Latest news with #RafaelLuque
Yahoo
5 days ago
- General
- Yahoo
Astronomers thought they found signs of life on distant planet. New studies are skeptical
Back in April, the world became captivated by the news that maybe, just maybe, we weren't alone in the universe after all. If extraterrestrials were to exist on a distant exoplanet as a team of astronomers theorized, it wouldn't exactly be intelligent life, but – hey – it was something. The explosive findings came from a team of researchers at the University of Cambridge who studied data from NASA's James Webb Space Telescope to find molecules in the atmosphere of a planet known as K2-18b that could have been created by organisms akin to marine algae. But then along came other independent astronomers who took their own look at the data and came to their own highly skeptical conclusions. A series of studies since the April 17 announcement have cast doubt on the sensational claim that what the initial researchers had found was "the strongest evidence yet" that life exists anywhere else besides Earth. "The data we have so far is much too noisy for the proof that would be needed to make that claim,' Rafael Luque, an astronomer at the University of Chicago, who led the most recent study, said in a statement. 'There's just not enough certainty to say one way or the other.' Here's everything to know about K2-18b, and just what potential it has to harbor alien life. K2-18b, which orbits a red dwarf star more than 120 light-years from Earth, has for years intrigued astronomers who believe it could be among the best places to search for signs of extraterrestrial life. The cosmic body is an exoplanet, meaning it orbits a star outside of Earth's own solar system. First discovered in 2015 during NASA's planet-hunting K2 mission, K2-18b likely orbits its star in what astronomers refer to as the "habitable zone" – where conditions could allow for water. In a nod to the classic fairy tale, astronomers even refer to these regions as "Goldilocks" zones because conditions have to be just right – neither too hot nor too cold – for water to remain in liquid form and pool on planetary surfaces. Interestingly, K2-18b, which is 8.6 times bigger than Earth, isn't rocky like our planet. Rather, observations have allowed scientists to conclude that the exoplanet could be a Hycean world covered by ocean water underneath a hydrogen-rich atmosphere. Could alien life thrive on K2-18b? What to know about the distant exoplanet The latest findings on K2-18b came from a team of researchers led by Nikku Madhusudhan, an astrophysicist at the University of Cambridge in England. Because the planet is too far and too faint to observe directly with ground telescopes, astronomers had to get creative. In this case, the team studied data from the Webb Telescope gathered from observing K2-18b as the planet crossed in front of its star, causing starlight to filter through the planet's atmosphere. As the light passed through the planet's atmosphere, different amounts of light were blocked at different wavelengths, depending on what molecules are present. That's what led Madhusudhan and his team to detect hints of sulfur-based gases dimethyl sulfide (DMS) and dimethyl disulfide (DMDS) in the atmosphere – both molecules from the same chemical family. On Earth, the gases are only produced by life, primarily microbial life such as marine algae like phytoplankton, according to the researchers. Since then, at least three different studies have largely dismissed the notion that any compelling evidence has been found to yet suggest life exists on K2-18b. In the most recent study led by Luque, researchers reviewed data from multiple observations of the planet. After combining observations of K2-18b in both the near-infrared light and longer wavelengths of mid-infrared light, the team concluded that it did not detect dimethyl sulfide. What's more, they found that other molecules, not just those possibly indicating signs of life, could explain the questionable discovery. In an earlier study published to arXiv, Jake Taylor, an astrophysicist at the University of Oxford, took a look at the Webb telescope data using a common data model for exoplanet studies and came to much the same conclusion: Taylor found no evidence of the atmospheric clues that were so integral in the Cambridge study's findings. Madhusudhan, who has issued rebuttals to some of the findings dismissing his potential discovery, has readily acknowledged that his team's observations are in need of further review. In announcing the findings, Madhusudhan conceded the molecules observed could have occurred by chance or could be the result of previously unknown chemical processes at work on K2-18b. Regardless, it appears astronomers all agree that we may not be as close as we thought to determining whether anything does indeed live on K2-18b. 'Answering whether there is life outside the solar system is the most important question of our field. It is why we are all studying these planets,' Luque said in a statement. 'We are making enormous progress in this field, and we don't want that to be overshadowed by premature declarations.' Eric Lagatta is the Space Connect reporter for the USA TODAY Network. Reach him at elagatta@ This article originally appeared on USA TODAY: Planet K2-18b life signs discovery now in doubt
