectral properties of dark spots [ABSTRACT FROM AUTHOR]

In this work, a comparison of potential flight control methodologies for Neptune aerocapture trajectories is presented. Lifting trajectories pertaining to bank angle modulation and direct force control as well as ballistic trajectories pertaining to continuously-variable drag modulation are investigated. A parametric study of vehicle configurations is explored to quantitatively compare the flight envelope between lifting and ballistic trajectories. A closed-loop numerical predictor–corrector aerocapture guidance architecture is utilized to unify each flight control technique for trajectory comparisons. A series of Monte Carlo simulations of blunt body Neptune aerocapture trajectories are conducted to assess each flight control's robustness to uncertainties in vehicle aerodynamics, atmospheric knowledge, and entry state. Direct force control can achieve 100% successful science orbit insertion within a 120 m/s total Δ V budget. Bank angle modulation can achieve 100% successful science orbit insertion within a 300 m/s total Δ V budget. Continuously-variable drag modulation can achieve 99.3% successful science orbit insertion within a 190 m/s total Δ V budget but at 3 times lower peak stagnation point convective heating rate. • Qualitative comparison between lifting and ballistic aerocapture trajectories. • Modular aerocapture guidance architecture developed for quantitative simulations. • Direct force control, bank angle modulation, and drag modulation flight controls. • For Neptune, direct force control provides best orbit insertion. • For Neptune, drag modulation can reduce aerodynamic heating by a factor of 3. [ABSTRACT FROM AUTHOR]

The strikingly low luminosity of Uranus (Teff ~ Teq) constitutes along-standing challenge to our understanding of Ice Giant planets. Here wepresent the first Uranus structure and evolution models that are constructed toagree with both the observed low luminosity and the gravity field data. Ourmodels make use of modern ab initio equations of state at high pressures forthe icy components water, methane, and ammonia. Proceeding step by step, weconfirm that adiabatic models yield cooling times that are too long, even whenuncertainties in the ice:rock ratio (I:R) are taken into account. We then arguethat the transition between the ice/rock-rich interior and the H/He-rich outerenvelope should be stably stratified. Therefore, we introduce a simple thermalboundary and adjust it to reproduce the low luminosity. Due to this thermalboundary, the deep interior of the Uranus models are up to 2--3 warmer thanadiabatic models, necessitating the presence of rocks in the deep interior witha possible I:R of $1\times$ solar. Finally, we allow for an equilibriumevolution (Teff ~ Teq) that begun prior to the present day, which wouldtherefore no longer require the current era to be a "special time" in Uranus'evolution. In this scenario, the thermal boundary leads to more rapid coolingof the outer envelope. When Teff ~ Teq is reached, a shallow, subadiabatic zonein the atmosphere begins to develop. Its depth is adjusted to meet theluminosity constraint. This work provides a simple foundation for future IceGiant structure and evolution models, that can be improved by properly treatingthe heat and particle fluxes in the diffusive zones.

This article considers the "agency of images" in "mediating identity" of the Genoese admiral Andrea Doria (1466-1560).  Doria was represented in an extraordinary group of portraits as an ancient Roman sea captain and nude Neptune, god of the seas.  These historical and mythological portraits are considered in relation to Charles V's Hapsburg Augustan imperial iconography and ancient Roman ideas about the Mediterranean Sea, mare nostrum.

