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The Independent
29-07-2025
- Science
- The Independent
What we know about the search for ‘Planet Nine' in our solar system
Is there a massive undiscovered planet on the outer reaches of the Solar System? The idea has been around since before the discovery of Pluto in the 1930s. Labelled as planet X, prominent astronomers had put it forward as an explanation for Uranus 's orbit, which drifts from the path of orbital motion that physics would expect it to follow. The gravitational pull of an undiscovered planet, several times larger than Earth, was seen as a possible reason for the discrepancy. That mystery was ultimately explained by a recalculation of Neptune 's mass in the 1990s, but then a new theory of a potential Planet Nine was put forward in 2016 by astronomers Konstantin Batygin and Mike Brown at Caltech (the California Institute of Technology). Their theory relates to the Kuiper Belt, a giant belt of dwarf planets, asteroids and other matter that lies beyond Neptune (and includes Pluto). Many Kuiper Belt objects – also referred to as trans-Neptunian objects – have been discovered orbiting the Sun, but like Uranus, they don't do so in a continuous expected direction. Batygin and Brown argued that something with a large gravitational pull must be affecting their orbit, and proposed Planet Nine as a potential explanation. This would be comparable to what happens with our own Moon. It orbits the Sun every 365.25 days, in line with what you would expect in view of their distance apart. However, the Earth's gravitational pull is such that the Moon also orbits the planet every 27 days. From the point of view of an outside observer, the Moon moves in a spiralling motion as a result. Similarly, many objects in the Kuiper Belt show signs of their orbits being affected by more than just the Sun's gravity. While astronomers and space scientists were initially sceptical about the Planet Nine theory, there has been mounting evidence, thanks to increasingly powerful observations, that the orbits of trans-Neptunian objects are indeed erratic. As Brown said in 2024, 'I think it is very unlikely that P9 does not exist. There are currently no other explanations for the effects that we see, nor for the myriad other P9-induced effects we see on the Solar System.' In 2018, for example, it was announced that there was a new candidate for a dwarf planet orbiting the Sun, known as 2017 OF201. This object measures around 700km across (Earth is roughly 18x bigger) and has a highly elliptical orbit. This lack of a roughly circular orbit around the Sun suggested either an impact early in its lifetime that put it on this path, or gravitational influence from Planet Nine. Problems with the theory On the other hand, if Planet Nine exists, why hasn't anyone found it yet? Some astronomers question whether there's enough orbital data from Kuiper objects to justify any conclusions about its existence, while alternative explanations get put forward for their motion, such as the effect of a ring of debris or the more fantastical idea of a small black hole. The biggest issue, however, is that the outer Solar System just hasn't been observed for long enough. For example, object 2017 OF201 has an orbital period of about 24,000 years. While an object's orbital path around the Sun can be found in a short number of years, any gravitational effects probably need four to five orbits to notice any subtle changes. New discoveries of objects in the Kuiper Belt have also presented challenges for the Planet Nine theory. The latest is known as 2023 KQ14, an object discovered by the Subaru telescope in Hawaii. It is known as a 'sednoid', meaning it spends most of its time far away from the Sun, though within the vast area in which the Sun has a gravitational pull (this area lies some 5,000AU or astronomical units away, where 1AU is the distance from the Earth to the Sun). The object's classification as a sednoid also means the gravitational influence of Neptune has little to no effect on it. 2023 KQ14's closest approach to the Sun is around 71AU away, while its furthest point is about 433AU. By comparison, Neptune is about 30AU away from the Sun. This new object is another with a very elliptical orbit, but it is more stable than 2017 OF201, which suggests that no large planet, including a hypothetical Planet Nine, is significantly affecting its path. If Planet Nine exists, it would therefore perhaps have to be farther than 500AU away from the Sun. To make matters worse for the Planet Nine theory, this is the fourth sednoid to be discovered. The other three also exhibit stable orbits, similarly suggesting that any Planet Nine would have to be very far away indeed. Nonetheless, the possibility remains that there could still be a massive planet affecting the orbits of bodies within the Kuiper Belt. But astronomers' ability to find any such planet remains somewhat limited by the restrictions of even unmanned space travel. It would take 118 years for a spacecraft to travel far enough away to find it, based on estimates from the speed of Nasa's New Horizons explorer. This means we'll have to continue to rely on ground- and space-based telescopes to detect anything. New asteroids and distant objects are being discovered all the time as our observing capabilities become more detailed, which should gradually shed more light on what might be out there. So watch this (very big) space, and let's see what emerges in the coming years. Ian Whittaker is a Senior Lecturer in Physics at Nottingham Trent University.
