Largest celestial object of its kind discovered in the distant universe

‘Flooding could end southern Appalachia': the scientists on an urgent mission to save lives

Yahoo

3 hours ago

Yahoo

‘Flooding could end southern Appalachia': the scientists on an urgent mission to save lives

The abandoned homes and razed lots along the meandering Troublesome Creek in rural eastern Kentucky is a constant reminder of the 2022 catastrophic floods that killed dozens of people and displaced thousands more. Among the hardest hit was Fisty, a tiny community where eight homes, two shops and nine people including a woman who uses a wheelchair, her husband and two children, were swept away by the rising creek. Some residents dismissed cellphone alerts of potential flooding due to mistrust and warning fatigue, while for others it was already too late to escape. Landslides trapped the survivors and the deceased for several days. In response, geologists from the University of Kentucky secured a grant from the National Science Foundation (NSF) and raced around collecting perishable data in hope of better understanding the worst flooding event to hit the region in a generation. On a recent morning in Fisty, Harold Baker sat smoking tobacco outside a new prefabricated home while his brother James worked on a car in a makeshift workshop. With no place else to go, the Baker family rebuilt the workshop on the same spot on Troublesome Creek with financial assistance from the Federal Emergency Management Agency (Fema). 'I feel depressed. Everyone else is gone now. The days are long. It feels very lonely when the storms come in,' said Baker, 55, whose four dogs drowned in 2022. With so few people left, the car repair business is way down, the road eerily quiet. Since the flood that took everything, Harold and James patrol the river every time it rains. The vigilance helped avert another catastrophe on Valentine's Day after another so-called generational storm. No one died, but the trauma, like the river, came roaring back. Related: How bad will flooding get by 2100? These AI images show US destinations underwater 'I thought we were going to lose everything again. It was scary,' said Baker. At this spot in July 2022, geologist Ryan Thigpen found flood debris on top of two-storey buildings – 118in (3 metres) off the ground. The water mark on Harold's new trailer shows the February flood hit 23in. Troublesome Creek is a 40-mile narrow tributary of the north fork of the Kentucky River, which, like many waterways across southern Appalachia, does not have a single gauge. Yet these rural mountain hollows are getting slammed over and over by catastrophic flooding – and landslides – as the climate crisis increases rainfall across the region and warmer waters in the Gulf of Mexico turbocharge storms. Two years after 45 people died in the 2022 floods, the scale of disaster grew with Hurricane Helene, which killed more than 230 people with almost half the deaths in Appalachia, after days of relentless rain turned calm streams into unstoppable torrents. Another 23 people died during the February 2025 rains, then 24 more in April during a four-day storm that climate scientists found was made significantly more likely and more severe by the warming planet. The extreme weather is making life unbearable and economically unviable for a chronically underserved region where coal was once king, and climate skepticism remains high. Yet little is known about flooding in the Appalachian region. It's why the geologists – also called earth scientists – got involved. 'This is where most people are going to die unless we create reliable warning systems and model future flood risks for mitigation and to help mountain communities plan for long-term resilience. Otherwise, these extreme flooding events could be the end of southern Appalachia,' said Thigpen. Amid accelerating climate breakdown, the urgency of the mission is clear. Yet this type of applied science could be derailed – or at least curtailed – by the unprecedented assault on science, scientists and federal agencies by Donald Trump and his billionaire donors. Danielle Baker, James's wife, had her bags packed a week in advance of the February flood and was glued to local television weather reports, which, like the geologists, rely on meteorological forecasting by the taxpayer-funded National Weather Service (NWS). She was 'scared to death' watching the creek rise so high again. But this time, the entire family, including 11 dogs and several cats, evacuated to the church on the hill, where they waited 26 hours for the water to subside. 'The people in this community are the best you could meet, but it's a ghost town now. I didn't want to rebuild so close to the creek, but we had nowhere else to go. Every time it rains, I can't sleep,' she said, wiping away tears with her shirt. Danielle was unaware of Trump's plans to dismantle Fema and slash funding from the NWS and NSF. 