as
@spaceenginesim.bsky.social pointed out,
superterra LHS 1903 b (116ly from Sol) "kind of looks like marble" so it is perfect for this
#VPGoldenTuesday :)
#SpaceEngine #VPinspired
#ThePhotoMode #TheCapturedCollective #VirtualPhotography #VPsupport #VPrepost #VPinSpace
@spaceenginesim.bsky.social pointed out,
superterra LHS 1903 b (116ly from Sol) "kind of looks like marble" so it is perfect for this
#VPGoldenTuesday :)
#SpaceEngine #VPinspired
#ThePhotoMode #TheCapturedCollective #VirtualPhotography #VPsupport #VPrepost #VPinSpace
July 14, 2026 at 6:00 AM
as
@spaceenginesim.bsky.social pointed out,
superterra LHS 1903 b (116ly from Sol) "kind of looks like marble" so it is perfect for this
#VPGoldenTuesday :)
#SpaceEngine #VPinspired
#ThePhotoMode #TheCapturedCollective #VirtualPhotography #VPsupport #VPrepost #VPinSpace
@spaceenginesim.bsky.social pointed out,
superterra LHS 1903 b (116ly from Sol) "kind of looks like marble" so it is perfect for this
#VPGoldenTuesday :)
#SpaceEngine #VPinspired
#ThePhotoMode #TheCapturedCollective #VirtualPhotography #VPsupport #VPrepost #VPinSpace
Paper day! A new paper on existence of subNeptune magma oceans, arising from a collaboration between Cambridge and my group. Lead author Robb Calder is Oli Shorttle's doctoral student. subNeptune Magma Oceans are getting to be a hot topic! arxiv.org/abs/2512.05816
Most Rocky Sub-Neptunes are Molten: Mapping the Solidification Shoreline for Gas Dwarf Exoplanets
Sub-Neptunes are the most common type of detected exoplanet, yet their observed masses and radii are degenerate with several interior structures. One possibility is that sub-Neptunes have silicate/iro...
arxiv.org
December 8, 2025 at 10:44 AM
Paper day! A new paper on existence of subNeptune magma oceans, arising from a collaboration between Cambridge and my group. Lead author Robb Calder is Oli Shorttle's doctoral student. subNeptune Magma Oceans are getting to be a hot topic! arxiv.org/abs/2512.05816
not on any of our current subNeptune targets. Hamish Innes presented some important work on subNeptune evolution tracks at #EPSCDPS2025 in Helsinki, indicating that it may be hard to reach a liquid water ocean state even under low irradiation. Stay tuned.
September 19, 2025 at 7:17 PM
not on any of our current subNeptune targets. Hamish Innes presented some important work on subNeptune evolution tracks at #EPSCDPS2025 in Helsinki, indicating that it may be hard to reach a liquid water ocean state even under low irradiation. Stay tuned.
Pointing out that the primary objections I've seen to this paper from other astronomers largely rely on the contention that K2-18b is likely a subneptune (with a supercritical atmosphere and no surface) and not a "Hycean" world
But I've long been a proponent of life on subneptunes!
But I've long been a proponent of life on subneptunes!
GUYS HOLY SHIT THIS IS THE REAL DEAL
This is genuinely strong evidence for life, to the point where it's hard to posit any alternative explanation for the observations - and I'm usually the kind of person to pooh-pooh these hypotheses
www.bbc.com/news/article...
This is genuinely strong evidence for life, to the point where it's hard to posit any alternative explanation for the observations - and I'm usually the kind of person to pooh-pooh these hypotheses
www.bbc.com/news/article...
Promising hints of life found on distant planet K2-18b
Scientists find new but tentative evidence that a faraway world orbiting another star may be home to life.
www.bbc.com
April 17, 2025 at 12:55 PM
Pointing out that the primary objections I've seen to this paper from other astronomers largely rely on the contention that K2-18b is likely a subneptune (with a supercritical atmosphere and no surface) and not a "Hycean" world
But I've long been a proponent of life on subneptunes!
But I've long been a proponent of life on subneptunes!
The key climate modelling papers are my ApJ paper “Runaway Greenhouse on subNeptune water worlds,” and the paper by student Hamish Innes and myself, “Runaway greenhouse on Hycean worlds.”