NDTV
28-07-2025
- Science
- NDTV
Is There Life Present On K2-18b Exoplanet? New Observations Provide Insights
A team of scientists claimed in April that a planet orbiting a distant star bore a possible signature of life, but the latest observations suggest otherwise. At the University of Cambridge, Nikku Madhusudhan and his colleagues claimed in April that they found hints of the molecules dimethyl sulphide (DMS) and dimethyl disulphide (DMDS) in the atmosphere on K2-18b using the James Webb Space Telescope (JWST) data. On Earth, these sulfur-based compounds are primarily produced by marine microorganisms. Madhusudhan said those were the "first hints we are seeing of an alien world that is possibly inhabited". K2-18b is a super-Earth located 124 light-years away in the constellation Leo. It is approximately 2.6 times the diameter and 8.6 times the mass of Earth, orbiting a cool red dwarf star within the habitable zone. What did the other researchers say? Other researchers also analysed the same data using different statistical models and didn't find evidence for the presence of these molecules. Renyu Hu at the California Institute of Technology and his colleagues teamed up with Madhusudhan and his group to analyse the observations of K2-18b. "The paper does not provide conclusive evidence for the existence of this molecule in the atmosphere," Hu said as quoted by the New Scientist. The second team found no statistical evidence.. However, Madhusudhan told New Scientist that his colleagues analysed the data again, which made him "more confident" that DMS was the best explanation. James Webb's near-infrared camera was used by the second group of researchers to look at the light coming from K2-18b's star. It can reveal what molecules exist in the atmosphere after passing through the planet's atmosphere. The camera looked at a different wavelength of light compared to the mid-infrared measurements that were used for the analysis done in April. "This model dependency just speaks to the fact that it is a very weak signal, if there is any signal at all," Hu said. "I would just exercise caution". "This paper is very clear in saying that there is no evidence for dimethyl sulphide. There is no statistical evidence for any of these gases," Luis Welbanks at Arizona State University said as quoted. "We seem to be coming to the end of the debate on whether DMS is present in detectable levels in the [K2-18b] atmosphere, as the increased precision has not helped to detect it at a higher significance," Jake Taylor at the University of Oxford said, as quoted. Scientists previously proposed that K2-18b could be a "Hycean world," a planet with a hydrogen-rich atmosphere and vast ocean, making it a prime candidate for hosting life. Hu and his team found that for certain hydrogen-rich atmospheres, chemicals can produce DMS without the presence of life. "A key takeaway is that biosignatures are going to be hard, no matter what kind of planet we are talking about," Jacob Bean, an astronomer at the University of Chicago, who was not involved in the study, said as quoted by The New York Times. All researchers, however, agreed that the planet is rich in water. Strong evidence for the presence of methane and carbon dioxide was also found by Hu and his team. It implies the existence of water, Hu said. However, additional studies could provide insights into the planet's atmospheric composition, temperature profile and potential biosignatures.