'A lot of people here would not know what to do without Fema's help. We need more information about the weather, better warnings, because the rains are getting worse,' she said. A day after the Guardian's visit in mid-May, an NWS office in eastern Kentucky scrambled to cover the overnight forecast as severe storms moved through the region, triggering multiple tornadoes that eventually killed 28 people. Hundreds of staff have left the NWS in recent months, through a combination of layoffs and buyouts at the behest of Trump mega-donor Elon Musk's so-called 'department of government efficiency' (Doge). It doesn't matter if people don't believe in climate change. It's going to wallop them anyway … This is a new world of extremes and cascading hazards Ryan Thigpen, geologist Yet statewide, two-thirds of Kentuckians voted for Trump last year, with his vote share closer to 80% in rural communities hit hard by extreme weather, where many still blame Barack Obama for coal mine closures. 'It doesn't matter if people don't believe in climate change. It's going to wallop them anyway. We need to think about watersheds differently. This is a new world of extremes and cascading hazards,' said Thigpen, the geologist. *** The rapidly changing climate is rendering the concept of once-in-a-generation floods, which is mostly based on research by hydrologists going back a hundred years or so, increasingly obsolete. Geologists, on the other hand, look back 10,000 years, which could help better understand flooding patterns when the planet was warmer. Thigpen is spearheading this close-knit group of earth scientists from the university's hazards team based in Lexington. On a recent field trip, nerdy jokes and constant teasing helped keep the mood light, but the scientists are clearly affected by the devastation they have witnessed since 2022. The team has so far documented more than 3,000 landslides triggered by that single extreme rain event, and are still counting. This work is part of a broader statewide push to increase climate resiliency and bolster economic growth using Kentucky-specific scientific research. Last year, the initiative got a major boost when the state secured $24m from the NSF for a five-year research project involving eight Kentucky institutions that has created dozens of science jobs and hundreds of new student opportunities. The grant helped pay for high-tech equipment – drones, radars, sensors and computers – the team needs to collect data and build models to improve hazard prediction and create real-time warning systems. After major storms, the team measures water levels and analyzes the sediment deposits left behind to calculate the scale and velocity of the flooding, which in turn helps calibrate the model. The models help better understand the impact of the topography and each community's built and natural environment – important for future mitigation. In these parts, coal was extracted using mountaintop mine removal, which drastically altered the landscape. Mining – and redirected waterways – can affect the height of a flood, according to a recent study by PhD student Meredith Swallom. A paleo-flood project is also under way, and another PhD student, Luciano Cardone, will soon begin digging into a section of the Kentucky riverbank to collect layers of sediment that holds physical clues on the date, size and velocity of ancient floods. Cardone, who found one local missionary's journal describing flooding in 1795, will provide a historical or geological perspective on catastrophic flooding in the region, which the team believe will help better predict future hazards under changing climatic conditions. All this data is analyzed at the new lab located in the Kentucky Geological Survey (KGS) department, where super-powerful computers are positioned around a ceiling-to-floor black board, with a groovy lamp and artwork to get the creative mathematical juices flowing. So far the team has developed one working flood risk model for a single section of the Kentucky River. This will serve as a template, as each watershed requires its own model so that the data is manageable, precise and useful. This sort of applied science has the capacity to directly improve the lives of local people, including many Trump voters, as well as benefiting other mountainous flood-prone areas across the US and globally. But a flood warning system can only work if there is reliable meteorological forecasting going forward. The floods have made this a ghost town. I doubt it will survive another one. If you mess with Mother Nature, you lose Thomas Hutton of Kentucky Reports suggest NWS weather balloons, which assess storm risk by measuring wind speed, humidity, temperature and other conditions that satellites may not detect, have been canceled in recent weeks from Nebraska to Florida due to staff shortages. At the busiest time for storm predictions, deadly heatwaves and wildfires, weather service staffing is down by more than 10% and, for the first time in almost half a century, some forecasting offices no longer have 24/7 cover. Trump's team is also threatening to slash $1.52bn from the National Oceanic and Atmospheric Administration (Noaa), the weather service's parent agency, which also monitors climate trends, manages coastal ecosystems and supports international shipping, among other things. 'To build an effective and trusted warning system, we need hyper-local data, including accurate weather forecasts and a more robust network of gauges,' said Summer Brown, a senior lecturer at the University of Kentucky's earth and environmental sciences department. 