We describe a method that does not use any orbital parameters, to arrive at the position and mass of a new celestial object, using high-precision orbital state vector data of the rest of the objects in the system. As an illustration of this approach, we rediscover Neptune with remarkable accuracy. [ABSTRACT FROM AUTHOR]

Radio observations of the atmospheres of the giant planets Jupiter, Saturn, Uranus, and Neptune have provided invaluable constraints on atmospheric dynamics, physics/chemistry, and planet formation theories over the past 70 years. We provide a brief history of these observations, with a focus on recent and state-of-the-art studies. The global circulation patterns, as derived from these data, in combination with observations at UV/visible/near-IR wavelengths and in the thermal infrared, suggest a vertically-stacked pattern of circulation cells in the troposphere, with the top cell similar to the classical picture, overlying cells with the opposite circulation. Data on the planets’ bulk compositions are used to support or disfavor different planet formation scenarios. While heavy element enrichment in the planets favors the core accretion model, we discuss how the observed relative enrichments in volatile species constrain models of the outer proto-planetary disk and ice giant accretion. Radio observations of planets will remain invaluable in the next decades, and we close with some comments on the scientific gain promised by proposed and under-construction radio telescopes.

In support of studies of decadal-timescale evolution of outer solar system atmospheres and ring systems, we present detailed Earth-based stellar occultation predictions for Jupiter, Saturn, Uranus, Neptune, Titan, and Triton for 2023–2050, based on the Gaia Data Release 3 star catalog and near-IR K -band photometry from the Two Micron All Sky Survey catalog. We tabulate the number of observable events by year and magnitude interval, reflecting the highly variable frequency of high-signal-to-noise ratio (S/N) events depending on the target’s path relative to the star-rich regions of the Milky Way. We identify regions on Earth where each event is potentially observable, and for atmospheric occultations we determine the latitude of the ingress and egress events. For Saturn, Uranus, and Neptune, we also compute the predicted ring occultation event times. We present representative subsets of the predicted events and highlight particularly promising events. Jupiter occultations with K ≤ 7 occur at a cadence of about one per year, with bright events at higher frequency in 2031 and 2043. Saturn occultations are much rarer, with only two predicted events with K ≤ 5 in 2032 and 2047. Ten Uranus ring occultations are predicted with K ≤ 10 for the period 2023–2050. Neptune traverses star-poor regions of the sky until 2068, resulting in only 13 predicted occultations for K ≤ 12 between 2023 and 2050. Titan has several high-S/N events between 2029 and 2031, whereas Triton is limited to a total of 22 occultations with K ≤ 15 between 2023 and 2050. Details of all predicted events are included in the Supplementary Online Material.

The tilt between Neptune's magnetic and rotational axes, along with Triton's orbital obliquity, causes a strong time variability of the moon's local electromagnetic environment. To constrain Triton's interaction with the ambient magnetospheric plasma, we apply a hybrid (kinetic ions, fluid electrons) model including the moon's ionosphere and induced field. To represent the extremes in the changes to the local electromagnetic field over a synodic rotation, we consider two orientations between the ambient magnetic field and flow velocity. For each, we first investigate the (analytical) magnetic signatures associated with the superposition of Triton's induced field and the magnetospheric field in the absence of any plasma interaction effects. To constrain the effect of Triton's ionosphere on the currents, we model the interaction between the ionospheric and magnetospheric plasma in isolation from the moon's inductive response, before combining these effects to investigate the complex scenario of plasma interaction and induction. Finally, we explore the sensitivity of the plasma interaction to changes in the ambient plasma density and the strength of Triton's inductive response. Despite plasma interaction signatures that dominate the plasma perturbations far from the moon (beyond ∼3 Triton radii), we illustrate that the induced field is clearly discernible within ∼3 Triton radii, regardless of the moon's location within Neptune's magnetosphere. We find that the orientation of the magnetospheric field and velocity vectors strongly affects Triton's plasma interaction; at times, resembling those of Jupiter's or Saturn's moons, while at others, revealing unprecedented signatures that are likely unique to moons of the ice giants. Key Points: We constrain the time variability in signatures associated with plasma interaction and induction at Triton, Neptune's largest moonDespite the presence of plasma currents far from the moon, Triton's induced field dominates the near‐surface magnetic field perturbationsThe tilt of Neptune's magnetic and rotation axes generates a plasma wake that is strongly displaced out of Triton's geometric plasma shadow [ABSTRACT FROM AUTHOR]

The hundreds of exoplanets that have been discovered in the past two decades offer a new perspective on planetary structure. Instead of being the archetypal examples of planets, those of our solar system are merely possible outcomes of planetary system formation and evolution, and conceivably not even especially common outcomes (although this remains an open question). Here, we review the diverse range of interior structures that are both known and speculated to exist in exoplanetary systems--from mostly degenerate objects that are more than 10× as massive as Jupiter, to intermediate-mass Neptune-like objects with large cores and moderate hydrogen/helium envelopes, to rocky objects with roughly the mass of Earth.

