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Webb Discovers Methane, Carbon Dioxide in Atmosphere of K2-18B
- sgt101 3y agoGosh - imagine that place! I wonder how old this world is, and how stable its enviroment is/has been. Complex animal life took 3.5 bn years to emerge on Earth, of course that's a meaningless data point by itself but intuitively for this place to have an ecosystem or complex life it needs to be old. Still, even without this what a wonderful and weird environment.
- unsupp0rted 3y ago> Complex animal life took 3.5 bn years to emerge on Earth, How certain are we it took that long (the first time)?
- tracedddd 3y agoNot certain at all, it’s based on last universal common ancestor estimates(LUCA) and supported by (lack of) fossil record.
- wolverine876 3y ago> it’s based on last universal common ancestor estimates(LUCA) and supported by (lack of) fossil record. I thought the Cambrian Explosion's fossil record was pretty sizeable - in fact, it's named after the place where the fossil layer was first discovered. I didn't know it was related to a common ancestor. Are you thinking of something else or am I missing something major?
- edgyquant 3y agoYes but we’re talking about before the Cambrian
- wolverine876 3y ago? >>> Complex animal life took 3.5 bn years to emerge on Earth, >> How certain are we it took that long (the first time)? > Not certain at all, it’s based on last universal common ancestor estimates(LUCA) and supported by (lack of) fossil record. Do you mean, there's little evidence of pre-Cambrian absence? Absence of evidence is some evidence of absence, in this case. But how does LUCA fit into this question?
- sgt101 3y agoI think we can see where different complex animals split in their evolutionary tree - so humans and starfish split a long way back. Then we use a standard mutation clock to estimate how long ago that was. If all complex animals split from simple animals an estimated 700m years ago...
- no_wizard 3y agoIts possible there is a good explanation for why there would be no strong fossil record[0] for an advanced civilization preceding us. >When it comes to direct evidence of an industrial civilization—things like cities, factories, and roads—the geologic record doesn’t go back past what’s called the Quaternary period 2.6 million years ago. For example, the oldest large-scale stretch of ancient surface lies in the Negev Desert. It’s “just” 1.8 million years old—older surfaces are mostly visible in cross section via something like a cliff face or rock cuts. While I think its highly unlikely (I mean less than 0.00001% possible) the means in which we would could even detect it are complicated [0]: https://www.theatlantic.com/science/archive/2018/04/are-we-earths-only-civilization/557180/ https://www.theatlantic.com/science/archive/2018/04/are-we-e...
- delta_p_delta_x 3y agoThe fossil record. There is little evidence of very complex animal life before about 541 million years ago, which is when the Cambrian explosion begun.
- TheBlight 3y agoGiven the surface of the planet is such a dynamic environment, I wonder how much evidence we should expect even if it did exist. See also: https://www.scientificamerican.com/article/could-an-industrial-prehuman-civilization-have-existed-on-earth-before-ours/ https://www.scientificamerican.com/article/could-an-industri...
- Rebelgecko 3y agoThere's quite a few fossils showing single-celled organisms from 3+ billion years ago. I imagine if more complex life existed the fossils could've survived
- no_wizard 3y agoWhen you say very little, do you mean none, or there is some questionable evidence? I'm genuinely curious
- dudinax 3y agoBefore "modern" life evolved in the pre-cambrian era, there was the Ediacaran life forms that were complex multicellular life, but died out millions of years before the Cambrian explosion. https://en.wikipedia.org/wiki/Ediacaran_biota https://en.wikipedia.org/wiki/Ediacaran_biota
- svachalek 3y agoSingle cell life appeared on Earth almost instantly after the planet cooled down enough to allow it. I don't think it's clear that any progress was being made over the next few billion years. One day the right mutation happened and boom, fancy life everywhere. With our data sample of one, I don't think it's clear if it was extraordinarily bad luck it took that long to happen, or extraordinarily good luck it ever happened at all.
