Neptune Archives

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 […]

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 […]

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. NASA ID: PIA00329 Larger image

Astrogeology, Icy Worlds, Imaging & Spectroscopy, Mapping, Geodesy, Cartography, Bathymetry, Missions & Hardware, Neptune, Status Report, Triton, Water/Hycean Worlds & Oceanography

Enhanced Voyager 2 Approach Image Sequence Of Icy Ocean World Triton

by Keith CowingNovember 16, 2024

Original Caption Released with Image: Triton Voyager 2 approach sequence with latitude-longitude grid superposed. The color image was reconstructed by making a computer composite of three black and white images […]

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 […]

The weighted abundance of CO calculated using Equation 1 has been shown as a heat map as a function of C/O and Kzz in each panel. Each row corresponds to a different Teq value from 1100 K to 600 K from top to bottom. Each column correspond to a different Tint value between 30 K and 500 K from left to right. Note that the C/O has been shown relative to the assumed solar value of 0.458 in this plot. -- astro-ph.EP

Astronomy & Telescopes, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Gas Giants, Habitable Zones, Ice Giant, Imaging & Spectroscopy, Neptune, Status Report

Effects of Planetary Parameters on Disequilibrium Chemistry in Irradiated Planetary Atmospheres: From Gas Giants to Sub-Neptunes

by Keith CowingOctober 23, 2024May 12, 2025

A primary goal of characterizing exoplanet atmospheres is to constrain planetary bulk properties, such as their metallicity, C/O ratio, and intrinsic heat. However, there are significant uncertainties in many aspects […]

2D light curves binned to a resolution of R=100 and 40 time bins for NRS2 (top row) and NRS1 (bottom row), with both transits averaged. The normalized flux in percentage (after linearly de-trending at each wavelength) is shown in panel A. The differential time series, after dividing by the broadband for a given detector is shown in ppm in panel B. The differential light curve model is shown in panel C and the residuals of the light curve subtracted by the model are shown in panel D. The start of ingress and end of egress times are marked as vertical dashed lines. Increased and decreased transit depths relative to the broadband light curve are visible as dark and bright bands between ingress and egress. The most noticeable features are increased transit depths near 4.3 µm and 2.8 µm and decreased transit depths near 3.6 µm and 4.6 µm. -- astro-ph.EP

Astrochemistry, Atmospheres, Climate, Weather, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Neptune, Status Report

Possible Carbon Dioxide Above The Thick Aerosols Of sub-Neptune GJ 1214 b

by Keith CowingOctober 21, 2024October 21, 2024

Sub-Neptune planets with radii smaller than Neptune (3.9 Re) are the most common type of planet known to exist in The Milky Way, even though they are absent in the […]

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 […]

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 […]

Triton as seen by Voyager 2 (larger image) -- NASA

Astrogeology, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Habitable Zones, Icy Worlds, Neptune, Status Report, Triton, Water/Hycean Worlds & Oceanography

Triton’s Captured Youth: Tidal Heating Kept Triton Warm and Active for Billions of Years

by Keith CowingSeptember 25, 2024September 25, 2024

Neptune’s moon Triton has two remarkable attributes: its retrograde orbit suggests that it was captured from the Kuiper Belt, and Triton has one of the youngest surfaces of all the […]