The Hindu
28-07-2025
- Science
- The Hindu
New microscope reveals molecular jostling faster than ever before
More than a century ago, a 26-year-old Albert Einstein explained Brownian motion in one of four papers he published in his annus mirabilis, the miraculous year, called because these papers shot him to fame. Brownian motion is the random jittering of small particles in a fluid, caused because they're constantly colliding with molecules around them. Now, scientists at the California Institute of Technology (Caltech) have developed a breakthrough imaging technique that enables real-time filming of these molecular motions. Their findings were published in Nature Communications. 'Surreal experience' Conventional microscopes are invasive and have limited fields of view. Other microscopes still can't distinguish individual molecules, which are around tens of angstroms in size (1 angstrom = 0.0000000001 m). To compare, one human hair is about a million angstrom thick. The Caltech team has now found a way to indirectly detect molecules by observing their interactions with light. Their technique also taps into the Brownian motion of particles. Using the device they have reported that they can see down to tens of angstroms. 'It was a surreal experience to visualise molecular sizes in real-time at the angstrom scale,' Yogeshwar Nath Mishra, who co-led the study when at Caltech's Jet Propulsion Laboratory and who is now an assistant professor at IIT-Jodhpur, said. 'Even more remarkable was the realisation that no existing technique can achieve this level of detail.' Need for speed The more massive a particle, the slower its Brownian motion. '[It] is like watching how much a spinning object twists after being nudged by light. Small molecules spin fast and scramble the light more. Big molecules spin slowly and keep it aligned,' Lihong Wang, director of the Caltech Optical Imaging Laboratory and who supervised the study, said. So by measuring how fast a molecule changes the properties of light, they could determine its size. The Egyptian-American chemist Ahmed Zewail from Caltech was the first to measure particle motion at super-short time scales. This work allowed his team to observe chemical reactions as they happened for the first time. He was awarded the Nobel Prize for chemistry in 1999. 'While traditional techniques often rely on time-consuming point-by-point scanning, our approach captures the scene in a single shot,' Wang said. 'We also achieved imaging speeds of hundreds of billions of frames per second, making it possible to observe molecular interactions in unprecedented slow motion.' The device is thus the world's fastest single-shot microscope. 'Finally, unlike [traditional methods] which require extensive sample preparation and often damage the specimen, our method is non-intrusive, enabling direct, in-situ measurements,' Wang added. 'Some of the most exciting features of this microscope include its wide-field imaging capability, offering an image area of a few square centimetres, an order of magnitude larger than conventional microscopes,' per Mishra. 'To the best of our knowledge, our work is the first ever to achieve the feat of single-shot 2D molecular sizing.' Playing jigsaw They tested their microscope using a molecule called fluorescein-dextran. Fluorescein is a food colouring dye. Fluorescein-dextran is used to monitor blood flow, drug delivery, and tissue and cell labelling. These fluorescent molecules come in the form of powders. The scientists blended them with water and used clean pipettes to pour drops of these samples into cuvettes (clear, short, rectangular tubes for holding liquid samples). Then they turned to ultrashort pulses from a laser. These lasers aren't unlike those used in LASIK and cataract surgeries. The laser sheet slices through the sample in the cuvette. As it does, the sample emits light that falls on an array of small square mirrors making up a digital micromirror device (DMD). The DMD's job is to shape the light beam. Researchers use software code to tilt each individual mirror in this light-crafter depending on the corresponding pixel in the input image. 'Imagine you're trying to solve a jigsaw puzzle, but instead of having all the pieces, you only have a few of them — and surprisingly, you can still figure out what the full picture looks like,' Wang said. This idea underpins the team's technique, which can reconstruct the full picture from very few measurements provided the structure is repetitive. The DMD converts the transient scene into a random jigsaw pattern from which researchers can extract information about the full picture. The light finally passes through a streak tube that converts the photons in light to electrons. A phosphor screen collects these electrons as they sweep across it and creates a pattern of streaks. The streak pattern reveals the pulse duration from which scientists can infer the sizes of the molecules. Ensemble of molecules 'It is an interesting piece of work. The key in this work is the use of the streak camera to detect dynamics in nanoseconds. This is within the actual lifetimes of the molecules and wouldn't be possible with slow detectors or photodetectors,' Basudev Roy, an associate professor at IIT Madras who works on super-resolution microscopy and wasn't involved in the recent study, said. The size of molecules measured using their technique concurred with previous estimates. 'It still sees an ensemble of molecules inside a detection region — it still doesn't see a single molecule yet. But the dynamics indicate chemical compositions and also chemical reactions,' Roy said. 'Surprisingly, we found out that the technique also works in gas phases. … Initially, we assumed it would be challenging to apply [it] in turbulent environments, such as within a flame,' said study co-lead Peng Wang of Caltech. The team observed black carbon nanoparticles in flames through the microscope. 'Our data in the gas phase turned out to work excellently and the molecule size matches … experimental observation well,' Peng said. This new imaging technique could help better visualise processes and transform biomedical research, disease detection, drug design, and nanomaterial fabrication, among others. Unnati Ashar is a freelance science journalist.