April 18, 2025 at 5:17 PM
The key climate modelling papers are my ApJ paper “Runaway Greenhouse on subNeptune water worlds,” and the paper by student Hamish Innes and myself, “Runaway greenhouse on Hycean worlds.”
There will be more discussion on the topic of subNeptune magma oceans at our subNeptune session at AbSciCon2026. The abstract deadline for that is closed, and we will soon be putting together the programme. BTW, very proud of the involvement of Oxford group postdoc Claire Guimond, ...
Another cool result shared at #RockyWorlds4: Nearly all sub-Neptunes, if they are gas dwarfs (as opposed to water worlds), should have magma oceans beneath their hydrogen atmospheres.
That includes the notorious K2-18b — if it is indeed a gas dwarf and not an ocean planet.
Preprint:
That includes the notorious K2-18b — if it is indeed a gas dwarf and not an ocean planet.
Preprint:
Most Rocky Sub-Neptunes are Molten: Mapping the Solidification Shoreline for Gas Dwarf Exoplanets
Sub-Neptunes are the most common type of detected exoplanet, yet their observed masses and radii are degenerate with several interior structures. One possibility is that sub-Neptunes have silicate/iro...
arxiv.org
January 20, 2026 at 3:15 PM
There will be more discussion on the topic of subNeptune magma oceans at our subNeptune session at AbSciCon2026. The abstract deadline for that is closed, and we will soon be putting together the programme. BTW, very proud of the involvement of Oxford group postdoc Claire Guimond, ...
(I'm actually hotter on the concept of life on subneptunes than on "Hyceans", even - the existence of a high pressure ice layer under a global ocean should render that ocean chemically inert and uninhabitable, but a subneptune would have circulation with its core)
April 17, 2025 at 1:31 PM
(I'm actually hotter on the concept of life on subneptunes than on "Hyceans", even - the existence of a high pressure ice layer under a global ocean should render that ocean chemically inert and uninhabitable, but a subneptune would have circulation with its core)
Guest post from Kennedi White: There’s a puzzling gap in the distribution of exoplanet sizes. Today’s paper explores the role of photo-evaporation and core composition on the formation of the radius valley. ⚛️ 🔭 ☄️ 🧪
astrobites.org/2026/06/11/subneptune-superearth/
astrobites.org/2026/06/11/subneptune-superearth/
[Guest post] The Secret Life of sub-Neptunes and super-Earths
There's a puzzling gap in the distribution of exoplanet sizes. Today's paper explores the role of photoevaporation and core composition on the formation of the radius valley.
astrobites.org
June 12, 2026 at 4:12 AM
Guest post from Kennedi White: There’s a puzzling gap in the distribution of exoplanet sizes. Today’s paper explores the role of photo-evaporation and core composition on the formation of the radius valley. ⚛️ 🔭 ☄️ 🧪
astrobites.org/2026/06/11/subneptune-superearth/
astrobites.org/2026/06/11/subneptune-superearth/
We knew K2-18b was extremely unlikly to support a liquid water ocean. That was made pretty clear in my subNeptune runaway paper, and made even clearer by Hamish Innes' paper on bringing H2+H2O into the picture. But there can be "waterworlds" without liquid water -- they can have layers of
September 19, 2025 at 7:17 PM
We knew K2-18b was extremely unlikly to support a liquid water ocean. That was made pretty clear in my subNeptune runaway paper, and made even clearer by Hamish Innes' paper on bringing H2+H2O into the picture. But there can be "waterworlds" without liquid water -- they can have layers of
Namrah Habib (from the Oxford exoplanet group, and one of my former DPhil students) is giving a very interesting talk on episodic convection in H2-rich subNeptune atmospheres.
July 7, 2025 at 5:29 PM
Namrah Habib (from the Oxford exoplanet group, and one of my former DPhil students) is giving a very interesting talk on episodic convection in H2-rich subNeptune atmospheres.
The most likely state of K2-18b is either a water-rich interior with the water in a hot supercritical state (as I wrote about in my papers, and as we also wrote about for the subNeptune TOI 270d) or a “gas dwarf” state
April 18, 2025 at 5:17 PM
The most likely state of K2-18b is either a water-rich interior with the water in a hot supercritical state (as I wrote about in my papers, and as we also wrote about for the subNeptune TOI 270d) or a “gas dwarf” state
I'd love to see this work presented at our AbSciCon subNeptune session.
