Paul Byrne
@theplanetaryguy.bsky.social
Associate Professor of Earth, Environmental, and Planetary Science at Washington University in St. Louis • Planetary Data System Geosciences Node Director • Planetary Bastard • he/him/Sir
See that larger white blob at lower left, and the smaller blob to its right?
That's Earth and the Moon.
Photographed from the orbit of Mercury.
That's Earth and the Moon.
Photographed from the orbit of Mercury.
January 15, 2026 at 2:45 AM
See that larger white blob at lower left, and the smaller blob to its right?
That's Earth and the Moon.
Photographed from the orbit of Mercury.
That's Earth and the Moon.
Photographed from the orbit of Mercury.
Psst.
This is a lightning bolt.
On fucking Jupiter.
This is a lightning bolt.
On fucking Jupiter.
January 14, 2026 at 1:55 AM
Psst.
This is a lightning bolt.
On fucking Jupiter.
This is a lightning bolt.
On fucking Jupiter.
Saturn and its rings.
January 13, 2026 at 3:35 AM
Saturn and its rings.
Here's some ice I can get behind.
The southern polar cap of Mars, imaged by ESA's Mars Express spacecraft in December 2012.
Much of this ice is frozen CO₂, with some portion of conventional (to us) water ice, too.
The southern polar cap of Mars, imaged by ESA's Mars Express spacecraft in December 2012.
Much of this ice is frozen CO₂, with some portion of conventional (to us) water ice, too.
January 10, 2026 at 11:33 PM
Here's some ice I can get behind.
The southern polar cap of Mars, imaged by ESA's Mars Express spacecraft in December 2012.
Much of this ice is frozen CO₂, with some portion of conventional (to us) water ice, too.
The southern polar cap of Mars, imaged by ESA's Mars Express spacecraft in December 2012.
Much of this ice is frozen CO₂, with some portion of conventional (to us) water ice, too.
The same amount of time has now elapsed between when Raiders of the Lost Ark was released (1981) and when it was set (1936) as when it was released and today (45 years).
I find this... offensive.
I find this... offensive.
January 10, 2026 at 2:52 AM
The same amount of time has now elapsed between when Raiders of the Lost Ark was released (1981) and when it was set (1936) as when it was released and today (45 years).
I find this... offensive.
I find this... offensive.
For those of you what like graphs, here's a plot of total (absolute) numbers of abstracts versus year since 2021 to now. (There was no LPSC in 2020 on account of COVID-19, and I can't be bothered to go back to 2019 or beyond because it's late and I'm tired.)
January 9, 2026 at 6:29 AM
For those of you what like graphs, here's a plot of total (absolute) numbers of abstracts versus year since 2021 to now. (There was no LPSC in 2020 on account of COVID-19, and I can't be bothered to go back to 2019 or beyond because it's late and I'm tired.)
I submitted an abstract to LPSC 2026.
I wanted to see how many abstracts were submitted this year. Mine went in at 11:58 pm Central, so is among the last to go in. It will be rejected, but for the student rate ($35) it was worth the experiment.
(1/2)
I wanted to see how many abstracts were submitted this year. Mine went in at 11:58 pm Central, so is among the last to go in. It will be rejected, but for the student rate ($35) it was worth the experiment.
(1/2)
January 9, 2026 at 6:03 AM
I submitted an abstract to LPSC 2026.
I wanted to see how many abstracts were submitted this year. Mine went in at 11:58 pm Central, so is among the last to go in. It will be rejected, but for the student rate ($35) it was worth the experiment.
(1/2)
I wanted to see how many abstracts were submitted this year. Mine went in at 11:58 pm Central, so is among the last to go in. It will be rejected, but for the student rate ($35) it was worth the experiment.
(1/2)
Here's a small timeline cleanse.
This is part of a much larger deep-field image from #JWST, and shows just how absurdly big the Universe is.