Inconsistencies in the preparation of histology slides and whole‐slide images (WSIs) may lead to challenges with subsequent image analysis and machine learning approaches for interrogating the WSI. These variabilities are especially pronounced in multicenter cohorts, where batch effects (i.e. systematic technical artifacts unrelated to biological variability) may introduce biases to machine learning algorithms. To date, manual quality control (QC) has been the de facto standard for dataset curation, but remains highly subjective and is too laborious in light of the increasing scale of tissue slide digitization efforts. This study aimed to evaluate a computer‐aided QC pipeline for facilitating a reproducible QC process of WSI datasets. An open source tool, HistoQC, was employed to identify image artifacts and compute quantitative metrics describing visual attributes of WSIs to the Nephrotic Syndrome Study Network (NEPTUNE) digital pathology repository. A comparison in inter‐reader concordance between HistoQC aided and unaided curation was performed to quantify improvements in curation reproducibility. HistoQC metrics were additionally employed to quantify the presence of batch effects within NEPTUNE WSIs. Of the 1814 WSIs (458 H&E, 470 PAS, 438 silver, 448 trichrome) from n = 512 cases considered in this study, approximately 9% (163) were identified as unsuitable for subsequent computational analysis. The concordance in the identification of these WSIs among computational pathologists rose from moderate (Gwet's AC1 range 0.43 to 0.59 across stains) to excellent (Gwet's AC1 range 0.79 to 0.93 across stains) agreement when aided by HistoQC. Furthermore, statistically significant batch effects (p < 0.001) in the NEPTUNE WSI dataset were discovered. Taken together, our findings strongly suggest that quantitative QC is a necessary step in the curation of digital pathology cohorts. © 2020 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The surface zonal winds observed in the giant planets form a complex jet pattern with alternating prograde and retrograde direction. While the main equatorial band is prograde on the gas giants, both ice giants have a pronounced retrograde equatorial jet.We use three-dimensional numerical models of compressible convection in rotating spherical shells to explore the properties of zonal flows in different regimes where either rotation or buoyancy dominates the force balance. We conduct a systematic parameter study to quantify the dependence of zonal flows on the background density stratification and the driving of convection.In our numerical models, we find that the direction of the equatorial zonal wind is controlled by the ratio of the global-scale buoyancy force and the Coriolis force. The prograde equatorial band maintained by Reynolds stresses is found in the rotation-dominated regime. In cases where buoyancy dominates Coriolis force, the angular momentum per unit mass is homogenized and the equatorial band is retrograde, reminiscent to those observed in the ice giants. In this regime, the amplitude of the zonal jets depends on the background density contrast with strongly stratified models producing stronger jets than comparable weakly stratified cases. Furthermore, our results can help to explain the transition between solar-like (i.e. prograde at the equator) and the "anti-solar" differential rotations (i.e. retrograde at the equator) found in anelastic models of stellar convection zones.In the strongly stratified cases, we find that the leading order force balance can significantly vary with depth. While the flow in the deep interior is dominated by rotation, buoyancy can indeed become larger than Coriolis force in a thin region close to the surface. This so-called "transitional regime" has a visible signature in the main equatorial jet which shows a pronounced dimple where flow amplitudes notably decay towards the equator. A similar dimple is observed on Jupiter, which suggests that convection in the planet interior could possibly operate in this regime. © 2013 Elsevier Inc.