- fbdab103 3y agoEukaryotic cell is such a bonkers insane development, I definitely lean towards the impossibly lucky scenario. There was no need for that to be the origin story of a mitochondria like organelle (https://en.wikipedia.org/wiki/Symbiogenesis https://en.wikipedia.org/wiki/Symbiogenesis), but that's what we think we have. That being said, there was an experiment (https://www.pnas.org/doi/full/10.1073/pnas.1115323109 https://www.pnas.org/doi/full/10.1073/pnas.1115323109) which was able to select single cellular organisms to "become multicellular" in a rapid amount of time (<50 generations? been a while since I read it). Which says to me that, theoretically, the process is not hard, it just requires trillions of attemps to evoke something that works.
- kjkjadksj 3y agoIt not only has to work, the mutant has to have a fitness advantage over the nonmutant or it will drop out of the population before long. The vast majority of mutations are also “bad.”
- skywal_l 3y agoSeems to be down. This page seems to work: https://webbtelescope.org/contents/news-releases/2023/news-2023-139 https://webbtelescope.org/contents/news-releases/2023/news-2...
- bayesianbot 3y ago404 not found, did they maybe remove the article for some reason?
- wfurney 3y agohttps://web.archive.org/web/20230911143418/https://www.nasa.gov/goddard/2023/webb-discovers-methane-carbon-dioxide-in-atmosphere-of-k2-18b https://web.archive.org/web/20230911143418/https://www.nasa....
- ZunarJ5 3y agoThis feels like a big deal. The website seems to be getting hammered as it is working on and off.
- willis936 3y agoWhat makes it feel like a big deal? Carbon, oxygen, and hydrogen are extremely abundant. Those molecules are relatively low energy combinations of the elements. I would be surprised to not find them in the atmospheres of big rocky planets.
- bilekas 3y agoApperantly it seems to be the presence of " dimethyl sulfide ". It seemingly only produced, on earth at least, by life. So using us as a baseline it seems pretty interesting. > DMS is generated by the degradation of dimethylsulfoniopropionate, which is present in many species of marine algae and plants, including dinoflagellates and coccolithophores
- kaycebasques 3y agoIt's mind-bendingly cool that people can figure out the composition of an atmosphere without actually being close to that atmosphere. Had not heard of dimethyl sulfide before. That's a good keyword to know.
- julienchastang 3y agoFrom a single pixel of light! Indeed mind blowing.
- treyd 3y agoThat's somewhat misleading though. It's not really a pixel in that there's much more information available than, basically, 3 integers between 0 and 255. There's 4 instruments on the telescope that collect 4 different chunks of IR spectra, and there's very precise and granular intensity values for light received around any given wavelength. Much more detail than a "pixel" has in the typical sense we use them. It's not a lot of information, not nearly enough to identify surface features on an exoplanet, but it's very useful data if you're trying to identify likely chemical composition of bodies or how hot clouds of gas are.
- finite_depth 3y agoThis is an easier problem than it probably seems. Atmospheres are relatively low-density gas, which means they produce an absorption spectrum - a chemical fingerprint that identifies most atoms and molecules quite reliably. It's such a good fingerprint that it was used to discover several chemical elements, most notably helium (observed in the Sun's spectrum before it was known on Earth).
- cout 3y ago> These initial Webb observations also provided a possible detection of a molecule called dimethyl sulfide (DMS). On Earth, this is only produced by life. The bulk of the DMS in Earth’s atmosphere is emitted from phytoplankton in marine environments. Given a sufficient quantity of reactants/reagents, could DMS be produced via a natural process, or is this a sufficiently unfavorable reaction that it's unlikely?
- marcosdumay 3y agoI don't think anybody knows enough to tell you what kinds of reactions happen on planet-wide environments without an oxidizing atmosphere.
- kjkjadksj 3y agoChemist certainly do. Reactions are carried out at specific atmospheric conditions. E.g. oxygen may well be purged.
- marcosdumay 3y agoChemists do controlled reactions in controlled environments. It's a completely different thing from knowing what happens somewhere in a planet.
- kjkjadksj 3y agoIt is produced industrially without needing life. I’m not sure why its the alleged smoking gun if theoretically if the conditions are right and the reaction is catalyzed it will go on without needing a lifeform. 2 CH3OH + H2S → (CH3)2S + 2 H2O
- deleted 3y ago[deleted]
- v8xi 3y agoIn Nick Lane's Oxygen: The Molecule that Made the World, he talks about the importance of both methane and carbon dioxide and how they exist at the extremes of a complex metabolic oxidation-reduction cycle. Methane stores a lot of chemical energy in its C-H bonds which can be burned directly, or metabolized through repeat oxidation events to ultimately form CO2, which plants utilize with the help of the sun to form more CH bonds before ultimately breaking down into methane again. Hence, an exoplanet with both molecules in its atmosphere is a promising candidate in the search for life.