'The thought of weakening our basic weather data is mind-boggling.' It's impossible not to worry about the cuts, especially as the grand plan is to create a southern Appalachian flood and hazard centre to better understand and prepare the entire region's mountain communities for extreme weather and related hazards, including flash floods, landslides and tornadoes. For this, the team is currently awaiting a multimillion-dollar grant decision from the NSF, in what until recently was a merit-based, peer-reviewed process at the federal agency. The NSF director resigned in April after orders from the White House to accept a 55% cut to the $9bn budget and fire half of the 1,700-person staff. Then, in an unprecedented move, a member of the governing body stepped down, lambasting Musk's unqualified Doge team for interfering in grant decisions. The days are long. It feels very lonely when the storms come in Harold Baker of Kentucky The NSF is the principal federal investor in basic science and engineering, and the proposed cut will be devastating in the US and globally. 'Rivers are different all over Appalachia, and if our research continues, we can build accurate flood and landslide models that help communities plan for storms in a changing climate,' said Jason Dortch, who set up the flood lab. 'We've submitted lots of great grant proposals, and while that is out of our hands, we will continue to push forwarded however we can.' *** Fleming-Neon is a former mining community in Letcher county with roughly 500 residents – a decline of almost 40% in the past two decades. The town was gutted by the 2022 storm, and only two businesses, a car repair shop and a florist, reopened. The launderette, pharmacy, dentist, clothing store and thrift shop were all abandoned. Randall and Bonnie Kincer, a local couple who have been married for 53 years, run the flower shop from an old movie theater on Main Street, which doubles up as a dance studio for elementary school children. The place was rammed with 120in of muddy water in 2022. In February, it was 52in, and everything still reeks of mould. The couple have been convinced by disinformation spread by conspiracy theorists that the recent catastrophic floods across the region, as well as Helene, were caused by inadequate river dredging and cloud seeding. The town's sorry plight, according to the Kincers, is down to deliberate manipulation of the weather system paid for by mining companies to flood out the community in order to gain access to lithium. (There are no significant lithium deposits in the area.) Bonnie, 74, is on the brink of giving up on the dance classes that she has taught since sophomore year, but not on Trump. 'I have total confidence in President Trump. The [federal] cuts will be tough for a little while but there's a lot of waste, so it will level out,' said Bonnie, who is angry about not qualifying for Fema assistance. 'We used all our life savings fixing the studio. But I cannot shovel any more mud, not even for the kids. I am done. I have PTSD. We are scared to death,' she said, breaking down in tears several times. The fear is understandable. On the slope facing the studio, a tiered retainer wall has been anchored into the hill to stabilize the earth and prevent an avalanche from destroying the town below. And at the edge of town, next to the power station on an old mine site, is a towering pile of black sludgy earth littered with lumps of shiny coal – the remnants of a massive landslide that happened as residents cleaned up after the February storm. Thomas Hutton's house was swamped with muddy water after the landslide blocked the creek, forcing it to temporarily change course towards a residential street. 'The floods have made this a ghost town. I doubt it will survive another one. If you mess with Mother Nature, you lose,' said Hutton, 74, a retired miner. The geologists fly drones fitted with Lidar (light detection and ranging): a remote sensing technology that uses pulsed lasers to create high-resolution, 3D, color models of the Earth's surface, and can shoot through trees and human-made structures to detect and monitor changes in terrain including landslides. The affordability and precision of the China-made Lidar has been a 'game changer' for landslides, but prices have recently rocketed thanks to Trump's tariff war. Related: Trump cuts will lead to more deaths in disasters, expert warns: 'It is really scary' The Lidar picked up fairly recent deforestation above the Fleming-Neon power plant, which likely further destabilized the earth. The team agrees that the landslide could keep moving, but without good soil data it's impossible to know when. Last year's NSF grant funded new soil and moisture sensors, as well as mini weather stations, which the landslide team is in the process of installing on 14 steep slopes in eastern Kentucky – the first time this has been done – including one opposite Hutton's house. Back at the lab, the geologists will use the data the sensors send back every 15 minutes to create models – and eventually a website where residents and local emergency managers can see how the soil moisture is changing in real time. The goal is to warn communities when there is a high landslide risk based on the soil saturation – and rain forecast. 'We have taken so many resources from these slopes. We need to understand them better,' said Sarah Johnson, a landslide expert. 'We're not sitting in an ivory tower making money from research. The work we do is about making communities safer.'

