Ice Giant Archives

Models for Neptune and Uranus derived in this study expressed as density versus radius. Contour colors show density. Key elements of the models are labelled. The bright narrow band at the base of the envelope in each case is the boundary region stable against convection, ∼ 120 km and ∼ 180 km wide in the cases of Neptune and Uranus, respectively. -- astro-ph.EP

Astrogeology, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Ice Giant, Lava / magma ocean / Volcanic Worlds, Neptune, Status Report, Uranus, Water/Hycean Worlds & Oceanography

Ice Giants Revisited: Uranus And Neptune As Magma Ocean Worlds

by Keith CowingJune 18, 2026June 18, 2026

Uranus and Neptune are commonly interpreted as volatile-rich “ice giants”, an assumption that underpins most interior models.

Example Uranus orbit insertion outside the zeta ring. Uranus orbit insertion maneuver traverses Uranus’s ring plane in the epsilon-ν ring gap (left). Uranus orbit insertion (UOI) burn (1.62 hr duration, 1331 m s−1) as viewed from Earth (right). While this example occurs in full view of ground stations, this is not a feature of all UOI geometries, where some portion of the burn is typically occulted with respect to Earth. Uranus’s orbital velocity vector is indicated for reference. Reproduced from D. Ellison et al. (2025).

Atmospheres, Climate, Weather, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Ice Giant, Imaging & Spectroscopy, Missions & Hardware, Status Report, Uranus

Uranus Orbiter and Probe: Mission Challenges and Concept Updates Since the Origins, Worlds, and Life Decadal Survey

by Keith CowingJune 14, 2026June 14, 2026

Origins, Worlds, and Life: Planetary Science and Astrobiology in the Next Decade identified a Uranus Orbiter and Probe as the highest-priority strategic mission for the decade 2023–2032, as it enables […]

Left: Radiative cooling rates for TOI-238 b: the H-He atmosphere with solar metallicity (top panel) and the atmosphere enriched in metals 200 times over solar metallicity (bottom panel). The plot format matches that of Fig. 2. Center: Volume heating rates for TOI-238 b: the H-He atmosphere with solar metallicity (top panel) and the atmosphere enriched in metals 200 times over solar metallicity (bottom panel). The plot format matches that of Fig. 3. Right: Population of hydrogen species and heavy (metal) ions: the H-He atmosphere with solar metallicity (top panel) and the atmosphere enriched in metals 200 times over solar metallicity (bottom panel). The plot format matches that of Fig. 4. -- astro-ph.EP

Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Exoplanets, -moons, -comets, Ice Giant, Imaging & Spectroscopy, Status Report

Escape Of Water- And Metal-enriched Atmospheres From Compact Hot mini-Neptunes With CHAIN

by Keith CowingJune 3, 2026June 3, 2026

Recent observations reveal that atmospheric compositions of close-in sub-Neptunes are diverse and can differ strongly from pure H/He-dominated.

This plot shows currently known exoplanets, with different categories highlighted. Roman will help fill in the bottom-right of the plot by finding small worlds in large orbits. NASA’s Goddard Space Flight Center

Astrochemistry, Astronomy & Telescopes, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Gas Giants, Ice Giant, Imaging & Spectroscopy, Press Release

NASA’s Roman Mission Preps to Unveil New Populations of Faraway Worlds

by Keith CowingMay 29, 2026May 29, 2026

NASA’s Nancy Grace Roman Space Telescope is poised to make a major leap in the hunt for worlds outside our solar system, known as exoplanets. Scientists expect the mission to […]

Each panel shows the T(P) profiles for the clear atmosphere (red line) and cloudy atmosphere (blue line) computed for a sub-Neptune belonging to our sample of 8 sub-Neptunes. The phases of the interfaces for TOI-270 d and TOI-1231 b are shown in Figure 5, while those for the rest of the sub-Neptunes in our sample are shown here. Similar to Figure 5, the thicker lines depict the convective regions of the atmosphere. The locus of blue and red crosses show the P and T locations of the atmosphere-mantle interface computed by coupling our atmosphere model with the interior structure model for the cloudy and clear models, respectively. The P − T location and the T(P) profiles are overlaid on the phase–diagram for silicates, depicting its solid and molten phases as blue and red shaded regions. -- astro-ph.EP

Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Ice Giant, Imaging & Spectroscopy, Status Report, Water/Hycean Worlds & Oceanography

Impact of Clouds on the Atmosphere-Mantle Interface of Sub-Neptunes

by Keith CowingMay 29, 2026May 29, 2026

Sub-Neptunes are among the most common type of close-in planets found in our galaxy, yet their bulk composition remains largely uncertain; H-rich envelopes overlaying rocky cores, volatile-rich planets, and carbon-rich […]

Integrated flux for ALMA’s CO(3-2) line measurement. Superposed as black circles on Neptune’s map are the beam positions observed onto the planet and used for the spatially resolved retrievals. The filled red circle in the lower-left corner indicates the size and orientation of the beam. -- astro-ph.EP

Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Ice Giant, Neptune, Status Report

Latitudinal Variations In Neptune’s Temperature Profile Observed With ALMA

by Keith CowingMay 26, 2026May 26, 2026

Despite the low solar irradiation it receives, Neptune shows a very active atmosphere with some of the most intense dynamics observed in Solar System atmospheres. Characterizing the atmospheric temperature profiles […]

Thermal evolution of a 1 M⊕ model with no atmosphere (top row) and a model with a thin 0.01% H-He by mass atmosphere/envelope.

