Water Archives

Ionic liquids. (A) schematic of an ionic liquid composed of a hydrogen sulfate anion and a glycine cation. (B) Vials of selected ionic liquids composed of N-containing organics and hydrogen sulfate anions, compounds as labeled in the image. Ionic liquids are typically transparent, with a range of chemical characteristics including colors and viscosities. The ionic liquids were generated by evaporating excess sulfuric acid from mixtures of various organic compounds and concentrated sulfuric acid. -- PNAS

Astrochemistry, Astrogeology, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Biophysics, Biosignatures & Paleobiology, Genomics, Proteomics, Bioinformatics, Habitable Zones, Press Release

Planets Without Water Could Still Produce Certain Liquids

by Keith CowingAugust 12, 2025August 12, 2025

Water is essential for life on Earth. So, the liquid must be a requirement for life on other worlds. For decades, scientists’ definition of habitability on other planets has rested […]

Stacked images of interstellar comet 3I/ATLAS acquired with UVOT obtained on July 31 and Aug 1, 2025. The image acquired with the V filter is shown on the left, the UVW1 image is shown on the right. Apertures used are shown in red, with background sky annulus in dotted white. The UVW1 aperture is ≈ 20, 000 km, background annulus radii are 60,000 and 80,000 km. Ticks along the bottom represent 20,000 km. Color scales are optimized for viewing. -- astro-ph.EP

Astrochemistry, Astrogeology, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Comets and Asteroids, Icy Worlds, Imaging & Spectroscopy, Interstellar, Press Release

Water Detection in the Interstellar Object 3I/ATLAS

by Keith CowingAugust 7, 2025August 7, 2025

We report the first detection of water activity in the third confirmed interstellar object, 3I/ATLAS, based on ultraviolet imaging with the Neil Gehrels-Swift Observatory.

NIRSpec spectrum of L1527 on the optical depth scale from 3.7-4.2 µm (solid black trace) along with the ice fit components CH3OH (dash-dotted brown trace), a Gaussian representing SH-bearing ices (dotted yellow trace), amorphous HDO (solid blue trace), crystalline HDO (solid magenta trace), and the total combined ice fit (dashed green trace). The gray horizontal shaded region indicates the 3σ noise level. See Figure B.1 for the local continuum used to extract this spectrum. astro-ph.SR

Astrochemistry, Astronomy & Telescopes, Biosignatures & Paleobiology, Icy Worlds, Imaging & Spectroscopy, Interstellar, Status Report

HDO Ice Detected Toward An Isolated Low-mass Protostar With JWST

by Keith CowingJuly 28, 2025July 28, 2025

Water is detected in environments representing every stage of star and solar system formation, but its chemical evolution throughout these stages remains poorly constrained.

This is an example of a debris-covered glacier on Mars. New research into these features suggests that they are purer than once thought, with implications for understanding Mars’ overall water budget and resource utilization on future crewed missions. Credit: NASA/JPL-Caltech/University of Arizona

Astrogeology, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Icy Worlds, Imaging & Spectroscopy, Mapping, Geodesy, Cartography, Bathymetry, Mars, Press Release

Mars Glaciers Are Purer And More Uniform Than Previously Thought

by Keith CowingJuly 25, 2025July 25, 2025

On the slopes of Martian mountains and craters clings what appears to be flowing honey, coated in dust and frozen in time. In reality, these features are incredibly slow-moving glaciers, […]

Illustration of the range of possible internal compositions for temperate sub-Neptunes like K2-18 b, and a roadmap to characterize them through atmospheric observations. A liquid-water ocean separating the atmosphere from the interior necessarily implies a small atmosphere, which may be composed of either H2 or heavier molecules. In contrast, a massive atmosphere is expected to be well-mixed with the volatile envelope underneath. We propose characterizing such massive envelopes along two principal axes: the H2-to-H2O ratio and the metallicities defined by carbon, nitrogen, and sulfur. In a standard H2-dominated envelope, the oxygen abundance tracks that of C, N, and S with the solar abundance ratio. In a mixed or steam-rich envelope, oxygen (and thus H2O) is more abundant; in a soot-rich envelope, it is less so. Nitrogen and sulfur may be depleted relative to carbon due to preferential partitioning into the mantle or core. The existence of a water-dominated layer between the envelope and the rocky interior remains uncertain, but is retained here as a possibility. Regardless of envelope composition, water may condense in the atmospheres of K2-18 b and cooler sub-Neptunes, rendering direct H2O measurements from transmission spectra unreliable as diagnostics of the bulk composition. Instead, detecting and quantifying a suite of gases, such as CH4, CO2, CO, NH3, and SO2, and their relative abundances offers a more robust pathway to distinguish among envelope compositions, physical states, and the potential presence of a liquid-water ocean. -- astro-ph.EP

