Latest news with #SchoolofEarthandSpaceExploration
Time of India
5 days ago
- Science
- Time of India
Hint of ‘life' beyond Earth? Study reveals ‘surprising' biological activity on a distant planet
In the age of scientific evolution, technological advancements, and space exploration, we have often pondered over this one question for years – is there any planet beyond Earth that could sustain what we know as 'life'? Any planet that might be habitable for living beings in the future? In April 2025, the scientific community was abuzz with a groundbreaking announcement: astronomers had detected dimethyl sulfide (DMS) in the atmosphere of exoplanet K2-18b, located 124 light-years from Earth. DMS is a compound produced solely by biological processes on Earth, primarily by marine phytoplankton. This discovery was hailed as the strongest evidence yet of potential extraterrestrial life beyond our solar system. However, just weeks later, scientists are urging caution and emphasizing that the initial excitement may have been premature. Why? While the detection of DMS is intriguing, it does not definitively prove the existence of life on K2-18b. The compound could also be produced by unknown non-biological processes, and further observations are needed to confirm its origin. As per Dr. Luis Welbanks, a postdoctoral research scholar at Arizona State University's School of Earth and Space Exploration, '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.' What is K2-18b? K2-18b, classified as a "Hycean" world, is a super-Earth exoplanet, meaning it's larger and more massive than Earth, that orbits a red dwarf star called K2-18. It's located about 124 light-years away from Earth in the constellation Leo. The planet is in its star's habitable zone, meaning it could potentially have liquid water on its surface, according to NASA. The exoplanet has a hydrogen-rich atmosphere and a subsurface ocean. This environment could potentially support microbial life. In addition to DMS, the James Webb Space Telescope has detected methane and carbon dioxide in the planet's atmosphere, further suggesting conditions that might be conducive to life. However, despite these promising signs and excitement surrounding the same, scientists remain cautious. The detection of DMS alone is not sufficient to confirm the presence of life. As Professor Nikku Madhusudhan, of the University of Cambridge and the lead author of the April study , noted, "We have to question ourselves both on whether the signal is real and what it means." The initial excitement surrounding the discovery of DMS on K2-18b underscores the growing interest in the search for extraterrestrial life. However, it also highlights the complexities and challenges of interpreting data from distant exoplanets. 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. However, the search for life beyond Earth continues. 'Are we really alone in this vast universe?' As scientists continue to analyze the data and conduct further observations, the prospective answers to that very question remain open. Analysis finds evidence for many exoplanets made of water and rock around small stars
Yahoo
5 days ago
- Science
- 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.'
Yahoo
6 days ago
- Science
- 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.'
CNN
31-01-2025
- Science
- CNN
Two buried ‘supercontinents' hiding inside Earth could be much older than previously thought
The mantle is a layer between Earth's thin crust and molten core. New research reveals that two 'supercontinents' hidden thousands of kilometers below the crust may serve as anchors in the mantle. Sign up for CNN's Wonder Theory science newsletter. Explore the universe with news on fascinating discoveries, scientific advancements and more. CNN — Like most of us, Earth has a lot going on under the surface — even in what may have once seemed to be its most unassuming layer. The mantle, a zone between our planet's thin crust and the molten core, features 1,800 miles (2,900 kilometers) of mostly solid rock, with a consistency like thickened caramel that scientists long hypothesized was uniformly blended. But massive unmixed regions have been found lingering in the mantle, like lumps of chocolate in a cookie, and new findings are just beginning to reveal their secrets. Among the enigmatic mantle lumps are two enormous 'supercontinents' buried thousands of kilometers below the crust amid the remains of ancient tectonic plates. One supercontinent lies under Africa, and the other resides deep under the Pacific Ocean. Using a new method to analyze data from earthquakes, researchers recently uncovered previously unknown details about these vast island regions, revealing that they may serve as anchors in our planet's mantle and that they could be much older than previously thought. The discovery adds to a growing body of evidence suggesting that the rocky mantle isn't as well-stirred by Earth's internal churning as once believed. And hidden structures or pockets of unblended material, such as these supercontinents, may shape mantle activity, including plate movement, in ways that are yet to be understood, scientists reported January 22 in the journal Nature. Related article Earth's core has slowed so much it's moving backward, scientists confirm. Here's what it could mean 'These findings will contribute to a better understanding of mantle convection and plate tectonics, and, therefore, phenomena we experience at the surface like earthquakes and volcanism,' said Claire Richardson, a doctoral candidate in the School of Earth and Space Exploration at Arizona State University, who was not involved in the new research. 'Resolving the physical, thermal, and chemical properties of rocks ~3000 km (1,864 miles) below our feet, at extreme temperatures and pressures, is a challenging problem to say the least,' Richardson told CNN in an email. 'Open questions abound, and each new study gets us closer to understanding what's really going on down there.' Clues revealed by waves Researchers first spotted the subterranean supercontinents about 50 years ago when they popped up as anomalies in seismic data generated by earthquakes powerful enough to send reverberations through the planet. When seismic waves encounter unusual structures in the mantle, changes in wave speed provide seismologists with clues about Earth's deep interior. Over the decades, seismic data revealed that these supercontinents make up about 20% of the mantle-core boundary. Each of the buried islands covers hundreds of thousands of miles, and in some spots they tower nearly 600 miles (965 kilometers) tall. However, little was known about what they were made of, when they sank and what role they might play in mantle flow, known as convection, said Dr. Sujania Talavera-Soza, lead author of the new study and a geosciences and seismology researcher at Utrecht University in the Netherlands. 