- julienchastang 3y agoThanks for the book recommendation. Added to reading list.
- behnamoh 3y agoI wonder what life looks like on a planet which is over 8 times more massive than the Earth. Do animals have spines at all on a planet with almost 8g gravity? Does life even get to evolve into complex systems like animals under this much gravity? How about plants? Do they grow up or spread out instead? If one day we get a visitor from this planet, they'll jump on our planet the same way human astronauts jumped on the Moon.
- dylan604 3y agoThe gravity question is one I've pondered myself as a thought exercise. There's been discussions on how far up a plant can draw water as the defining limit to how tall a tree could grow. Some discussions as well on how tall an animal could grow based on how high blood could be pumped up. Which is a direction different from the structural support and sizes that I find interesting.
- adriand 3y agoI can imagine an intelligent species on a high-G planet scratching their “heads” and wondering, as they surveil Earth, how anything could possibly survive on such a low-G planet.
- julienchastang 3y agoOn this topic, I just finished reading "A Very Short Introduction to Planetary Systems"[0] by Raymond T. Pierrehumbert. He devotes a good portion of the book to exoplanet atmospheres. It is one of the best science books I've read. Pierrehumbert really has a knack for explaining complex material clearly and concisely. I really recommend it. [0] https://global.oup.com/academic/product/planetary-systems-a-very-short-introduction-9780198841128?cc=us&lang=en& https://global.oup.com/academic/product/planetary-systems-a-...
- nickhalfasleep 3y agoScientists using Webb may be able to present some surprisingly strong evidence that we are not the only life bearing planet in the galaxy.
- jug 3y agoYeah, not sure about the sensitivity, if it's particularly good conditions here but at least this data set looks like it gives remarkably little room for false positives and quite highly detailed. I thought it would push JWST a bit harder but this looks promising. Even a novice can read out the evidence for various molecules in that graph? So, if only we'd find an exciting result soon!
- Jeff_Brown 3y agoIn case you wondered too, this is 124 light-years from us.
- Aachen 3y agoWow, that's really close so far as these things go. With the nearest star being 4ly, this can be reached with essentially the same tech level if we'd want to visit that with a rover or generational ship one day
- BoiledCabbage 3y agoWhat's also crazy is if we did send a rover over there to hunt for life, and they found it, we'd have to wait 125 years to hear the result. We all sit around knowing to listen to the skies sometime in October of 2185 to hear if the rover found life within the first month of its landing. If we ever send a team to live there, we'd hear broadcasts of their lives from 125 years prior. A real portal in time - so cool.
- polishdude20 3y ago2185? Not 2273?
- jandrese 3y agoEven worse if we are still limited by Newtonian dynamics it will take thousands of years for a probe to reach there. The rocket equation is a harsh mistress. In practical terms we will never visit that world without completely upending physics as we know it.
- holoduke 3y agoWe just need a 1g rocket. Will take only a few days to get there. Life on earth will be 1000 years ahead once we are back though.
- 3y ago
- lofaszvanitt 3y ago120 light years away. Time to get the ufo tech out already.
- 7373737373 3y agoUnfortunately humanity has not yet understood the potential that is out there, and is too busy fighting over the limited one here on Earth.
- no_wizard 3y agois Faster Than Light travel even possible? I'm asking in a serious way. I have always read that its impossible, at least within our current knowledge. the only semi-plausible theory I've ever heard is that Blackholes might one day yield some way of traveling quickly across the universe but nobody has shown anything substantiated around that or anything else.
- svachalek 3y agoThere's no realistically plausible solution I've ever heard of, that is, ones that don't require millions of years of setup and entire stars worth of energy production. But that's with our current understanding of physics. While our current models seem nearly perfect and therefore nearly complete, there was a time they thought that about Newtonian physics. Perhaps some detail we need to understand dark matter or dark energy could spring the whole field wide open again.