Boston Globe
08-07-2025
- Science
- Boston Globe
Franklin W. Stahl, 95, dies; helped create a ‘beautiful' DNA experiment
Dr. Stahl's name and that of his collaborator, Matthew Meselson, were immortalized by the Meselson-Stahl Experiment, which is referenced in biology textbooks and taught in molecular genetics courses worldwide. In 2015, 'Helix Spirals,' a musical tribute to the experiment, was composed by Augusta Read Thomas and performed by a string quartet in Boston. Get Starting Point A guide through the most important stories of the morning, delivered Monday through Friday. Enter Email Sign Up The two biologists proved a theory advanced by Nobel Prize winners James Watson and Francis Crick, who discovered DNA's helical structure in 1953. Watson and Crick posited in the journal Nature that DNA replicates in a so-called semi-conservative fashion. Advertisement In 1958, Meselson and Dr. Stahl, postdoctoral fellows in Linus Pauling's laboratory at the California Institute of Technology in Pasadena, proved that Watson and Crick were correct, by using an experiment that was celebrated for its design, execution, and results. 'It has been termed the most beautiful experiment in biology, and rightfully so,' Diana Libuda, an associate professor of biology at the University of Oregon and a member of the Institute of Molecular Biology there, said in an interview. Advertisement The experiment demonstrated that after DNA unwinds and is replicated, each new DNA molecule contains one original, or parental, strand and one newly copied strand. Dr. Stahl and Meselson proved this by using E. coli bacteria, which reproduce rapidly. Because nitrogen is a crucial component of DNA, the two scientists propagated the bacteria over multiple generations in a medium containing heavy nitrogen, which was absorbed by the bacteria and integrated into their DNA. The bacteria were subsequently transferred to a medium containing the normal isotope of nitrogen. With the two types of nitrogen now in the medium, Dr. Stahl and Meselson could trace the production of new DNA strands. The experiment provided powerful evidence that DNA is replicated semi-conservatively, which means that each new DNA molecule is a hybrid, composed of one old strand and one newly made strand. That finding was considered a landmark discovery. Their results were published in Proceedings of the National Academy of Sciences in 1958. The Meselson-Stahl experiment has since been praised as a model of simplicity and innovation. 'Watson and Crick had produced a pretty model, but had no hard data,' Andy Stahl said. 'But that's what the Meselson-Stahl Experiment did: It proved how DNA replicates.' In 2020, Meselson, an emeritus professor of molecular biology and genetics at Harvard University, discussed each of the experiment's steps in a video produced by iBiology, part of the nonprofit Science Communication Lab in Berkeley, Calif. Reminiscing in the video about the intellectual freedom at Caltech in the late 1950s, Meselson recalled an era of big ideas: 'We could do whatever we wanted. It was very unusual for such young guys to do such an important experiment. We had a wonderful house, a big house across the street from the lab. We talked about these experiments at almost every dinner. So we had this wonderful intellectual atmosphere.' Advertisement In the same video, Franklin Stahl marveled that he and Meselson had been able to achieve such definitive results. He noted that X-ray images of the centrifuged test medium unequivocally revealed the bands of DNA with light and heavy nitrogen, proving the helical molecule's semi-conservative replication. 'Most of the time, when you get an experimental result it doesn't speak to you with such clarity,' he said. 'These pictures of the DNA bands interpreted themselves.' Franklin William Stahl was born Oct. 28, 1929, in Needham. He was the only son of Oscar Stahl, who worked for the telephone company and fixed radios on the side to earn extra cash during the Great Depression, and Elinor (Condon) Stahl, who managed the home while Franklin and his sisters attended local schools. 'He wanted to go to Brown, but went to Harvard instead,' Andy Stahl said. 'He was a commuter student and could save money by living at home.' Franklin Stahl graduated from Harvard in 1951 with a bachelor's degree in biology. Later that year, he entered the University of Rochester, where he began work on a doctoral degree. He decided to specialize in genetics in 1952 after completing a short course at Cold Spring Harbor Laboratory, where he was introduced to bacteriophages, the viruses that infect bacteria. Also known simply as phages, the viruses are reliable tools in genetics and have been used to understand the genetic code and provide insight into how genes are regulated. Advertisement In Rochester, Dr. Stahl met Mary Morgan, a native of the city. They soon married, and she eventually became a research partner. Mary Morgan Stahl died in 1996. Dr. Stahl's research collaborator and former graduate student Henriette Foss then became his domestic partner; she died of Parkinson's disease in 2022. In addition to his son Andy, Dr. Stahl leaves a daughter, Emily Morgan, and eight grandchildren. Another son, Joshua Stahl, died in 1998. Dr. Stahl also had a prolific career as an author. He wrote 'The Mechanics of Inheritance,' published in 1964, and 'Genetic Recombination: Thinking About It in Phage and Fungi' in 1979. He was the recipient of two Guggenheim fellowships, one in 1975 and the other in 1985, the same year he was awarded a MacArthur fellowship. In 1996, Dr. Stahl received the Thomas Hunt Morgan Medal, an award given to scientists who have made major contributions to the field of genetics. This article originally appeared in
Yahoo
17-06-2025
- Science
- Yahoo
Half of ordinary matter in universe has long been 'missing.' Astronomers just found it.
