![Left: Average ocean fraction, calculated assuming a seawater freezing point of −1.8°𝐶 for Cases 1 and 3 and 0°𝐶 for Case 2. White shows the ice, and blue ocean. Middle: The mean near-surface air temperatures. Shown within the black contours are the regions where these vary between above and below freezing over the course of a single Earth year. Right: The mean surface temperatures. Also shown within the black contours are the regions where these vary between above and below freezing over the course of a single Earth year: these regions are narrower than the air ‘perifreezing zone’.-- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/09/Sea-Ice.png?resize=1200%2C720&ssl=1)
[astro-ph.EP] Water worlds with potential deep oceans are at the forefront of currently observable exoplanetary habitability.
Ocean world
![Planets that will be observed with MIRI in transit, in JWST Cycles 1-5. As mentioned in section 5, we see a wide variety of planet sizes and equilibrium temperatures. The currently published planets are shown in black dots, and listed in Table 1 and Figure 1. We have ommitted the white dwarf planet WD 1856 b (Teq = 160K, Rp = 10.2R⊕, cycle 4), as well as the disintergrating planets K2-22 b (see section 2.1) and BD+05 4868 A b (Teq = 1820K, unknown Rp, cycle 4). -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/09/A-Homogeneous.png?resize=1200%2C720&ssl=1)
Posted inExoplanets, -moons, -comets
A Homogeneous Survey Of JWST MIRI Transmission Spectra Of 10 Exoplanets
[astro-ph.EP] The launch of JWST has enabled unprecedented atmospheric characterization of exoplanets. In particular, the JWST-MIRI instrument in the mid-infrared enables probing of molecular species that are harder to detect […]
![Phase-dependent (colors) apparent albedo spectra from our updated rfast model for an ocean-covered Earth and assuming 75% cloud coverage (left). The equivalent figure adapted from the high-fidelity Earth simulation data of Ryan & Robinson (2022) are shown for comparison (right). All spectra are at a resolving power (λ/∆λ) of 140. Deeper water bands in the rfast simulations are due to this model only including lower-atmospheric clouds, whereas the Ryan & Robinson (2022) simulations include high-altitude clouds that have lower contrast in gas absorption bands (as they obscure the deep atmosphere). -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/09/Retrieving.png?resize=1200%2C717&ssl=1)
Posted inWater/Hycean Worlds & Oceanography
Retrieving Ocean Glint Reflectance Signatures From Directly Imaged Earth-like Exoplanets
[astro-ph.EP] Future space telescopes searching for extraterrestrial life require methods to detect environments that can potentially support life.
Posted inWater/Hycean Worlds & Oceanography
Iron Helped Scientists Trace Earth’s Oxygen. Now It’s Telling A Bigger Story
[Michigan State University] For decades, scientists have studied iron preserved in ancient rocks to reconstruct how Earth’s oceans and atmosphere became rich in oxygen. A new study suggests iron has […]
Posted inWater/Hycean Worlds & Oceanography
Ocean World Exploration: 2026 American Samoa ROV + Mapping Exploration
[NOAA]. Most of the 13,581-square-mile National Marine Sanctuary of American Samoa lies far below the sunlit coral reefs visible from shore. Its protected waters include deep seamounts, abyssal plains, deep-sea […]
Posted inTricorders & Sensors
New UC Riverside Lab Focuses on Cutting Edge Astrobiology Tools
[UC Riverside] The Planetary Geochemistry and Astrobiology Laboratory is led by Assistant Professor Fabian Klenner, a new faculty member in UCR’s Department of Earth and Planetary Sciences. His research focuses […]
![(a) Schematic of Europan ice-ocean system [related image in 11]. (b) Map of sea surface temperature (◦C) showing the transition between the temperature-stratified North Atlantic Ocean and the salt-stratified Arctic Ocean; (c) Potential temperature (left) and salinity (right) profiles with depth from location near the North Pole. Different water-mass characteristics are labeled. -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/What-can.png?resize=1200%2C582&ssl=1)
Posted inWater/Hycean Worlds & Oceanography
What Can Planetary Ice Shells Teach Us about Ocean Mixing and Life, and Why Salt Matters
[astro-ph.EP] Past and present climates, both on Earth and in planetary systems, maintain ice covers with underlying oceans. This can range from sea ice in the Arctic Ocean to global […]
Posted inEuropa
The Sulfate Content Of Europa’s Subsurface Ocean and Icy Shell
[Astrobiology (Journal)] Recent models for the origin of Jupiter indicate that the Galilean satellites were mostly derived from largely unprocessed solar nebula solids and planetesimals.
Posted inExtremeophiles and Extreme Environments
Methanotrophy Under Extreme Alkalinity In A Serpentinizing System
[Nature] Serpentinization produces hyperalkaline, H2– and CH4-rich fluids that support microbial life and serve as analogs for ocean worlds such as Enceladus. While methane production in these systems has been […]
![This artist’s concept depicts a cutaway view showing Europa’s ice shell. Data used to generate a new result on the ice thickness and structure was collected by the microwave radiometer instrument on NASA’s Juno during a close flyby of the Jovian moon on Sept. 29, 2022. NASA/JPL-Caltech/SwRI/Koji Kuramura/ Gerald Eichstädt (CC BY) [Enhanced by Grok via Astrobiology.com]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/07/Why-Europa.jpg?resize=1200%2C752&ssl=1)
Posted inEuropa
Why Europa’s Hidden Ocean May Be More Difficult To Reach Than Scientists Thought
[Rutgers University] Europa, one of Jupiter’s icy moons, long has fascinated scientists because of what may lie beneath its frozen shell: a global ocean of liquid water.