- edgyquant 3y ago> While our current models seem nearly perfect and therefore nearly complete I’m not sure this is the case. Basically every physicist I’ve met thinks we’re in for another general relativity and that a unified theory will be a lot different than the multitude of theories we have now
- midoridensha 3y ago>While our current models seem nearly perfect and therefore nearly complete Huh? Where did you get this idea? Our physics is clearly nowhere near complete. Quantum Mechanics and General Relativity are at odds, which is why physicists have been looking for a unified theory for ages. Each one only works at certain scales, and not at the other end, so obviously something's wrong with them. The whole "dark matter" thing looks like BS too, and alternate theories like MOND don't require it. There's nothing complete at all about our understanding of physics.
- CodeL 3y ago[flagged]
- swader999 3y agoNice to know we aren't the only ones struggling with CO2.
- jncfhnb 3y agoSuppose a planet like this had non intelligent megafauna life. How could we detect this?
- dudinax 3y agoOne way is to build bigger telescopes and hope its not too cloudy.
- floxy 3y ago"Direct Imaging of an Exoplanet with a Solar Gravity Lens (1 Km Resolution)": https://arxiv.org/abs/1802.08421 https://arxiv.org/abs/1802.08421 ...and an excellent video on the topic: https://www.youtube.com/watch?v=NQFqDKRAROI https://www.youtube.com/watch?v=NQFqDKRAROI
- deleted 3y ago[deleted]
- nofitty376 3y agoThat spectrum is so noisy. How can they infer the blue fit from the (noisy) white points? The data look almost consistent with flat (no detection). And even if there is a detection, it looks like many other models could potentially fit the data...
- fritzo 3y agoRight, show a posterior distribution not some hallucinated point estimate.
- V1ndaar 3y agoCheck out the paper and not a PR piece [0]. [0]: https://stsci-opo.org/STScI-01HA2G716KS9YGAGVY1WBVFJ8Y.pdf https://stsci-opo.org/STScI-01HA2G716KS9YGAGVY1WBVFJ8Y.pdf
- gus_massa 3y ago[I'm not an expert is spectroscopy, but let me guess.] The bump at 4.3um looks real, and it seams to be an standard absorción of CO2. https://www.quora.com/Does-CO2-absorb-all-infrared-frequencies-near-infrared-far-infrared-etc-or-does-it-just-absorb-one-frequency https://www.quora.com/Does-CO2-absorb-all-infrared-frequenci... The bump at 1.2, 1.4 and 2.4um looks real. I found this showing a peak for CH4 at 2.325um. http://www.astrochem.org/data/CH4H2O.php http://www.astrochem.org/data/CH4H2O.php [Sorry for the sources, but I'm not an expert is spectroscopy.] My guess is that they assumed something like a% * CH4 + b% * CO2 + c% * H2O + others and get the best fit for a%, b%, c%, ... using the white points. Later, using these numbers they draw the blue line. The peak for DMS is not clear for my untrained eye, so I can't guess what they did there. (Perhaps it's just the best fit.) It would be nice to see the a graph of the blue line they guessed with DMS and a superimposed red line with and atmosphere with an alternative atmosphere where the DMS is replaced with something uninteresting (N2? H2O? More CH4? I have no idea what is uninteresting here.)
- bigbillheck 3y ago> How can they infer the blue fit from the (noisy) white points? By having a detailed model, and modern probabilistic techniques: The planet’s terminator is modelled as a plane-parallel atmosphere in hydrostatic equilibrium, with uniform chemical composition. The chemical abundances and pressure-temperature (P-T) profile are free parameters in the model. The retrieval framework follows a free chemistry approach, whereby the individual mixing ratio of each chemical species is a free parameter.... Our canonical model comprises of 22 free parameters overall: 11 corresponding to the individual mixing ra- tios of the above chemical species, 6 for the P-T profile, 4 for the clouds/hazes and 1 for the reference pressure Pref , defined as the pressure at a fixed planetary radius of 2.61 R⊕. The Bayesian inference and parameter estimation is conducted using the MultiNest nested sam- pling algorithm (Feroz et al. 2009) implemented through PyMultiNest. (Sections 2.4 and 3.1 from https://stsci-opo.org/STScI-01HA2G716KS9YGAGVY1WBVFJ8Y.pdf https://stsci-opo.org/STScI-01HA2G716KS9YGAGVY1WBVFJ8Y.pdf) > And even if there is a detection, it looks like many other models could potentially fit the data... Name three.