A surprising study revealed biological activity on a distant planet. Weeks later, scientists say there's more to the story

Yahoo

8 hours ago

Yahoo

A surprising study revealed biological activity on a distant planet. Weeks later, scientists say there's more to the story

Sign up for CNN's Wonder Theory science newsletter. Explore the universe with news on fascinating discoveries, scientific advancements and more. A tiny sign revealed in April seemed like it might change the universe as we know it. Astronomers had detected just a hint, a glimmer of two molecules swirling in the atmosphere of a distant planet called K2-18b — molecules that on Earth are produced only by living things. It was a tantalizing prospect: the most promising evidence yet of an extraterrestrial biosignature, or traces of life linked to biological activity. But only weeks later, new findings suggest the search must continue. 'It was exciting, but it immediately raised several red flags because that claim of a potential biosignature would be historic, but also the significance or the strength of the statistical evidence seemed to be too high for the data,' said Dr. Luis Welbanks, a postdoctoral research scholar at Arizona State University's School of Earth and Space Exploration. While the molecules identified on K2-18b by the April study — dimethyl sulfide, or DMS, and dimethyl disulfide, or DMDS — are associated largely with microbial organisms on our planet, scientists point out that the compounds can also form without the presence of life. Now, three teams of astronomers not involved with the research, including Welbanks, have assessed the models and data used in the original biosignature discovery and got very different results, which they have submitted for peer review. Meanwhile, the lead author of the April study, Nikku Madhusudhan, and his colleagues have conducted additional research that they say reinforces their previous finding about the planet. And it's likely that additional observations and research from multiple groups of scientists are on the horizon. The succession of research papers revolving around K2-18b offers a glimpse of the scientific process unfolding in real time. It's a window into the complexities and nuances of how researchers search for evidence of life beyond Earth — and shows why the burden of proof is so high and difficult to reach. Located 124 light-years from Earth, K2-18b is generally considered a worthy target to scour for signs of life. It is thought to be a Hycean world, a planet entirely covered in liquid water with a hydrogen-rich atmosphere, according to previous research led by Madhusudhan, a professor of astrophysics and exoplanetary science at the University of Cambridge's Institute of Astronomy. And as such, K2-18b has rapidly attracted attention as a potentially habitable place beyond our solar system. Convinced of K2-18b's promise, Madhusudhan and his Cambridge colleagues used observations of the planet by the largest space telescope in operation, the James Webb Space Telescope, to study the planet further. But two scientists at the University of Chicago — Dr. Rafael Luque, a postdoctoral scholar in the university's department of astronomy and astrophysics, and Michael Zhang, a 51 Pegasi b / Burbidge postdoctoral fellow — spotted some problems with what they found. After reviewing Madhusudhan and his team's April paper, which followed up on their 2023 research, Luque and Zhang noticed that the Webb data looked 'noisy,' Luque said. Noise, caused by imperfections in the telescope and the rate at which different particles of light reach the telescope, is just one challenge astronomers face when they study distant exoplanets. Noise can distort observations and introduce uncertainties into the data, Zhang said. Trying to detect specific gases in distant exoplanet atmospheres introduces even more uncertainty. The most noticeable features from a gas like dimethyl sulfide stem from a bond of hydrogen and carbon molecules — a connection that can stretch and bend and absorb light at different wavelengths, making it hard to definitively detect one kind of molecule, Zhang said. 'The problem is basically every organic molecule has a carbon-hydrogen bond,' Zhang said. 'There's hundreds of millions of those molecules, and so these features are not unique. If you have perfect data, you can probably distinguish between different molecules. But if you don't have perfect data, a lot of molecules, especially organic molecules, look very similar, especially in the near-infrared.' Delving further into the paper, Luque and Zhang also noticed that the perceived temperature of the planet appeared to increase sharply from a range of about 250 Kelvin to 300 Kelvin (-9.67 F to 80.33 F or -23.15 C to 26.85 C) in research Madhusudhan published in 2023 to 422 Kelvin (299.93 F or 148.85 C) in the April study. Such harsh temperatures could change the way astronomers think about the planet's potential habitability, Zhang said, especially because cooler temperatures persist in the top of the atmosphere — the area that Webb can detect — and the surface or ocean below would likely have even higher temperatures. 