It's a tiny part of the Boötes constellation, about 2.4 arc minutes across. Every six-sided feature is a star in the Milky Way.
Everything else is a galaxy.
This is part of a much larger deep-field image from #JWST, and shows just how absurdly big the Universe is.
It's a tiny part of the Boötes constellation, about 2.4 arc minutes across. Every six-sided feature is a star in the Milky Way.
Everything else is a galaxy.
January 7, 2026 at 11:43 PM
Here's a small timeline cleanse.
This is part of a much larger deep-field image from #JWST, and shows just how absurdly big the Universe is.
It's a tiny part of the Boötes constellation, about 2.4 arc minutes across. Every six-sided feature is a star in the Milky Way.
Everything else is a galaxy.
This is part of a much larger deep-field image from #JWST, and shows just how absurdly big the Universe is.
It's a tiny part of the Boötes constellation, about 2.4 arc minutes across. Every six-sided feature is a star in the Milky Way.
Everything else is a galaxy.
We analysed *modern* Europa.
It may have been subject to MUCH more tidal heating at some point in the distant past. If so, there could have been a lot more tectonic activity on the seafloor, at least temporarily.
But it might also mean Europa's seafloor, today... is an alien graveyard.
(10/n)
It may have been subject to MUCH more tidal heating at some point in the distant past. If so, there could have been a lot more tectonic activity on the seafloor, at least temporarily.
But it might also mean Europa's seafloor, today... is an alien graveyard.
(10/n)
January 6, 2026 at 6:53 PM
We analysed *modern* Europa.
It may have been subject to MUCH more tidal heating at some point in the distant past. If so, there could have been a lot more tectonic activity on the seafloor, at least temporarily.
But it might also mean Europa's seafloor, today... is an alien graveyard.
(10/n)
It may have been subject to MUCH more tidal heating at some point in the distant past. If so, there could have been a lot more tectonic activity on the seafloor, at least temporarily.
But it might also mean Europa's seafloor, today... is an alien graveyard.
(10/n)
We then calculated what *stresses* these weak, fractured seafloor rocks could be subject to that would allow those fractures to move to expose fresh rock.
Turns out tides don't do it.
Interior cooling won't do it.
And mantle convection won't do it. No plate tectonics within Europa!
(7/n)
Turns out tides don't do it.
Interior cooling won't do it.
And mantle convection won't do it. No plate tectonics within Europa!
(7/n)
January 6, 2026 at 6:34 PM
We then calculated what *stresses* these weak, fractured seafloor rocks could be subject to that would allow those fractures to move to expose fresh rock.
Turns out tides don't do it.
Interior cooling won't do it.
And mantle convection won't do it. No plate tectonics within Europa!
(7/n)
Turns out tides don't do it.
Interior cooling won't do it.
And mantle convection won't do it. No plate tectonics within Europa!
(7/n)
WAAAAIT A MINUTE I hear you say
Water makes rock weak. And these rocks are *surely* saturated.
You're right, they are!
In fact, we *intentionally* consider rocks that are wet, have pores filled with water, and are in fact already fractured.
We WANT fractures to slip and expose fresh rock!
(6/n)
Water makes rock weak. And these rocks are *surely* saturated.
You're right, they are!
In fact, we *intentionally* consider rocks that are wet, have pores filled with water, and are in fact already fractured.
We WANT fractures to slip and expose fresh rock!
(6/n)
January 6, 2026 at 6:24 PM
WAAAAIT A MINUTE I hear you say
Water makes rock weak. And these rocks are *surely* saturated.
You're right, they are!
In fact, we *intentionally* consider rocks that are wet, have pores filled with water, and are in fact already fractured.
We WANT fractures to slip and expose fresh rock!
(6/n)
Water makes rock weak. And these rocks are *surely* saturated.
You're right, they are!
In fact, we *intentionally* consider rocks that are wet, have pores filled with water, and are in fact already fractured.