Published in #MNRAS: "Redefining interiors and envelopes: hydrogen–silicate miscibility and its consequences for the structure and evolution of sub-Neptunes", Rogers et al. This is Fig. 2: for the caption & to read the paper please visit academic.oup.com/mnras/articl...
December 5, 2025 at 3:46 PM
I'd love to see this work presented at our AbSciCon subNeptune session.
Nice write-up of our work on subNeptune L 98-59 d. The work was led by (then) PCD group doctoral student Harrison Nicholls. A great team of authors I always enjoy working with.
From Flavia Pascal: In this Astrobite, we explore how L 98-59 d’s atmosphere and interior models reveal a molten world still being reshaped by its host star. ⚛️ 🔭 ☄️ 🧪
astrobites.org/2026/05/07/unwinding-exoplanetary-clocks/
astrobites.org/2026/05/07/unwinding-exoplanetary-clocks/
Rewinding exoplanetary clocks: L 98-59 d opens up research into a new type of molten worlds
We cannot travel back in time, but we can still try to reconstruct how planets evolved from the clues they leave behind today. In this Astrobite, we explore how L 98-59 d’s atmosphere and interior mod...
astrobites.org
May 8, 2026 at 4:11 AM
Nice write-up of our work on subNeptune L 98-59 d. The work was led by (then) PCD group doctoral student Harrison Nicholls. A great team of authors I always enjoy working with.
It would be so comforting at this point, to find life existing and evolving somewhere else in the universe.
To know that our screw-ups have not ruined everything everywhere forever.
#NASA #Life #Planets #SubNeptune #Universe
To know that our screw-ups have not ruined everything everywhere forever.
#NASA #Life #Planets #SubNeptune #Universe
This is K2-18b, a potentially habitable planet covered with oceans and about 2.6 times the size of Earth.
JWST has just detected carbon dioxide and methane in its atmosphere which can only be produced by living beings.
#LifeInTheUniverse
JWST has just detected carbon dioxide and methane in its atmosphere which can only be produced by living beings.
#LifeInTheUniverse
June 18, 2024 at 3:55 PM
It would be so comforting at this point, to find life existing and evolving somewhere else in the universe.
To know that our screw-ups have not ruined everything everywhere forever.
#NASA #Life #Planets #SubNeptune #Universe
To know that our screw-ups have not ruined everything everywhere forever.
#NASA #Life #Planets #SubNeptune #Universe
At #ExoclimesVI, Chloe Fisher (Oxford postdoc) is talking about using multi-planet subNeptune systems to explore subNeptune atmospheric chemistry. Notes that with NIRSPEC data only it is hard to get confident molecular features. NIRISS helps out a lot.
July 10, 2025 at 9:05 PM
At #ExoclimesVI, Chloe Fisher (Oxford postdoc) is talking about using multi-planet subNeptune systems to explore subNeptune atmospheric chemistry. Notes that with NIRSPEC data only it is hard to get confident molecular features. NIRISS helps out a lot.
This adds to the already abundant evidence that K2-18b (the currently coldest subNeptune characterized) does not have a habitable ocean, or indeed a liquid ocean of any sort.
September 10, 2025 at 9:30 AM
This adds to the already abundant evidence that K2-18b (the currently coldest subNeptune characterized) does not have a habitable ocean, or indeed a liquid ocean of any sort.
At #ExoclimesVII @nplinnspace.bsky.social is talking about HR observations of WASP-107b, a cloudy warm (700K) "subNeptune-like" planet. (Actually a borderline warm Jupiter). VLT/CRIRES+ observations. Interesting remarks on the effect of clouds on HR methodology
July 8, 2025 at 5:18 PM
At #ExoclimesVII @nplinnspace.bsky.social is talking about HR observations of WASP-107b, a cloudy warm (700K) "subNeptune-like" planet. (Actually a borderline warm Jupiter). VLT/CRIRES+ observations. Interesting remarks on the effect of clouds on HR methodology
Another exciting aspect of ARIEL is that it is better suited for studying #exoplanets around bright stars like 55 CancriA, and should inform us more about the enigmatic 55CancriA-e, which I'm beginning to think of as more like a hot subNeptune (being underdense) than a classic lava world.
