A team of astronomers have detected what they call the most promising signs to date of a possible biosignature, or signs of past or present life linked to biological activity, on an exoplanet named K2-18b. But the study authors, and other experts, remain cautious and have not declared a definitive discovery of life beyond our planet.Related video above: Star swallows planet in one big gulpUsing the James Webb Space Telescope, the team detected chemical fingerprints within the atmosphere of K2-18b that suggest the presence of dimethyl sulfide or DMS, and potentially dimethyl disulfide or DMDS. On Earth, both molecules are only produced by microbial life, typically marine phytoplankton.A study detailing the findings was published Thursday in The Astrophysical Journal Letters.K2-18b, located 124 light-years from Earth, could be a Hycean world: a potentially habitable planet entirely covered in liquid water with a hydrogen-rich atmosphere, said lead study author Nikku Madhusudhan, professor of astrophysics and exoplanetary science at the University of Cambridge바카라 게임 웹사이트�s Institute of Astronomy.Madhusudhan and his colleagues first theorized the concept of Hycean worlds in 2021 after determining that there may be liquid water oceans on K2-18b.The planet is located within the habitable zone of its star, meaning that the world is at just the right temperature and distance from the star to host liquid water on its surface.바카라 게임 웹사이트�Earlier theoretical work had predicted that high levels of sulfur-based gases like DMS and DMDS are possible on Hycean worlds,바카라 게임 웹사이트� Madhusudhan said in a statement. 바카라 게임 웹사이트�And now we바카라 게임 웹사이트�ve observed it, in line with what was predicted. Given everything we know about this planet, a Hycean world with an ocean that is teeming with life is the scenario that best fits the data we have.바카라 게임 웹사이트�Webb telescope detectionsIt바카라 게임 웹사이트�s possible that the molecules were produced by another unknown chemical process on the planet, which does not require life.The latest findings build on previous research by the same group of astronomers, who also detected carbon dioxide and methane within the planet바카라 게임 웹사이트�s atmosphere using Webb바카라 게임 웹사이트�s Near-Infrared Imager and Slitless Spectrograph and Near-Infrared Spectrograph instruments. The team made the new detection using Webb바카라 게임 웹사이트�s Mid-Infrared Instrument.바카라 게임 웹사이트�This is an independent line of evidence, using a different instrument than we did before and a different wavelength range of light, where there is no overlap with the previous observations,바카라 게임 웹사이트� Madhusudhan said. 바카라 게임 웹사이트�The signal came through strong and clear.바카라 게임 웹사이트�But Madhusudhan and his coauthors acknowledge that more data is needed before claiming direct evidence of life on another world. The team believes that between 16 and 24 hours of follow-up observations using Webb will make that possible.바카라 게임 웹사이트�It바카라 게임 웹사이트�s important that we바카라 게임 웹사이트�re deeply (skeptical) of our own results, because it바카라 게임 웹사이트�s only by testing and testing again that we will be able to reach the point where we바카라 게임 웹사이트�re confident in them,바카라 게임 웹사이트� Madhusudhan said. 바카라 게임 웹사이트�That바카라 게임 웹사이트�s how science has to work.바카라 게임 웹사이트�However, other experts believe that while the results promise excitement, confirming the existence of life beyond Earth 바카라 게임 웹사이트� and even deciding what type of exoplanet K2-18b is 바카라 게임 웹사이트� will take much more time and data.Astrophysicist Sara Seager, a professor of physics, planetary science, aeronautics and astronautics at the Massachusetts Institute of Technology, said independent teams have completely different interpretations of the planet itself. Seager was not involved in the new research.바카라 게임 웹사이트�Some propose a Hycean world, others suggest a hot magma ocean 바카라 게임 웹사이트� a planet with molten rock beneath a hydrogen-rich atmosphere, which is about as inhospitable as it gets 바카라 게임 웹사이트� and still others see it as a mini-Neptune,바카라 게임 웹사이트� Seager said, referring to worlds that are larger than Earth but smaller than Neptune. For reference, K2-18b is 8.6 times as massive and 2.6 times as large as Earth.Seager believes this finding, which suggests a candidate for a biosignature, 바카라 게임 웹사이트�will remain in the candidate category indefinitely.바카라 게임 웹사이트�바카라 게임 웹사이트�For nearly 100 years, astronomers have wrestled with the idea that certain gases in a planet바카라 게임 웹사이트�s atmosphere 바카라 게임 웹사이트�don바카라 게임 웹사이트�t belong바카라 게임 웹사이트� 바카라 게임 웹사이트� that they바카라 게임 웹사이트�re so reactive they shouldn바카라 게임 웹사이트�t exist without being continually replenished, possibly by life,바카라 게임 웹사이트� Seager said via email. 바카라 게임 웹사이트�This idea traces back to James Jeans in 1930, who first identified molecular oxygen in Earth바카라 게임 웹사이트�s atmosphere as a sign of life, and used similar logic to place limits on oxygen in Venus바카라 게임 웹사이트� atmosphere. Now, with thousands of exoplanets in view, the temptation to overinterpret is strong 바카라 게임 웹사이트� and some are jumping the gun. When it comes to K2-18 b, enthusiasm is outpacing evidence.