We WANT fractures to slip and expose fresh rock!
(6/n)
We figured out how strong the ocean floor is, and how that strength increases as you go deeper into the body.
The blue and magenta lines mark out the strength of the (sub)seafloor rocks if you wanted to make normal or thrust fault, respectively.
Turns out these rocks are fairly strong.
(5/n)
The blue and magenta lines mark out the strength of the (sub)seafloor rocks if you wanted to make normal or thrust fault, respectively.
Turns out these rocks are fairly strong.
(5/n)
January 6, 2026 at 6:19 PM
We figured out how strong the ocean floor is, and how that strength increases as you go deeper into the body.
The blue and magenta lines mark out the strength of the (sub)seafloor rocks if you wanted to make normal or thrust fault, respectively.
Turns out these rocks are fairly strong.
(5/n)
The blue and magenta lines mark out the strength of the (sub)seafloor rocks if you wanted to make normal or thrust fault, respectively.
Turns out these rocks are fairly strong.
(5/n)
So we ran calculations widely used for rocks on Earth to figure out how strong the ocean floor might be, remembering that most of Europa is rock!
Why?
Because fractures are a GREAT way of exposing fresh rock to the ocean, driving chemical reactions for life.
No fractures? No fresh rock.
(4/n)
Why?
Because fractures are a GREAT way of exposing fresh rock to the ocean, driving chemical reactions for life.
No fractures? No fresh rock.
(4/n)
January 6, 2026 at 6:13 PM
So we ran calculations widely used for rocks on Earth to figure out how strong the ocean floor might be, remembering that most of Europa is rock!
Why?
Because fractures are a GREAT way of exposing fresh rock to the ocean, driving chemical reactions for life.
No fractures? No fresh rock.
(4/n)
Why?
Because fractures are a GREAT way of exposing fresh rock to the ocean, driving chemical reactions for life.
No fractures? No fresh rock.
(4/n)
The original science question my co-author Christian and I asked was simply:
What does the seafloor of Europa actually *look* like?
This question came about because, although we can see Europa's icy exterior pretty well, we know virtually nothing of its interior.
(3/n)
What does the seafloor of Europa actually *look* like?
This question came about because, although we can see Europa's icy exterior pretty well, we know virtually nothing of its interior.
(3/n)
January 6, 2026 at 6:06 PM
The original science question my co-author Christian and I asked was simply:
What does the seafloor of Europa actually *look* like?
This question came about because, although we can see Europa's icy exterior pretty well, we know virtually nothing of its interior.
(3/n)
What does the seafloor of Europa actually *look* like?
This question came about because, although we can see Europa's icy exterior pretty well, we know virtually nothing of its interior.
(3/n)
Our paper, "Little to no active faulting likely at Europa’s
seafloor today", was just published today in Nature Communications!
This version of the paper was submitted early last year and accepted in November, but the genesis of this paper started a VERY long time ago (relatively speaking)
(2/n)
seafloor today", was just published today in Nature Communications!
This version of the paper was submitted early last year and accepted in November, but the genesis of this paper started a VERY long time ago (relatively speaking)
(2/n)
January 6, 2026 at 6:02 PM
Our paper, "Little to no active faulting likely at Europa’s
seafloor today", was just published today in Nature Communications!
This version of the paper was submitted early last year and accepted in November, but the genesis of this paper started a VERY long time ago (relatively speaking)
(2/n)
seafloor today", was just published today in Nature Communications!
This version of the paper was submitted early last year and accepted in November, but the genesis of this paper started a VERY long time ago (relatively speaking)
(2/n)
New paper alert!
tl;dr: the seafloor of Europa is probably tectonically inert, meaning little to no active fracturing that could expose fresh rock to seawater.
Without such water–rock reactions the prospect for there being life within Europa just took a big hit.
A thread:
tl;dr: the seafloor of Europa is probably tectonically inert, meaning little to no active fracturing that could expose fresh rock to seawater.