'Their origin and whether they are long-lived structures — it's widely debated,' Talavera-Soza said. Earth maps in the top row show the positions of two buried supercontinents — also called large low shear velocity provinces or LLSVPs — and how they affect speed and attenuation, or damping, of seismic waves. The bottom row shows the same LLSVPs in a cross-section view of Earth. Earlier research focused on the velocity of seismic waves, showing that wave speed slowed by about 2% upon arriving at the supercontinents. This slowing of seismic waves led geologists to name the regions large low shear velocity provinces, or LLSVPs. Velocity loss in seismic waves suggested that these mantle zones were hotter than the rocks around them, Talavera-Soza said. But it was unknown whether the LLSVPs differed structurally from nearby regions. Scientists were also uncertain whether the supercontinents were actively involved in convection, or if they were 'kind of dense piles that would just be sitting there,' said study coauthor Dr. Arwen Deuss, a professor of structure and composition of Earth's deep interior at Utrecht University. 'There was no information about that,' Deuss said. 'We only knew that seismic waves slowed down.' Related article Earth's innermost layer is a 400-mile-wide ball of iron, new study suggests In the new study, the authors used a different approach for studying the LLSVPs to see if they could tease out details about the zones' composition and activity. They looked at the attenuation, or intensity, of seismic signals as they traveled through the mantle to see how much energy the vibrations from quakes lost. In music, attenuation is comparable to damping a tone, which produces a lower volume, Deuss said. Examining the attenuation of the waves — along with changes in wave speed — could provide previously unseen clues about LLSVPs' makeup. The best data for this is from waves produced by earthquakes that are magnitude 7.8 or higher, Talavera-Soza added. Wave speed and energy loss were known to be affected by mineral grain size as well as temperature, so the authors used a physics model that linked seismology and mineral physics. Waves are damped more when they encounter material made of smaller grains; if lots of grains are packed together, there are more boundaries between the grains that can sap a wave's energy. Older than 'slab graveyards' The researchers' findings could transform the understanding of plate tectonics. Here, a 7.5 magnitude earthquake leaves devastation in the Noto region of Japan's Ishikawa prefecture in January 2024. Other studies revealed that the supercontinents had company in the deep mantle. Around them were ' slab graveyards ' of sunken tectonic plates, Deuss said. They were cooler than the LLSVPs, so seismic waves moved through them more quickly. However, the new model showed that while seismic waves' velocity dipped when they reached LLSVPs, the waves didn't lose much energy. By comparison, there was significant damping among the cooler graveyards around the LLSVPs. Researchers believe those differences come down to the comparative ages of the structures. Over millions of years, as rocky material descends through the boundary between the upper and lower mantle, mineral crystals are compressed and reformed into tinier grains that then regrow over time. Younger regions therefore have smaller crystals, which suck more energy from seismic waves, so the amount of damping in a region hints at how old it is. 'The fact that the LLSVPs show very little damping, means that they must consist of much larger grains than their surroundings,' Talavera-Soza said. Larger mineral grains suggested that the supercontinents were significantly older than the tectonic graveyards around them, as their grains must have had more time to grow, according to the study. Larger building blocks would also make the supercontinents more rigid, keeping them separate from mantle convection, or movement of materials in that layer due to heat transfer. 'Our study points to the LLSVPs being long-lived features, at least half a billion years old, perhaps even older,' Talavera-Soza said. 'This implies they act as anchors at the base of the core-mantle boundary and have survived mantle convection, meaning that the mantle is not well-mixed.' Related article Hidden molten rock layer found beneath Earth's tectonic plates This discovery follows another recent revelation about even more 'sunken worlds' that contradict the notion of a blended mantle. Buried plates in tectonic graveyards tend to accumulate in alignment with Earth's subduction zones — regions where the edges of two plates meet, and where one slides beneath the other. But earlier this year, another team of scientists identified sunken tectonic slabs far from these boundaries in locations under continents' interiors and beneath oceans, where sunken plates had never been found before. 'Apparently, such zones in the Earth's mantle are much more widespread than previously thought,' said Thomas Schouten, lead author of that investigation and a researcher at the Geological Institute of ETH Zurich, the Swiss Federal Institute of Technology, in a statement. The model in the new study — the first 3D attenuation model for the entire mantle — will help seismologists to better understand what lies thousands of kilometers below Earth's surface, said Richardson, the doctoral candidate. 'It maps regions of the Earth that weaken seismic energy, ultimately affecting the measurements many seismologists use to understand other physical and chemical properties of Earth's interior,' she said. The findings could transform researchers' understanding of plate tectonics and how plate movement might be shaped by these ancient, fixed anchors near Earth's core, Deuss said. Further analysis of the supercontinents could also reveal if they are the source of geochemical elements nearly as old as Earth itself that are found in lava from certain types of volcanoes, she added. 'These LLSVPs have been there for a long time — if they've been there for a billion years, they might have also been there for 4 billion years. They might well be that hidden reservoir where these chemical primordial elements might be located. We can't prove that now, but geochemists can investigate this,' Deuss said. 'From this study, I think there will be a lot of extra research that might answer a lot of outstanding questions that have been confusing scientists for ages.' Mindy Weisberger is a science writer and media producer whose work has appeared in Live Science, Scientific American and How It Works magazine.