'This is just an inference only from the atmosphere, but it would certainly affect how we think about the planet in general,' Luque said. Part of the issue, he said, is that the April analysis didn't include data collected from all three Webb instruments Madhusudhan's team used over the past few years. So Luque, Zhang and their colleagues conducted a study combining all the available data to see whether they could achieve the same results, or even find a higher amount of dimethyl sulfide. They found 'insufficient evidence' of both molecules in the planet's atmosphere. Instead, Luque and Zhang's team spotted other molecules, like ethane, that could fit the same profile. But ethane does not signify life. Arizona State's Welbanks and his colleagues, including Dr. Matt Nixon, a postdoctoral researcher in the department of astronomy at the University of Maryland College Park, also found what they consider a fundamental problem with the April paper on K2-18b. The concern, Welbanks said, was with how Madhusudhan and his team created models to show which molecules might be in the planet's atmosphere. 'Each (molecule) is tested one at a time against the same minimal baseline, meaning every single model has an artificial advantage: It is the only explanation permitted,' Welbanks said. When Welbanks and his team conducted their own analysis, they expanded the model from Madhusudhan's study. '(Madhusudhan and his colleagues) didn't allow for any other chemical species that could potentially be producing these small signals or observations,' Nixon said. 'So the main thing we wanted to do was assess whether other chemical species could provide an adequate fit to the data.' When the model was expanded, the evidence for dimethyl sulfide or dimethyl disulfide 'just disappears,' Welbanks said. Madhusudhan believes the studies that have come out after his April paper are 'very encouraging' and 'enabling a healthy discussion on the interpretation of our data on K2-18b.' He reviewed Luque and Zhang's work and agreed that their findings don't show a 'strong detection for DMS or DMDS.' When Madhusudhan's team published the paper in April, he said the observations reached the three-sigma level of significance, or a 0.3% probability that the detections occurred by chance. For a scientific discovery that is highly unlikely to have occurred by chance, the observations must meet a five-sigma threshold, or below a 0.00006% probability that the observations occurred by chance. Meeting such a threshold will require many steps, Welbanks said, including repeated detections of the same molecule using multiple telescopes and ruling out potential nonbiological sources. While such evidence could be found in our lifetime, it is less likely to be a eureka moment and more a slow build requiring a consensus among astronomers, physicists, biologists and chemists. 'We have never reached that level of evidence in any of our studies,' Madhusudhan wrote in an email. 'We have only found evidence at or below 3-sigma in our two previous studies (Madhusudhan et al. 2023 and 2025). We refer to this as moderate evidence or hints but not a strong detection. I agree with (Luque and Zhang's) claim which is consistent with our study and we have discussed the need for stronger evidence extensively in our study and communications.' In response to the research conducted by Welbanks' team, Madhusudhan and his Cambridge colleagues have authored another manuscript expanding the search on K2-18b to include 650 types of molecules. They have submitted the new analysis for peer review. 'This is the largest search for chemical signatures in an exoplanet to date, using all the available data for K2-18b and searching through 650 molecules,' Madhusudhan said. 'We find that DMS continues to be a promising candidate molecule in this planet, though more observations are required for a firm detection as we have noted in our previous studies.' Welbanks and Nixon were pleased that Madhusudhan and his colleagues addressed the concerns raised but feel that the new paper effectively walks back central claims made in the original April study, Welbanks said. 'The new paper tacitly concedes that the DMS/DMDS detection was not robust, yet still relies on the same flawed statistical framework and a selective reading of its own results,' Welbanks said in an email. 'While the tone is more cautious (sometimes), the methodology continues to obscure the true level of uncertainty. The statistical significance claimed in earlier work was the product of arbitrary modeling decisions that are not acknowledged.' Luque said the Cambridge team's new paper is a step in the right direction because it explores other possible chemical biosignatures. 'But I think it fell short in the scope,' Luque said. 'I think it restricted itself too much into being a rebuttal to the (Welbanks) paper.' Separately, however, the astronomers studying K2-18b agree that pushing forward on researching the exoplanet contributes to the scientific process. 'I think it's just a good, healthy scientific discourse to talk about what is going on with this planet,' Welbanks said. 'Regardless of what any single author group says right now, we don't have a silver bullet. But that is exactly why this is exciting, because we know that we're the closest we have ever been (to finding a biosignature), and I think we may get it within our lifetime, but right now, we're not there. That is not a failure. We're testing bold ideas.'