Astronomers have long estimated that ordinary matter – basically, anything other than dark matter – makes up only a fraction of the known universe. The conclusion stemmed from a complex calculation involving observed light left over from the Big Bang roughly 13.8 billion years ago. But there was one major problem: they had no clue where about half of it was. Now, it seems as if a team of astronomers has finally tracked down that missing "ordinary" matter, which they discovered hiding as gas spread out in the vast expanses between galaxies. Revelations made possible by studying radio waves hurtling through space suggest that violent cosmic forces have played a role in the remote locations of almost all of the "missing" matter. "The question we've been grappling with was: Where is it hiding? The answer appears to be: in a diffuse wispy cosmic web, well away from galaxies," Harvard University astronomy Liam Connor, lead author of the study, told Reuters. Ordinary matter makes up everything from the cosmic (planets and stars) to the earthly (people and trees.) But it only accounts for about 15% of matter in all of the known universe. The vast majority of matter is dark – invisible until it is detected only through its gravitational effects. Unlike dark matter, ordinary matter emits light in various wavelengths, which allow it to easily be seen. Still, scientists have long struggled to account for where all of it is located since a large chunk of ordinary matter is spread so thin among galaxies and the vast spaces between them. For that reason, about half of ordinary matter has long been considered missing. Until now. Powerful bursts of radio waves emanating from 69 locations in the cosmos have helped researchers at long last find the missing matter. The discovery came from a team of astronomers at the California Institute of Technology and the Center for Astrophysics, a research institute jointly operated by the Harvard College Observatory and Smithsonian Astrophysical Observatory. The team studied brief, bright radio flashes in the distant cosmos, called fast radio bursts (FRBs), to illuminate the matter lying between the radio waves and Earth. Astronomers have been studying fast radio bursts from across the universe since 2007 when the first millisecond-long burst was discovered. The bright burst of electromagnetic radiation may be brief, but fast radio bursts are so powerful that they produce more energy than what our sun emits in an entire year, astronomers say. The 69 radio frequencies the team studied were located at distances ranging up to about 9.1 billion light-years from Earth – making the furthest one the most distant fast radio burst ever recorded. The previous record was a fast radio burst documented about 8 billion light-years away in 2023. By measuring how the light from the radio bursts spread and dispersed – not unlike how a prism turns sunlight into a rainbow – while traveling toward Earth, the astronomers were able to determine how much matter was in their path. "If you see a person in front of you, you can find out a lot about them," Vikram Ravi, a Caltech astronomer who coauthored the study, said in a statement. "But if you just see their shadow, you still know that they're there and roughly how big they are." The results revealed that about 75% of the universe's ordinary matter resides in the space between galaxies, also known as the intergalactic medium. How did it all end up in the middle of nowhere? Astronomers theorize it happens as gas is ejected from galaxies when massive stars explode in supernovas, or when supermassive black holes inside galaxies expel material after consuming stars or gas. The remaining 15% of the "missing" matter exists within either galaxies in the form of stars and cold galactic gas, or in the halos of diffuse material around them, according to the researchers. While this distribution is in line with predictions from advanced cosmological simulations, this is the first time it has been observed and confirmed, the researchers claim. The findings will help researchers better understand how galaxies grow. Caltech is also planning for its future deep-space radio telescope in the Nevada desert, the DSA-2000, to build upon the findings when it becomes operational. The radio array is being planned to detect up to 10,000 fast radio bursts per year. The findings were published June 16 in the journal Nature. Contributing: Reuters Eric Lagatta is the Space Connect reporter for the USA TODAY Network. Reach him at elagatta@ This article originally appeared on USA TODAY: Astronomers just found the universe's 'missing' matter: Here's how