바카라 게임 웹사이트�An 바카라 게임 웹사이트�exciting바카라 게임 웹사이트� hintWhen Madhusudhan and his team previously observed K2-18b, they detected a weak signal that might fit the hypothesis that the planet is a Hycean world.바카라 게임 웹사이트�We didn바카라 게임 웹사이트�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,바카라 게임 웹사이트� he said.Webb has the observational capability to peer through the atmosphere of exoplanets, or planets beyond our solar system. As exoplanets pass in front of their host star, from the perspective of Earth, light moves through their atmospheres, allowing Webb to detect the chemical signatures of gases within them.Both dimethyl sulfide and dimethyl disulfide, which are part of the same chemical group, have overlapping characteristics, which is why the results can바카라 게임 웹사이트�t definitively differentiate between the two molecules, but future observations might, the study authors said.On Earth, concentrations of dimethyl sulfide and dimethyl disulfide are typically below one part per billion in volume. However, the team estimates the presence of these molecules to be thousands of times stronger on K2-18b.바카라 게임 웹사이트�The inference of these biosignature molecules poses profound questions concerning the processes that might be producing them,바카라 게임 웹사이트� said study coauthor Subhajit Sarkar, a lecturer in the astronomy group at Cardiff University in Wales, in a statement.Eddie Schwieterman, assistant professor of astrobiology at the University of California, Riverside, is 바카라 게임 웹사이트�somewhat skeptical but very intrigued and excited about what바카라 게임 웹사이트�s next.바카라 게임 웹사이트� Schwieterman, who has studied K2-18b in the past, was not involved in the new research.His group바카라 게임 웹사이트�s research found that in order to sustain the abundance of dimethyl sulfide in K2-18b바카라 게임 웹사이트�s atmosphere, 바카라 게임 웹사이트�a production rate of about 20 times that of Earth바카라 게임 웹사이트�s DMS production is required.바카라 게임 웹사이트�바카라 게임 웹사이트�This is a high bar, but plausible considering local areas in Earth바카라 게임 웹사이트�s oceans are far more productive than the global average,바카라 게임 웹사이트� he said. 바카라 게임 웹사이트�This threshold also poses an obstacle to attributing potential DMS to abiotic (non-biological) sources, since those abiotic sources would have to be much larger than any known ones.바카라 게임 웹사이트�But Schwieterman said that first, scientists need to confirm that dimethyl sulfide is really present in the atmosphere of K2-18b, which will require validation from multiple independent groups who study the same data and analyze it for the chemical signature of the molecules. Madhusudhan said the data the study team analyzed will be released next week, so other astronomers can do just that.Next, Schwieterman wants to see additional Webb observations with a higher level of statistical significance to see whether the interpretation of dimethyl sulfide being present holds. Searching for the signatures of these molecules in atmospheres of other similarly sized planets within the habitable zones of their stars would also help, although it바카라 게임 웹사이트�s a process that will take years.바카라 게임 웹사이트�I do have at (least) one reason to be skeptical, which is that I바카라 게임 웹사이트�d anticipate the presence of ethane (C2H6) to accompany DMS/DMDS if those gases were present,바카라 게임 웹사이트� he said. 바카라 게임 웹사이트�This is because UV rays from the star would break apart the DMS/DMDS into components we바카라 게임 웹사이트�d predict would react to form ethane. The absence of ethane makes me think we바카라 게임 웹사이트�ve missed something. Perhaps our models are wrong, or perhaps the DMS/DMDS isn바카라 게임 웹사이트�t there.바카라 게임 웹사이트�Schwieterman believes there is a lot of work to be done to validate the finding and assess the biosignature hypothesis presented by the paper.A threshold for lifeThe research team that authored the new paper says the observations have reached the three-sigma level of significance, or a 0.3% probability that the detections occurred by chance. For a scientific discovery, the observations must meet a five-sigma threshold, or below a 0.00006% that the observations occurred by chance.While the findings don바카라 게임 웹사이트�t represent a clear detection of dimethyl sulfide and dimethyl disulfide, 바카라 게임 웹사이트�it is a step in the right direction,바카라 게임 웹사이트� said Dr. David Clements, an astrophysicist at Imperial College London. Clements was not involved in the research.Madhusudhan believes his team바카라 게임 웹사이트�s finding is a 바카라 게임 웹사이트�major landmark in our search for life바카라 게임 웹사이트� that ushers in a new era.바카라 게임 웹사이트�In my mind, it is no longer a question of whether we will find life if such life exists,바카라 게임 웹사이트� he said. 바카라 게임 웹사이트�We have demonstrated that we have the capability to do so with our initial current findings at reasonable significance. A bigger question in my mind is whether we as a species are prepared to find life as we don바카라 게임 웹사이트�t know it. We as a society, as a species, should come together and ask ourselves the question: What is it that constitutes life elsewhere?바카라 게임 웹사이트