Without such water–rock reactions the prospect for there being life within Europa just took a big hit.
A thread:
January 6, 2026 at 5:55 PM
New paper alert!
tl;dr: the seafloor of Europa is probably tectonically inert, meaning little to no active fracturing that could expose fresh rock to seawater.
Without such water–rock reactions the prospect for there being life within Europa just took a big hit.
A thread:
tl;dr: the seafloor of Europa is probably tectonically inert, meaning little to no active fracturing that could expose fresh rock to seawater.
Without such water–rock reactions the prospect for there being life within Europa just took a big hit.
A thread:
This is one of my favourite space pictures.
Crescent Earth, photographed by the crew of Apollo 15.
Crescent Earth, photographed by the crew of Apollo 15.
January 5, 2026 at 11:17 PM
This is one of my favourite space pictures.
Crescent Earth, photographed by the crew of Apollo 15.
Crescent Earth, photographed by the crew of Apollo 15.
This is one amazing photo.
Jets of water vapour and ice crystals blasting out through four deep fractures in the icy shell of Saturn's tiny moon Enceladus.
This is the only alien ocean we know of that we can directly access.
(1/2)
Jets of water vapour and ice crystals blasting out through four deep fractures in the icy shell of Saturn's tiny moon Enceladus.
This is the only alien ocean we know of that we can directly access.
(1/2)
January 4, 2026 at 10:02 PM
This is one amazing photo.
Jets of water vapour and ice crystals blasting out through four deep fractures in the icy shell of Saturn's tiny moon Enceladus.
This is the only alien ocean we know of that we can directly access.
(1/2)
Jets of water vapour and ice crystals blasting out through four deep fractures in the icy shell of Saturn's tiny moon Enceladus.
This is the only alien ocean we know of that we can directly access.
(1/2)
Conamara Chaos is labelled here on Europa (shown in pink).
January 1, 2026 at 10:41 PM
Conamara Chaos is labelled here on Europa (shown in pink).
There's an area on Jupiter's icy moon called Conamara Chaos, a region of disrupted crust thought to form from meltwater within the ice shell.
It's named for Conamara in County Galway, Ireland—a beautiful if desolate part of the world, and somewhere I visited today.
It's named for Conamara in County Galway, Ireland—a beautiful if desolate part of the world, and somewhere I visited today.
January 1, 2026 at 10:19 PM
There's an area on Jupiter's icy moon called Conamara Chaos, a region of disrupted crust thought to form from meltwater within the ice shell.
It's named for Conamara in County Galway, Ireland—a beautiful if desolate part of the world, and somewhere I visited today.
It's named for Conamara in County Galway, Ireland—a beautiful if desolate part of the world, and somewhere I visited today.
On 13 February 1990, from a distance of 6.4 billion km, NASA's Voyager 1 spacecraft turned around and photographed our homeworld.
About halfway up on the right side is a tiny speck of light, about one pixel across.
"That's home. That's us.
A mote of dust suspended in a sunbeam."
—Carl Sagan
About halfway up on the right side is a tiny speck of light, about one pixel across.
"That's home. That's us.
A mote of dust suspended in a sunbeam."
—Carl Sagan
December 31, 2025 at 11:17 PM
On 13 February 1990, from a distance of 6.4 billion km, NASA's Voyager 1 spacecraft turned around and photographed our homeworld.
About halfway up on the right side is a tiny speck of light, about one pixel across.
"That's home. That's us.
A mote of dust suspended in a sunbeam."
—Carl Sagan
About halfway up on the right side is a tiny speck of light, about one pixel across.
"That's home. That's us.
A mote of dust suspended in a sunbeam."
—Carl Sagan
The Sun has set on 2025*
*at least here in western Mayo
*at least here in western Mayo
December 31, 2025 at 4:51 PM
The Sun has set on 2025*
*at least here in western Mayo
*at least here in western Mayo