USA Today
5 days ago
- Science
- USA Today
Astronomers thought they found signs of life on distant planet. New studies are skeptical
Astronomers thought they found signs of life on distant planet. New studies are skeptical A series of studies have cast doubt on the sensational claim that "the strongest evidence yet" was found that life exists anywhere else besides Earth. Show Caption Hide Caption Astronomers find possible signs of alien life on distant planet K2-18b Astronomers plan to conduct more research after finding possible signs of alien life on a distant exoplanet known as K2-18b. The findings came from a team of researchers at the University of Cambridge who studied data from NASA's James Webb Space Telescope to find molecules in the atmosphere of a planet known as K2-18b. On Earth, the gases are only produced by life, primarily microbial life such as marine algae like phytoplankton, according to the researchers. Since then, other independent astronomers who took their own look at the data and came to their own highly skeptical conclusions. Back in April, the world became captivated by the news that maybe, just maybe, we weren't alone in the universe after all. If extraterrestrials were to exist on a distant exoplanet as a team of astronomers theorized, it wouldn't exactly be intelligent life, but – hey – it was something. The explosive findings came from a team of researchers at the University of Cambridge who studied data from NASA's James Webb Space Telescope to find molecules in the atmosphere of a planet known as K2-18b that could have been created by organisms akin to marine algae. But then along came other independent astronomers who took their own look at the data and came to their own highly skeptical conclusions. A series of studies since the April 17 announcement have cast doubt on the sensational claim that what the initial researchers had found was "the strongest evidence yet" that life exists anywhere else besides Earth. "The data we have so far is much too noisy for the proof that would be needed to make that claim,' Rafael Luque, an astronomer at the University of Chicago, who led the most recent study, said in a statement. 'There's just not enough certainty to say one way or the other.' Here's everything to know about K2-18b, and just what potential it has to harbor alien life. What is exoplanet K2-18b? K2-18b, which orbits a red dwarf star more than 120 light-years from Earth, has for years intrigued astronomers who believe it could be among the best places to search for signs of extraterrestrial life. The cosmic body is an exoplanet, meaning it orbits a star outside of Earth's own solar system. First discovered in 2015 during NASA's planet-hunting K2 mission, K2-18b likely orbits its star in what astronomers refer to as the "habitable zone" – where conditions could allow for water. In a nod to the classic fairy tale, astronomers even refer to these regions as "Goldilocks" zones because conditions have to be just right – neither too hot nor too cold – for water to remain in liquid form and pool on planetary surfaces. Interestingly, K2-18b, which is 8.6 times bigger than Earth, isn't rocky like our planet. Rather, observations have allowed scientists to conclude that the exoplanet could be a Hycean world covered by ocean water underneath a hydrogen-rich atmosphere. Could alien life thrive on K2-18b? What to know about the distant exoplanet Have they found life on K2-18b? The latest findings on K2-18b came from a team of researchers led by Nikku Madhusudhan, an astrophysicist at the University of Cambridge in England. Because the planet is too far and too faint to observe directly with ground telescopes, astronomers had to get creative. In this case, the team studied data from the Webb Telescope gathered from observing K2-18b as the planet crossed in front of its star, causing starlight to filter through the planet's atmosphere. As the light passed through the planet's atmosphere, different amounts of light were blocked at different wavelengths, depending on what molecules are present. That's what led Madhusudhan and his team to detect hints of sulfur-based gases dimethyl sulfide (DMS) and dimethyl disulfide (DMDS) in the atmosphere – both molecules from the same chemical family. On Earth, the gases are only produced by life, primarily microbial life such as marine algae like phytoplankton, according to the researchers. Scientists cast doubt on signs of alien life on K2-18b Since then, at least three different studies have largely dismissed the notion that any compelling evidence has been found to yet suggest life exists on K2-18b. In