Neptune Archives

Sketches of the two end-members of possible bulk compositions of Uranus and Neptune: a water-dominated interior (left) and a rock-dominated interior (right). The dark brown at the planetary center represents the core, which is expected to be composed of iron and rocks. The atmosphere is represented with gray. Note that the transition between different layers may be fuzzy and that currently it is still unknown whether the planetary interiors are differentiated with distinct compositional layers. Keck Institute for Space Studies / Chuck Carter

Astrochemistry, Atmospheres, Climate, Weather, Exploration Gear & Tech, Gas Giants, Icy Worlds, Neptune, Status Report, Uranus

Ice Giants

by Keith CowingApril 29, 2025April 29, 2025

Uranus and Neptune, the so-called “ice giants”, represent a fascinating class of planets. They are the outermost planets in the solar system with intermediate masses/sizes, complex non-polar magnetic fields, strong […]

Comparison of TOI-6478 b (diamond) to the known exoplanet population. Left: Planet radius vs orbital period for exoplanets with equilibrium temperatures (color bar) < 250 K and radii > 2R⊕. One year is highlighted by the dashed grey line. Of these 25 exoplanets, only 9 are colder than TOI6478 b, but all have orbital periods at least 3× larger. Solar systems planets are shown as reference. Right: Mass-radius diagram with key mass-radius relations highlighted with coloured dashed lines. TOI-6478 b is shown as the pink diamond, placed at the upper-mass limit from the current RVs. Solar system planets (black diamonds) are shown as reference. -- astro-ph.EP

Astrogeology, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Status Report

TOI-6478 b: A Cold Under-dense Neptune Transiting A Fully Convective M Dwarf From The Thick Disc

by Keith CowingApril 11, 2025April 11, 2025

Growing numbers of exoplanet detections continue to reveal the diverse nature of planetary systems. Planet formation around late-type M dwarfs is of particular interest.

At the left, an enhanced-color image of Neptune from NASA’s Hubble Space Telescope. At the right, that image is combined with data from NASA’s James Webb Space Telescope. The cyan splotches, which represent auroral activity, and white clouds, are data from Webb’s Near-Infrared Spectrograph (NIRSpec), overlayed on top of the full image of the planet from Hubble’s Wide Field Camera 3. - STSCI

Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Ice Giant, Icy Worlds, Imaging & Spectroscopy, Neptune, People Of Astrobiology, Press Release, Radiation, Space Weather & Heliophysics

Webb Space Telescope Captures Neptune’s Auroras For First Time

by Keith CowingApril 4, 2025May 12, 2025

For the first time, NASA’s James Webb Space Telescope has captured bright auroral activity on Neptune. Auroras occur when energetic particles, often originating from the Sun, become trapped in a […]

Artist’s impression of GJ 1214 b passing in front of its host star. The “transit method” allows astronomers to study an exoplanet by seeing which wavelengths of light dim when the star’s light passes through the exoplanet atmosphere. (Credit: NAOJ)

Exoplanets, -moons, -comets, Icy Worlds, Neptune, Press Release, Venus

Super-Earth vs. Sub-Neptune? The Winner is Super-Venus

by Keith CowingJanuary 20, 2025January 19, 2025

New observational data from the James Webb Space Telescope and simulation models have confirmed a new type of planet unlike anything found in the Solar System. This provides another piece […]

This is a montage of NASA Hubble Space Telescope views of our solar system's four giant outer planets: Jupiter, Saturn, Uranus, and Neptune, each shown in enhanced color. The images were taken over nearly 10 years, from 2014 to 2024. This long baseline allows astronomers to track seasonal changes in each planet's turbulent atmosphere, with the sharpness of the NASA planetary flyby probes of the 1980s. These images were taken under a program called OPAL (Outer Planet Atmospheres Legacy). NASA, ESA, Amy Simon (NASA-GSFC), Michael H. Wong (UC Berkeley); Image Processing: Joseph DePasquale (STScI)

Astronomy & Telescopes, Imaging & Spectroscopy, Jupiter, Neptune, Press Release, Saturn, Uranus

Hubble Celebrates A Decade Of Tracking Outer Planets

by Keith CowingDecember 10, 2024December 10, 2024

Encountering Neptune in 1989, NASA’s Voyager mission completed humankind’s first close-up exploration of the four giant outer planets of our solar system. Collectively, since their launch in 1977, the twin […]