Astrochemistry, Astrogeology, Desert Worlds, Exoplanets, -moons, -comets, Gas Giants, Ice Giant, Icy Worlds, Status Report, Water/Hycean Worlds & Oceanography

ORCHARD: A General Planetary Evolution Code

by Keith CowingApril 30, 2026April 30, 2026

We present ORCHARD, a publicly available planetary evolution code based on the gas giant evolution code, APPLE, capable of modeling the evolution and structures of terrestrial, super-Earth, sub-Neptune, Neptune, and […]

Details of the interior models of Uranus and Neptune. Top: Illustration of the three-layer internal structure model assumed. Both the envelope and mantle contain hydrogen, helium, ices, and rocks, with the mantle expected to have a higher concentration of ices and rocks. The core is composed entirely of rocks. Bottom: Envelope metallicity versus mantle metallicity for interior models of Uranus and Neptune. Each dot represents a model that fits both the gravitational data and radius of the respective planet. The color scale indicates the core mass. -- astro-ph.EP

Astrogeology, Exoplanets, -moons, -comets, Ice Giant, Icy Worlds, Neptune, Status Report, Uranus

Reassessing Planetary Composition: Evidence Of Rock-dominated Envelopes In Uranus And Neptune

by Keith CowingApril 17, 2026April 17, 2026

Although Uranus and Neptune are commonly classified as ice giants, their exact compositions remain poorly constrained. Recent studies of outer Solar System bodies challenge the traditional view that these planets […]

Effect of water dissolution on planetary radius (adapted from Luo et al (2024)). All interiors share identical bulk composition but differ in model assumptions. Classical models separated volatiles and refractories, and ignored melts (A). Alternative models that include melts but neglected volatile dissolution overestimate planetary radii (B). The water dissolution in the mantle (C) or mantle and core (D) reduces them. Scenario (D) is considered most realistic for hot super-Earths with magma oceans. -- astro-ph.EP

Exoplanets, -moons, -comets, Ice Giant, Status Report, Stellar Cartography

Origin And Characterization Of Super-Earths And Sub-Neptunes

by Keith CowingApril 15, 2026April 15, 2026

Super-Earths and sub-Neptunes represent the most common class of exoplanets discovered to date in our galaxy, yet they have no direct analogues in the Solar System. Since 2014, researchers within […]

Fully corrected and calibrated albedos of Titan (yellow), Saturn (green), Uranus (blue), and Neptune (red) covering 0.3 µm to 2.1 µm, offset for clarity. Regions of strong telluric absorption are masked in lighter shades, and it should be noted that they are less reliably corrected. The flat regions in the UV were flagged as bad pixels in all images by X-shooter. We also highlight a vertical discontinuity between the VIS and NIR arms of Titan, which is likely due to weather inconsistency. The colors used for these objects are the same in the following figures. -- Astronomy & Astrophysics

Astrochemistry, Astrogeology, Astronomy & Telescopes, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Gas Giants, Ice Giant, Jupiter, Mars, Mercury, Neptune, Saturn, Status Report, Titan, Uranus

HiDef Neighbors: Solar System Objects As Exoplanet Analogs I. Gaseous Objects, Planets, Planetary Systems, And Small Bodies

by Keith CowingMarch 27, 2026

Context. Intermediate-resolution spectral observations are vital tools for characterizing the composition and physical properties of Solar System bodies in detail. At present, the planets and moons of our Solar System […]

Ice Giant

Ice Giants Revisited: Uranus And Neptune As Magma Ocean Worlds

Uranus Orbiter and Probe: Mission Challenges and Concept Updates Since the Origins, Worlds, and Life Decadal Survey

Escape Of Water- And Metal-enriched Atmospheres From Compact Hot mini-Neptunes With CHAIN

NASA’s Roman Mission Preps to Unveil New Populations of Faraway Worlds

Impact of Clouds on the Atmosphere-Mantle Interface of Sub-Neptunes

Latitudinal Variations In Neptune’s Temperature Profile Observed With ALMA

ORCHARD: A General Planetary Evolution Code

Reassessing Planetary Composition: Evidence Of Rock-dominated Envelopes In Uranus And Neptune

Origin And Characterization Of Super-Earths And Sub-Neptunes

HiDef Neighbors: Solar System Objects As Exoplanet Analogs I. Gaseous Objects, Planets, Planetary Systems, And Small Bodies

PJ Harvey Announces New Song “Voyager”

Fifty Years after Viking: The Promise of Solar System Microbiology and Microbial Ecology

Characterising Transiting Exoplanets At Long Orbital Period: Lessons Learned For PLATO From 10 Years Of Monitoring The HIP41378 System

Implications Of Self-consistent H2O Ice Optical Constants On Radiative Transfer Models Of Disks

The GAPS Programme at TNG LXXIV. A Reanalysis Of The Planetary Systems TOI-1272 And TOI-1694 With HARPS-N And Retraction Of The Planetary Interpretation Of TOI-1272 c