How one planet is revealing why it's so hard to detect life beyond Earth

Yahoo

14 hours ago

Yahoo

How one planet is revealing why it's so hard to detect life beyond Earth

Sign up for CNN's Wonder Theory science newsletter. Explore the universe with news on fascinating discoveries, scientific advancements and more. A tiny sign revealed in April seemed like it might change the universe as we know it. Astronomers had detected just a hint, a glimmer of two molecules swirling in the atmosphere of a distant planet called K2-18b — molecules that on Earth are produced only by living things. It was a tantalizing prospect: the most promising evidence yet of an extraterrestrial biosignature, or traces of life linked to biological activity. But only weeks later, new findings suggest the search must continue. 'It was exciting, but it immediately raised several red flags because that claim of a potential biosignature would be historic, but also the significance or the strength of the statistical evidence seemed to be too high for the data,' said Dr. Luis Welbanks, a postdoctoral research scholar at Arizona State University's School of Earth and Space Exploration. While the molecules identified on K2-18b by the April study — dimethyl sulfide, or DMS, and dimethyl disulfide, or DMDS — are associated largely with microbial organisms on our planet, scientists point out that the compounds can also form without the presence of life. Now, three teams of astronomers not involved with the research, including Welbanks, have assessed the models and data used in the original biosignature discovery and got very different results, which they have submitted for peer review. Meanwhile, the lead author of the April study, Nikku Madhusudhan, and his colleagues have conducted additional research that they say reinforces their previous finding about the planet. And it's likely that additional observations and research from multiple groups of scientists are on the horizon. The succession of research papers revolving around K2-18b offers a glimpse of the scientific process unfolding in real time. It's a window into the complexities and nuances of how researchers search for evidence of life beyond Earth — and shows why the burden of proof is so high and difficult to reach. Located 124 light-years from Earth, K2-18b is generally considered a worthy target to scour for signs of life. It is thought to be a Hycean world, a planet entirely covered in liquid water with a hydrogen-rich atmosphere, according to previous research led by Madhusudhan, a professor of astrophysics and exoplanetary science at the University of Cambridge's Institute of Astronomy. And as such, K2-18b has rapidly attracted attention as a potentially habitable place beyond our solar system. Convinced of K2-18b's promise, Madhusudhan and his Cambridge colleagues used observations of the planet by the largest space telescope in operation, the James Webb Space Telescope, to study the planet further. But two scientists at the University of Chicago — Dr. Rafael Luque, a postdoctoral scholar in the university's department of astronomy and astrophysics, and Michael Zhang, a 51 Pegasi b / Burbidge postdoctoral fellow — spotted some problems with what they found. After reviewing Madhusudhan and his team's April paper, which followed up on their 2023 research, Luque and Zhang noticed that the Webb data looked 'noisy,' Luque said. Noise, caused by imperfections in the telescope and the rate at which different particles of light reach the telescope, is just one challenge astronomers face when they study distant exoplanets. Noise can distort observations and introduce uncertainties into the data, Zhang said. Trying to detect specific gases in distant exoplanet atmospheres introduces even more uncertainty. The most noticeable features from a gas like dimethyl sulfide stem from a bond of hydrogen and carbon molecules — a connection that can stretch and bend and absorb light at different wavelengths, making it hard to definitively detect one kind of molecule, Zhang said. 'The problem is basically every organic molecule has a carbon-hydrogen bond,' Zhang said. 'There's hundreds of millions of those molecules, and so these features are not unique. If you have perfect data, you can probably distinguish between different molecules. But if you don't have perfect data, a lot of molecules, especially organic molecules, look very similar, especially in the near-infrared.' Delving further into the paper, Luque and Zhang also noticed that the perceived temperature of the planet appeared to increase sharply from a range of about 250 Kelvin to 300 Kelvin (-9.67 F to 80.33 F or -23.15 C to 26.85 C) in research Madhusudhan published in 2023 to 422 Kelvin (299.93 F or 148.85 C) in the April study. Such harsh temperatures could change the way astronomers think about the planet's potential habitability, Zhang said, especially because cooler temperatures persist in the top of the atmosphere — the area that Webb can detect — and the surface or ocean below would likely have even higher temperatures. 'This is just an inference only from the atmosphere, but it would certainly affect how we think about the planet in general,' Luque said. Part of the issue, he said, is that the April analysis didn't include data collected from all three Webb instruments Madhusudhan's team used over the past few years. So Luque, Zhang and their colleagues conducted a study combining all the available data to see whether they could achieve the same results, or even find a higher amount of dimethyl sulfide. They found 'insufficient evidence' of both molecules in the planet's atmosphere. Instead, Luque and Zhang's team spotted other molecules, like ethane, that could fit the same profile. But ethane does not signify life. Arizona State's Welbanks and his colleagues, including Dr. Matt Nixon, a postdoctoral researcher in the department of astronomy at the University of Maryland College Park, also found what they consider a fundamental problem with the April paper on K2-18b. The concern, Welbanks said, was with how Madhusudhan and his team created models to show which molecules might be in the planet's atmosphere. 