August 15, 2025 at 9:17 AM
Another exciting aspect of ARIEL is that it is better suited for studying #exoplanets around bright stars like 55 CancriA, and should inform us more about the enigmatic 55CancriA-e, which I'm beginning to think of as more like a hot subNeptune (being underdense) than a classic lava world.
Why are exoplanets with around 2 Earth radii relatively rare? Simulations by scientists from MPIA, @unibern.bsky.social, and Geneva University found migrating icy planets to play a key role in explaining this phenomenon. #waterworld #astronomy #subneptune 🔭
www.mpia.de/news/science...
www.mpia.de/news/science...
Migration solves exoplanet puzzle
Simulations of planetary migration provide a possible explanation for the mysterious gap in the size distribution of super-Earths.
www.mpia.de
February 9, 2024 at 10:59 AM
Why are exoplanets with around 2 Earth radii relatively rare? Simulations by scientists from MPIA, @unibern.bsky.social, and Geneva University found migrating icy planets to play a key role in explaining this phenomenon. #waterworld #astronomy #subneptune 🔭
www.mpia.de/news/science...
www.mpia.de/news/science...
Double yikes! Even one more bare rock rocky #exoplanet . It's getting to be a pattern. Around low mass stars, either you're a subNeptune or a bare rock.
August 20, 2025 at 7:48 PM
Double yikes! Even one more bare rock rocky #exoplanet . It's getting to be a pattern. Around low mass stars, either you're a subNeptune or a bare rock.
#EPSCDPS2025 : One big takeaway from Yami's talk is that putting a volatile layer over a magma ocean greatly increases partial pressure of rock vapours (mostly via oxygen reactions). Results presented are only up to roughly 10 bars though, so not subNeptune like. More work!
September 12, 2025 at 6:54 AM
#EPSCDPS2025 : One big takeaway from Yami's talk is that putting a volatile layer over a magma ocean greatly increases partial pressure of rock vapours (mostly via oxygen reactions). Results presented are only up to roughly 10 bars though, so not subNeptune like. More work!
And from the remote shores of MIT, I had the pleasure of tuning in to Dr. Rogers' talk. Bringing supercritical silicates into the picture for subNeptune evolution modeling is a big advance. It's clear, though, that we need more thermodynamics and opacity data to really pin this down.
June 11, 2026 at 1:17 PM
And from the remote shores of MIT, I had the pleasure of tuning in to Dr. Rogers' talk. Bringing supercritical silicates into the picture for subNeptune evolution modeling is a big advance. It's clear, though, that we need more thermodynamics and opacity data to really pin this down.
#EPSCDPS2025 Paul Byrne gave many important insights about the history of volcanism in the Solar system, but had one slide that was off the mark, in which he put the subNeptune TOI 270d on the same slide as Europa, tagging it as a "hycean world" with a subsurface open.
September 11, 2025 at 6:53 AM
#EPSCDPS2025 Paul Byrne gave many important insights about the history of volcanism in the Solar system, but had one slide that was off the mark, in which he put the subNeptune TOI 270d on the same slide as Europa, tagging it as a "hycean world" with a subsurface open.
Now even for rocky planets this would only be in the habitable zone under very optimistic conditions, as its equilibrium temperature is 330K, even assuming a 30% albedo. That's generally enough to trigger a runaway greenhouse, a threshold which is relevant to a water-dominated subNeptune as well,
October 6, 2025 at 3:51 PM
Now even for rocky planets this would only be in the habitable zone under very optimistic conditions, as its equilibrium temperature is 330K, even assuming a 30% albedo. That's generally enough to trigger a runaway greenhouse, a threshold which is relevant to a water-dominated subNeptune as well,
"Subneptune" means exactly what it sounds like - a planet that is like Neptune in composition but much, much smaller (in this case only about twice the radius of Earth)
April 17, 2025 at 1:06 PM
"Subneptune" means exactly what it sounds like - a planet that is like Neptune in composition but much, much smaller (in this case only about twice the radius of Earth)