the most recent study led by Luque, researchers reviewed data from multiple observations of the planet. After combining observations of K2-18b in both the near-infrared light and longer wavelengths of mid-infrared light, the team concluded that it did not detect dimethyl sulfide. What's more, they found that other molecules, not just those possibly indicating signs of life, could explain the questionable discovery. In an earlier study published to arXiv, Jake Taylor, an astrophysicist at the University of Oxford, took a look at the Webb telescope data using a common data model for exoplanet studies and came to much the same conclusion: Taylor found no evidence of the atmospheric clues that were so integral in the Cambridge study's findings. Madhusudhan, who has issued rebuttals to some of the findings dismissing his potential discovery, has readily acknowledged that his team's observations are in need of further review. In announcing the findings, Madhusudhan conceded the molecules observed could have occurred by chance or could be the result of previously unknown chemical processes at work on K2-18b. Regardless, it appears astronomers all agree that we may not be as close as we thought to determining whether anything does indeed live on K2-18b. 'Answering whether there is life outside the solar system is the most important question of our field. It is why we are all studying these planets,' Luque said in a statement. 'We are making enormous progress in this field, and we don't want that to be overshadowed by premature declarations.' Eric Lagatta is the Space Connect reporter for the USA TODAY Network. Reach him at elagatta@
Yahoo
25-05-2025
- Science
- Yahoo
Scientists question possible signs of life on exoplanet K2-18b in new study: 'We never saw more than insignificant hints'
When you buy through links on our articles, Future and its syndication partners may earn a commission. In 2023, scientists from Cambridge University reported what appeared to be very exciting news. NASA's James Webb Space Telescope, they said, had detected signs of a liquid water ocean — and possibly life — on the exoplanet K2-18b, a temperate sub-Neptune world located about 124 light-years away from Earth. Then, earlier this year, the same team announced what they called even stronger evidence for those potential signs of alien life. The signs were rooted in a tentative detection of dimethyl sulfide (DMS) — a molecule produced on Earth solely by marine life — and/or its close chemical relative DMDS, which is also a potential biosignature, in the atmosphere of the exoplanet. This finding, along with the possibility that K2-18b is a "Hycean world" with a liquid water ocean, sparked significant interest about its potential to support life. However, these results have sparked intense debate among astronomers. While recognizing this finding would be a groundbreaking achievement and a major testament to the James Webb Space Telescope's (JWST) capabilities if true, many scientists remain skeptical, questioning both the reliability of the detected DMS signature as well as whether DMS itself is a dependable sign of life in the first place. As such, many independent teams have been conducting follow-up studies about the original claims — and a newly published one only adds to the debate, suggesting the Cambridge scientists' DMS detection wasn't significant enough to warrant the publicity it received. "Among the physical sciences, astronomy enjoys a privileged position," Rafael Luque, a post doctoral researcher at the University of Chicago, told "It is more frequently covered in the media thanks to its visual appeal and the big philosophical and universal questions it addresses. It was therefore expected that — even if tentative — the detection of a potential biomarker in the atmosphere of an exoplanet would have extensive coverage." Luque and his colleagues, including fellow postdoctoral researchers Caroline Piaulet-Ghorayeb and Michael Zhang, remain unconvinced that what astronomers observed on K2-18b was in fact a credible signature indicating life. In a recent arxiv preprint — which is yet to be peer-reviewed — their team re-examined the validity of the original evidence. "This is how science works: evidence and counterevidence go hand in hand,' he stated. When scientists study data from different instruments separately, they might end up with conflicting results — it's like finding two different "stories" about a subject that don't match. "This is, in fact, what happened in the original team's papers," Zhang told "They inferred a much higher temperature from their MIRI (mid-infrared) data than from their NIRISS and NIRSpec (near-infrared) data. Fitting all the data with the same model ensures that we're not telling contradictory stories about the same planet." Thus, the team conducted a joint analysis of K2-18b using data from all three of the JWST's key instruments — the Near Infrared Imager and Slitless Spectrograph (NIRISS) and the Near Infrared