'Each (molecule) is tested one at a time against the same minimal baseline, meaning every single model has an artificial advantage: It is the only explanation permitted,' Welbanks said. When Welbanks and his team conducted their own analysis, they expanded the model from Madhusudhan's study. '(Madhusudhan and his colleagues) didn't allow for any other chemical species that could potentially be producing these small signals or observations,' Nixon said. 'So the main thing we wanted to do was assess whether other chemical species could provide an adequate fit to the data.' When the model was expanded, the evidence for dimethyl sulfide or dimethyl disulfide 'just disappears,' Welbanks said. Madhusudhan believes the studies that have come out after his April paper are 'very encouraging' and 'enabling a healthy discussion on the interpretation of our data on K2-18b.' He reviewed Luque and Zhang's work and agreed that their findings don't show a 'strong detection for DMS or DMDS.' When Madhusudhan's team published the paper in April, he said the observations reached the three-sigma level of significance, or a 0.3% probability that the detections occurred by chance. For a scientific discovery that is highly unlikely to have occurred by chance, the observations must meet a five-sigma threshold, or below a 0.00006% probability that the observations occurred by chance. Meeting such a threshold will require many steps, Welbanks said, including repeated detections of the same molecule using multiple telescopes and ruling out potential nonbiological sources. While such evidence could be found in our lifetime, it is less likely to be a eureka moment and more a slow build requiring a consensus among astronomers, physicists, biologists and chemists. 'We have never reached that level of evidence in any of our studies,' Madhusudhan wrote in an email. 'We have only found evidence at or below 3-sigma in our two previous studies (Madhusudhan et al. 2023 and 2025). We refer to this as moderate evidence or hints but not a strong detection. I agree with (Luque and Zhang's) claim which is consistent with our study and we have discussed the need for stronger evidence extensively in our study and communications.' In response to the research conducted by Welbanks' team, Madhusudhan and his Cambridge colleagues have authored another manuscript expanding the search on K2-18b to include 650 types of molecules. They have submitted the new analysis for peer review. 'This is the largest search for chemical signatures in an exoplanet to date, using all the available data for K2-18b and searching through 650 molecules,' Madhusudhan said. 'We find that DMS continues to be a promising candidate molecule in this planet, though more observations are required for a firm detection as we have noted in our previous studies.' Welbanks and Nixon were pleased that Madhusudhan and his colleagues addressed the concerns raised but feel that the new paper effectively walks back central claims made in the original April study, Welbanks said. 'The new paper tacitly concedes that the DMS/DMDS detection was not robust, yet still relies on the same flawed statistical framework and a selective reading of its own results,' Welbanks said in an email. 'While the tone is more cautious (sometimes), the methodology continues to obscure the true level of uncertainty. The statistical significance claimed in earlier work was the product of arbitrary modeling decisions that are not acknowledged.' Luque said the Cambridge team's new paper is a step in the right direction because it explores other possible chemical biosignatures. 'But I think it fell short in the scope,' Luque said. 'I think it restricted itself too much into being a rebuttal to the (Welbanks) paper.' Separately, however, the astronomers studying K2-18b agree that pushing forward on researching the exoplanet contributes to the scientific process. 'I think it's just a good, healthy scientific discourse to talk about what is going on with this planet,' Welbanks said. 'Regardless of what any single author group says right now, we don't have a silver bullet. But that is exactly why this is exciting, because we know that we're the closest we have ever been (to finding a biosignature), and I think we may get it within our lifetime, but right now, we're not there. That is not a failure. We're testing bold ideas.'

Largest celestial object of its kind discovered in the distant universe

Hashtags

Try Our AI Features

Comments

Related Articles

‘Flooding could end southern Appalachia': the scientists on an urgent mission to save lives

A surprising study revealed biological activity on a distant planet. Weeks later, scientists say there's more to the story

How one planet is revealing why it's so hard to detect life beyond Earth

Largest celestial object of its kind discovered in the distant universe

Hashtags

Try Our AI Features

Comments

Related Articles

‘Flooding could end southern Appalachia': the scientists on an urgent mission to save lives

A surprising study revealed biological activity on a distant planet. Weeks later, scientists say there's more to the story

How one planet is revealing why it's so hard to detect life beyond Earth

Get Started Now: Download the App