- deleted 3y ago[deleted]
- fritzo 3y agoPaywalled paper: https://www.nature.com/articles/s41550-019-0878-9 https://www.nature.com/articles/s41550-019-0878-9 Preprint: https://arxiv.org/abs/1909.05218 https://arxiv.org/abs/1909.05218 Figure 2 pp. 14 of the preprint shows much more plausible error bounds on the curve fit. That press release "best fit" curve is merely an artist's conception.
- V1ndaar 3y agoNope, that is the old paper about Hubble measurements of the same planet. The preprint of the Webb based paper is here [0] from here [1]. [0]: https://stsci-opo.org/STScI-01HA2G716KS9YGAGVY1WBVFJ8Y.pdf https://stsci-opo.org/STScI-01HA2G716KS9YGAGVY1WBVFJ8Y.pdf [1]: https://webbtelescope.org/contents/news-releases/2023/news-2023-139 https://webbtelescope.org/contents/news-releases/2023/news-2...
- divbzero 3y ago> "Our ultimate goal is the identification of life on a habitable exoplanet, which would transform our understanding of our place in the universe," concluded Madhusudhan. What sort of observation or measurement would allow us to identify life on an exoplanet?
- gus_massa 3y agoA lot of O2. As far as we know, the only source of a lot of O2 in the atmosphere are photosynthetic bacteria-like. So it will be a clear sign of life. There are some more subtle cases, like the one discussed in this paper.
- perihelions 3y agoWhat an unintuitive and sketchy-looking Bayesian model. They only have 11 chemicals in the database they're matching that messy IR spectrum against: 6 reasonable ones, and 5 bullshit ones that are only there because theory papers suggested that they'd be biomarkers of alien life. And, fit to just those 11 chemicals, the best-fit includes one of the bullshit ones (dimethyl sulfide, (CH₃)₂S). https://stsci-opo.org/STScI-01HA2G716KS9YGAGVY1WBVFJ8Y.pdf https://stsci-opo.org/STScI-01HA2G716KS9YGAGVY1WBVFJ8Y.pdf Is this approach, like, sane? I'm not a Bayesian statistics expert.
- kjkjadksj 3y agoA true Bayesian I don’t think would use evidence for life on earth as the silver bullet for life elsewhere. They’d at least set up a model that considers all possible planets in the entire universe and test to see if these putative signatures even give you the power to identify earth as a life holding planet with confidence.
- biggestlou 3y agoI’m still looking for intelligent life on this planet
- rbanffy 3y agoUgh. If my napkin math is right, it's about 2G's for the same density as Earth. Very unpleasant planet.
- billforsternz 3y agoI picked up a random book in the science section of the city library today and opening it to a random page I started reading about an exciting "goldilocks" exoplanet discovery from 2015. Apparently this was the first exo-planet which had a positive spectroscopic identification of water in the atmosphere. It was a rocky world, 2 billion years old, 8 times Earth's size (mass?), on a 33 day orbit around a red dwarf. K-something-or-other. The book said the really exciting discoveries will happen when Webb comes online in 2021. The link is down, but someone mentions this planet is 8 x Earth size down thread. I wonder if it's the same planet?
- truculent 3y agoI think this is supposedly a Hycean (ocean + hydrogen atmosphere) planet, rather than rocky. Unless those categories aren’t exclusive.
- billforsternz 3y agoSorry, didn't notice this in a timely way. I went back to the library to check, and indeed the planet I was reading about was K2-18b. The book at least says that K2-18b is a Super-Earth and will almost certainly have a molten rocky core.
- stevenwoo 3y agoMaybe you mixed up the dates slightly? K2-18b (name of the exo-planet) orbiting star K2-18 was discovered in 2015 but the water was not detected until 2019.
- billforsternz 3y agoSorry, didn't notice the reply in a timely way. I went back to the library, the book was "The Universe" by Andrew Cohen. It was indeed K2-18B, discovered by Kepler in 2015. It says that the water was discovered by Hubble later, so presumably 2019.