Spectrograph (NIRSpec), which capture near-infrared light, and the Mid-Infrared Instrument (MIRI), which detects longer mid-infrared wavelengths. The goal was to ensure a consistent, planet-wide interpretation of K2-18b's spectrum that the team felt the original studies both lacked. "We reanalyzed the same JWST data used in the study published earlier this year, but in combination with other JWST observations of the same planet published […] two years ago," Piaulet-Ghorayeb told "We found that the stronger signal claimed in the 2025 observations is much weaker when all the data are combined." These signals may appear weaker when all data is combined because the initial "strong" detection may have been overestimated, the team says, due to being based on a limited initial data set. Combining data from multiple sources lets scientists cross-check and verify the strength — and validity — of a particular signal. "Different data reduction methods and retrieval codes always give slightly different results, so it is important to try multiple methods to see how robust the results are," explained Piaulet-Ghorayeb. "We never saw more than insignificant hints of either DMS or DMDS, and even these hints were not present in all data reductions." "Importantly, we showed that when testing a wider range of molecules that we expect to be produced abiotically in the atmosphere, the same observed spectral features can be reproduced without the need for DMS or DMDS," she continued. Molecules in an exoplanet's atmosphere are typically detected through spectral analysis, which identifies unique "chemical fingerprints" based on how the planet's atmosphere absorbs specific wavelengths of starlight as it passes — or transits — in front of its host star. This absorption leaves distinct patterns in the light spectrum that reveal the presence of different molecules. "Each molecule's signature is unique, but different molecules can have some features that fall in similar places because of their close molecular structures," explained Piaulet-Ghorayeb. The difference between DMS and ethane — a common molecule in exoplanet atmospheres — is just one sulfur atom, and current spectrometers, including those on the JWST, have impressive sensitivity, but still face limits. The distance to exoplanets, the faintness of signals, and the complexity of atmospheres mean distinguishing between molecules that differ by just one atom is extremely challenging. "It is widely recognized as a huge problem for biomarker detection, though not an insurmountable one, because different molecules do have subtly different absorption features," said Piaulet-Ghorayeb. "Until we can separate these signals more clearly, we have to be especially careful not to misinterpret them as signs of life." Beyond technical limitations, another source of skepticism is how the data has been interpreted statistically. Luque points out that the 2023 study described the detection of DMS as "tentative," reflecting the preliminary nature of the finding. However, the most recent 2025 paper reported that the detection of DMS and/or DMDS reached 3-sigma significance — a level that, while below the 5-sigma threshold required for a confirmed discovery, is generally considered moderate statistical evidence. "Surprisingly, this latest work was used to double down on the claim for DMS and even more complex molecules to be present. The detection, however, is not statistically significant nor robust, as we show in our work. Despite these uncertainties, the team is worried that media coverage has continued to spotlight bold claims about DMS and other molecules. "The [JWST] telescope is incredibly powerful, but the signals we're detecting are very small. As a community, we have to make sure that any claims we make about a planet's composition are robust to the choices made when processing the data from the telescope," said Piaulet-Ghorayeb. Related Stories: — Doubts over signs of alien life on exoplanet K2-18b are rising: 'This is evidence of the scientific process at work' — Does exoplanet K2-18b host alien life or not? Here's why the debate continues — The pursuit of truths: A letter on the boy who cried aliens (op-ed) "Researchers have the responsibility to double-check and verify, but the media is also responsible for duly reporting these follow-up works to the general public," added Luque. "Even if they have less catchy titles." "As Carl Sagan once said, 'extraordinary claims require extraordinary evidence,'" said Luque. "That threshold was not met by how the results were disseminated to the general public." Whether we'll ever get a clear answer about life on K2-18 b is uncertain — not just because of technological limits, but because the case for follow-ups with the JWST may simply not be strong enough. "JWST is continuing to observe K2-18b, and even though the new observations won't have the ability to detect life, we will soon find out more about the planet's atmosphere and interior," Zhang said.
