Astronomers say they’ve found “the most promising signs yet” of chemicals on a planet beyond our Solar System that could indicate the presence of life on its surface.
Using the James Webb Space Telescope, the team found a possible ‘biosignature’ – the potential fingerprint of life – within its atmosphere, although they say they’re remaining “cautious”, and that this isn’t a confirmed detection.
The chemicals detected are the same as those produced by marine-dwelling organisms on Earth.
The team, led by the University of Cambridge in the UK, detected signs of dimethyl sulfide and dimethyl disulfide in the atmosphere of exoplanet K2-18b.
This planet orbits its star in the habitable zone (sometimes called the Goldilocks Zone), which is the region around a star in which an orbiting planet might have conditions suitable for the emergence of life, such as the ability for liquid water to exist on its surface.
K2-18b is 8.6 times as massive and 2.6 times as large as Earth and lies 124 lightyears away from our planet.
Building a bigger picture
This isn’t the first study of exoplanet K2-18b.
A 2023 study of K2-18b by the same team identified methane and carbon dioxide in the planet’s atmosphere.
This in itself was a huge discovery: the first time carbon-based molecules had been found in the atmosphere of an exoplanet – a planet beyond our Solar System – in the habitable zone.
Astronomers say the 2023 results showed K2-18b could be a ‘Hycean’ planet, meaning a habitable world with a liquid ocean and a hydrogen-rich atmosphere.
That earlier study found a tantalising hint of dimethyl sulfide and dimethyl disulfide, but this latest study has made a more promising detection.
“We didn’t know for sure whether the signal we saw last time was due to DMS, but just the hint of it was exciting enough for us to have another look with JWST using a different instrument,” says Professor Nikku Madhusudhan from Cambridge’s Institute of Astronomy, who led the research.
The team say that on Earth, dimethyl sulfide and dimethyl disulfide are only produced by life, mainly microbial life like phytoplankton we see in our oceans.
However, there could be another explanation for the detection of the chemical.
Another unknown chemical process could be the source of the molecules detected in K2-18b’s atmosphere.
Nevertheless, the team say “the results are the “strongest evidence yet” that life may
17 Comments
throwaway290
TL;DR
– K2-18b
– detected dimethyl sulfide and dimethyl disulfide, false positive possibility is now very low
– "produced by marine-dwelling organisms on Earth", possibility they were produced by other processes (unrelated to life as we know it) not high but maybe unknown unknowns
– other factors like distance from the star are in favor of life & water
– previous studies detected methane and carbon dioxide
ZiiS
Astronomers have yet again found possible signs of alien life.
weberer
Here's the primary source
https://iopscience.iop.org/article/10.3847/2041-8213/adc1c8
They possibly detected dimethyl sulfide, which is only known to be produced by living organisms.
seanhunter
Firstly that is completely badass science. The idea that you can use observations to detect the chemical composition of an exoplanet millions of kilometres away is an absolute triumph of the work of thousands of people over hundreds of years. Really amazing and deeply humbling to me.
Secondly, my prior was always that life existed outside of earth. It just seems so unlikely that we are somehow that special. If life developed here I always felt it overwhelmingly likely that it developed elsewhere too given how incredibly unfathomably vast the universe is.
sph
A bit clickbaity of OP to skip the operative word ‘promising’ signs of life.
eecc
JSWT… again the most formidable piece of equipment ever shot into outer space. That think is going to shake our understanding of the Universe to its foundations a couple times around
londons_explore
This is happening 124 light years away from earth.
That means if we develop a way to make a space ship accelerate at 1g for a long period of time, you could go there in just 10 relativistic years.
Unfortunately, whilst science allows such a rocket, our engineering skills are far from being able to build one.
tomelders
My understanding is that the great filter theory means this is bad news for us humans here on earth. And considering the state of the world right now, it's especially ominous. Fate loves irony.
MrPapz
Maybe now we can stop this nonsense of competing among each other and start dedicating efforts to an international space program.
cdplayer96
Here's to hoping we can learn more about this. But I feel like this could be caused by us simply not understanding how dimethyl sulfide can be formed on other planets, especially ones over 100 lightyears away..
what-the-grump
What am I missing here?
This claims that we can detect farts (sewer odor) a trillion miles away and it’s a sign of life?
This is an amazing troll post?
GenshoTikamura
That literally smells fishy
milesrout
Is there a source for this that isn't plastered with banner ads? I can't read more than a sentence at a time without having to scroll past adverts.
I do wonder why I was stupid enough to pay for a phone with a bigger screen as it just seems to mean more and bigger ads on screen at once and the same amount of content.
tjpnz
How far off are we from being able to image an exoplanet?
davedx
Some speculation
On DMS:
– DMS is a very specific configuration that’s rarely the endpoint of non-living chemical cycles.
– The simplicity of DMS doesn’t make it less indicative of life—it actually makes it a very selective molecule, which only shows up in large quantities when life is involved (at least in Earth-like chemistry).
– Until we find a compelling abiotic pathway, high DMS remains a strong biosignature, especially in the context of a planet with a potential ocean and mild temperatures
Possible origins:
We’re looking at some form of life that can:
– Thrive in a hydrogen-rich atmosphere
– Possibly live in or on top of a global ocean
– Generate large amounts of DMS—potentially thousands of times more than Earth
The closest Earth analogy is:
– Marine phytoplankton, particularly species like Emiliania huxleyi, produce DMS as a byproduct of breaking down DMSP, a molecule they use to regulate osmotic pressure and protect against oxidative stress.
– If something similar is happening on K2-18 b, we’d be talking about an ocean teeming with such microbes—perhaps far denser than Earth’s oceans.
Possibly "Giant photosynthetic mats" or sulfuric "algae"
If there’s some landmass or floating structures, maybe the DMS producers are:
– Photosynthetic, sulfur-metabolizing analogues to cyanobacteria
– Living in dense floating colonies or mats like microbial reefs
– Using dimethylated sulfur compounds in their metabolism, and leaking DMS as waste or signaling molecules
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Of course there have been lots of ocean planets in sci-fi literature, but I'm most reminded of the "Pattern Juggler" Planet Ararat from Alastair Reynolds' "Revelation Space" series.
This is incredibly exciting news!
jmyeet
Earlier discussion: https://news.ycombinator.com/item?id=43711376
Xiol32
Editorialized headline. Article is:
> Astronomers have found the 'most promising signs yet' of alien life on a planet beyond our Solar System