Magnetic field of Uranus. (left) Magnetic field line geometry of Uranus for Winter Solstice and Spring Equinox in the Uranus–Sun–Orbit frame. The orbits of Miranda, Ariel, Umbriel, Titania and Oberon are shown. Independent of season, the magnetic field of Umbriel (as well as Miranda and Ariel) is well shielded from external effects of the magnetosphere, making it a robust target for magnetic induction investigation of its interior (right) Fourier transform of the magnetic field of Uranus evaluated at the position of Umbriel. Note that although there are many beats and harmonics of the two fundamental frequencies, only the synodic is used here for characterization owing to its dominance over the other frequencies. -- Philos Trans A Math Phys Eng Sci via PubMed

Ariel, Astrogeology, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Europa, Exploration Gear & Tech, Ganymede, Ice Giant, Icy Worlds, Magnetic Fields, Electromagnetism, bioelectricity,, Miranda, Oberon, Status Report, Titania, Umbriel, Uranus, Water/Hycean Worlds & Oceanography

Detecting Planetary Oceans: Application To The Uranus System

by Keith CowingDecember 8, 2024May 12, 2025

The discovery of Europa’s subsurface ocean has spawned a strong desire by the planetary community to return and assess the ocean’s habitability using the magnetic induction signal that Europa generates.

Models for the interior structures of the ice-giant planets Uranus and Neptune have two distinct, intermediate layers: an upper, water-rich convecting layer where disorganized magnetic fields are generated, and a lower, non-convecting hydrocarbon-rich layer. New computer simulations show that icy materials naturally separate at high pressure and temperature into these two layers. Credit Burkhard Militzer, UC Berkeley

Astrogeology, Atmospheres, Climate, Weather, Ice Giant, Icy Worlds, Neptune, Press Release, Uranus, Water/Hycean Worlds & Oceanography

A Clue To What Lies Beneath The Bland Surfaces Of Uranus And Neptune

by Keith CowingNovember 26, 2024May 12, 2025

Diamond rain? Super-ionic water? These are just two proposals that planetary scientists have come up with for what lies beneath the thick, bluish, hydrogen-and-helium atmospheres of Uranus and Neptune, our […]

Reprocessed images show the true colors of Uranus (left) and Neptune. — University of Oxford

Astrochemistry, Astrogeology, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Ice Giant, Icy Worlds, Neptune, Status Report, Uranus, Water/Hycean Worlds & Oceanography

H2-H2O Demixing In Uranus And Neptune: Adiabatic Structure Models

by Keith CowingOctober 30, 2024May 12, 2025

Demixing properties of planetary major constituents influence the interior structure and evolution of planets. Comparing experimental and computational data on the miscibility of hydrogen and water to adiabatic profiles suggests […]

A schematic diagram of the sulfur cycle on the icy Galilean moons. Not all processes operate on all moons and the circles with E, G, and C indicate which processes seem to be more restricted to Europa, Ganymede, and Callisto, respectively. Ice radiolysis happens on all icy surfaces and reactions of radiolytically produced H2SO4 can transform brine salts to sulfates. Only for Europa and Callisto the subsurface ocean is likely to be in contact with the rocky ocean floor but not for Ganymede, where massive dense ice layers prevents ongoing exchange of the subsurface with the silicates. The ocean compositions seem to be all quite similar in the beginning, and Ganymede’s ocean might be the oldest ur-ocean remaining since isolation by dense ice. Subsurface oceans on Europa and Callisto can evolve depending on silicate mantle outgassing into the oceans which may increase salinity over time. On Europa acidification from radiolytically produced H2SO4 may happen, which could lead to an ocean with compositional gradients and pH and development of a halocline. This diagram does not claim completeness and is an attempt to summarize observations, ideas and interpretations. -- astro-ph.EP

Astrochemistry, Astrogeology, Atmospheres, Climate, Weather, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Enceladus, Europa, Ganymede, Gas Giants, Icy Worlds, Imaging & Spectroscopy, Io, Jupiter, Mapping, Geodesy, Cartography, Bathymetry, Neptune, Saturn, Status Report, Titan, Uranus

Sulfur in the Giant Planets, their Moons, and Extrasolar Gas Giant Planets

by Keith CowingOctober 18, 2024October 18, 2024

We review sulfur chemistry of the gas giant planets and their moons where sulfur compounds are observed. The major S-bearing gas in the upper atmospheres of the giant planets is […]

This color image from NASA Voyager 2 was reconstructed by making a computer composite of three black and white images taken through red, green, and blue filters. Details on Triton surface unfold dramatically in this sequence of approach images. Larger image

Icy Worlds, Neptune, Status Report, Triton, Water/Hycean Worlds & Oceanography

The Trans- And Post-Capture Orbital Evolution Of Triton

by Keith CowingSeptember 26, 2024September 26, 2024

Triton is a unique moon in our Solar System, being the only large moon to orbit on a retrograde and highly inclined orbit. As a result, it is thought that […]