Astrogeology, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Icy Worlds, Imaging & Spectroscopy, Status Report, Water/Hycean Worlds & Oceanography

A Water-rich Interior In The Temperate Sub-Neptune K2-18 b Revealed By JWST

by Keith CowingJuly 18, 2025July 18, 2025

Temperate sub-Neptunes Are Compelling Targets For Detecting Liquid-water Oceans Beyond The Solar System. If water-rich and lacking massive hydrogen-helium envelopes, these planets could sustain liquid layers beneath their atmospheres despite […]

Atmospheres, Climate, Weather, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Habitable Zones, Icy Worlds, Status Report, Water/Hycean Worlds & Oceanography

On The Relative Humidity Of Earth’s Atmosphere

by Keith CowingJuly 17, 2025July 17, 2025

Water vapour is highly subsaturated in much of the Earth’s atmosphere. This has important consequences for water vapour feedback, and also for general phenomena such as the runaway greenhouse.

Top view of the Milky Way galaxy showing the estimated orbits of both our Sun and the 3I/ATLAS comet. 3I/ATLAS is shown in red dashed lines, and the Sun is shown in yellow dotted lines. The large extent of 3I’s orbit into the outer thick disk is clear, while the Sun stays nearer the core of the galaxy. Credit M. Hopkins/Ōtautahi-Oxford team. Base map: ESA/Gaia/DPAC, Stefan Payne-Wardenaar, CC-BY-SA 4.0 Licence type Attribution (CC BY 4.0)

Astrochemistry, Astrogeology, Astronomy & Telescopes, Biosignatures & Paleobiology, Icy Worlds, Imaging & Spectroscopy, Interstellar, Press Release

Interstellar Object 3I/ATLAS May Be The Oldest Comet Ever Seen

by Keith CowingJuly 12, 2025July 12, 2025

A mystery interstellar object discovered last week is likely to be the oldest comet ever seen – possibly predating our solar system by more than three billion years, researchers say.

Water-equivalent content by weight in the Solar System and model predictions. Left upper panel: Midplane temperature of the disk using T1au = 145, 180, 200 and 300 K (from light blue to dark blue respectively) in Eq. 2. Left lower panel: The solid curves show the snowlines calculated using the Tinacci et al. (2023) BE distribution for the different temperature profiles (colours code as above). The data points show the median values of the water-equivalent content by weight for different objects of the Solar System (Sec. 3), where vertical bars represent the minimum and maximum range. Please note that the values reported in Tab. 1 are considered upper limits (see text). The uncertainty of the formation region of the various objects are shown as ellipses, distinguishing NC, CC, and comet populations. Right: Computed snowlines using T1au = 200 K in Eq. 2 and different models (see text): BE distribution (solid line), single BE (dashed) and condensation at 180 K (dotted). The right and left panels share the same vertical axis. -- astro-ph.EP

Astrochemistry, Astrogeology, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Habitable Zones, Interstellar, Status Report, Water/Hycean Worlds & Oceanography

Was Earth’s Water Acquired Locally During The Earliest Phases Of The Solar System Formation?

by Keith CowingJuly 8, 2025July 8, 2025

The origin of the terrestrial water remains debated, as standard Solar System formation models suggest that Earth formed from dry grains, inside the snowline of the Proto-Solar Nebula (PSN).

Envelope H2O mass fraction as a function of semi-major axis. The same dataset as in Figure 1 is shown. The left panel shows planets that predominantly formed inside the water ice line; the right panel shows those that formed outside. Classification is based on the accreted H2O mass fraction, with a threshold set at 5% of the total planetary mass. The colorbar indicates the molar bulk C/O ratio. Planets formed inside the ice line are systematically depleted in carbon due to the lack of volatile ice accretion and exhibit higher envelope H2O mass fractions. In contrast, planets formed beyond the ice line retain lower H2O content despite higher bulk volatile abundances. Each pie chart shows the mean mass fraction of hydrogen in H2 (gas), H (metal), H2 (silicate), H2O (gas), and H2O (silicate), normalized to the total mean hydrogen inventory for each population. Only components contributing more than 5% are labeled. Planets that formed beyond the ice line store most hydrogen as H2 (gas) and H (metal), while those that formed inside the ice line retain a larger share of hydrogen in H (metal) H2 (silicate) and H2O (gas + silicate). -- astro-ph.EP

Astrochemistry, Astrogeology, Atmospheres, Climate, Weather, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Ice Giant, Icy Worlds, Status Report, Water/Hycean Worlds & Oceanography

Sub-Neptunes Are Drier Than They Seem: Rethinking the Origins of Water-Rich Worlds

by Keith CowingJuly 3, 2025July 3, 2025

Recent claims of biosignature gases in sub-Neptune atmospheres have renewed interest in water-rich sub-Neptunes with surface oceans, often referred to as Hycean planets.