Category: 7. Science

Researchers at Beijing University of Chemical Technology (BUCT) and BOE Technology Group Co., Ltd. (BOE) have developed a novel type of transparent organic–inorganic hybrid photoresist with highly tunable refractive index. The study published in Engineering presents the synthesis of transparent photoresist made of titanium dioxide nanoparticle-embedded acrylic resin with a tunable refractive index of up to 2.0 (589 nm) after being cured by ultraviolet (UV) light, while maintaining both a high transparency of over 98% in the visible light range and a low haze of less than 0.05%. The precision machining of optical microstructures can be imprinted easily and efficiently using the hybrid resin, which acts as a light guide plate to guide the light from the side to the top in order to conserve the energy of the display device.

In recent years, with the rapid development of electronic technology, the display devices have been used in all aspects of life. Optical materials are capable of controlling and regulating light and form the basis of optical devices, which have wide applications in fields such as flat panel display, lens, smart wearable, and augmented reality (AR)/virtual reality (VR) display. The refractive index is the basic property of optical materials and it is generally accepted that components made of optical resin with a relatively high refractive index are smaller, lighter, and have wider applicability than those made of ordinary optical materials for the same focal length requirements. Currently commercialized organic optical materials, such as epoxy resins, polymethyl methacrylate, polycarbonate, polystyrene, and silicone resins, are limited by the structural properties of the organic molecules and polymer chains, and the refractive index of the materials is in the range of 1.4–1.6. To tune the refractive index of UV-curable resin, researchers have tried to add inorganic nanoparticles with high refractive index into the acrylic resin. According to the structural characteristics and application conditions of organic–inorganic hybrid photoresist in optoelectronic display device, the work published in Engineering focused on the optimization of titanium dioxide nanoparticle-embedded acrylic resin. The refractive index of hybrid photoresist reaches 1.67 at 589 nm when the titanium dioxide content is 30 wt% in the hybrid film, while the refractive index of pure resin is only 1.53. The researchers tested the hybrid material by using electron microscopy imaging and atomic force microscopy analysis. It is confirmed that the titanium dioxide nanoparticles can be uniformly dispersed in the composite material and the hybrid film exhibits outstanding flatness and a roughness of only 0.196 nm. To bring newly developed nanotechnology and nanocomposites with excellent performance out of the laboratory and transform them into new device products, the joint research group of BUCT and BOE has applied the organic–inorganic hybrid photoresist for precision machining of optical microstructures as the light guide plates for flat-panel display devices.

The researchers also developed light-curable resins with an ultrahigh refractive index of 2.0 (589 nm) via a change of the basic polymer material and in the amounts of titanium dioxide nanoparticles. They are also interested in using their material for various applications. The knowledge obtained from both laboratory and commercial experiments on photon regulation at various nanoscale and microscale interfaces is expected to assist in the promotion of human health via high-precision medical, lighting, and new display products.

The paper “A Transparent Photoresist Made of Titanium Dioxide Nanoparticle-Embedded Acrylic Resin with a Tunable Refractive Index for UV-Imprint Lithography,” authored by Yinglu Liu, Dan Wang, Changlin Liu, Qianqian Hao, Jian Li, Jie-Xin Wang, Xiuyun Chen, Peng Zhong, Xibin Shao, Jian-Feng Chen. Full text of the open access paper: https://doi.org/10.1016/j.eng.2023.12.014. For more information about the Engineering, follow us on Twitter (https://twitter.com/EngineeringJrnl) & like us on Facebook (https://www.facebook.com/EngineeringJrnl).

The findings, published in the journal Archaeological and Anthropological Sciences, suggest that the women likely worked in the mine, extracting stone for tools and weapons.

According to scientists, the women were likely sisters. Their skeletons were found in the mine, one buried on top of the other.

The younger woman was buried at a depth of about 6 meters, the older one about a meter lower. Both were about 1.5 meters tall and aged between 30 and 40 years. Their bones show signs of hard physical labor: worn joints, early signs of arthritis, herniated discs, and partially healed fractures.

The burial site also contained the remains of a newborn child and a dog, possibly indicating a symbolic or ceremonial purpose. Although the skeletons showed no obvious signs of violent death or disease, the researchers suggest that the circumstances of their burial may have resulted in a ritual act or a socially motivated decision.

Earlier, rare Paleolithic artifacts were uncovered at Ulukoy Cave in Türkiye, revealing the earliest known human presence in northern Mesopotamia.

In a groundbreaking breakthrough, scientists at the Max Planck Institute for Nuclear Physics in Germany have recreated one of the first chemical reactions to occur after the Big Bang: the formation of helium hydride ion (HeH⁺), believed to be the universe’s first molecule. This experiment mimics conditions from more than 13 billion years ago and provides a clearer understanding of the chemical pathways that laid the foundation for star formation. By simulating these ancient reactions in the lab, researchers are helping to unravel the mysteries of the cosmos’ earliest moments.

Universe’s first molecule and why it matters

Helium hydride (HeH⁺) is a simple molecule formed from a neutral helium atom and a positively charged hydrogen nucleus (a proton). It likely formed just after the recombination era, about 380,000 years after the Big Bang, when atoms first stabilized and the universe became transparent to radiation. Though short-lived, HeH⁺ played a vital role in the cooling of primordial gas clouds, a key step in enabling gravitational collapse, the process that forms stars. Without these early molecules acting as coolants, the birth of stars and galaxies would have been significantly delayed or even altered.

How scientists simulated the early universe

To recreate these ancient conditions, researchers employed the Cryogenic Storage Ring (CSR) in Heidelberg, a highly specialized instrument designed to simulate space-like environments. This 35-meter-diameter facility allows ions to circulate in an ultra-cold, vacuum-controlled environment, mimicking the near-zero temperatures of deep space. The team introduced HeH⁺ ions and bombarded them with a beam of neutral deuterium atoms (a hydrogen isotope with one proton and one neutron). This reaction formed HD⁺ (a deuterium-based analog to H₂⁺), closely simulating the early-universe chemistry that led to the creation of molecular hydrogen (H₂), the most abundant molecule in the universe today.

Defying theoretical predictions on molecular cooling

What surprised scientists was how efficient the reaction remained even at extremely low temperatures, contrary to long-held theoretical models. Earlier calculations had predicted a steep decline in reaction rates at near-zero temperatures, suggesting that HeH⁺ would be an insignificant player in the chemical evolution of the early cosmos. However, the experiment proved otherwise. The reaction was swift and showed no energy barrier, indicating it likely played a much greater role in dissipating heat from early gas clouds than previously thought. Theoretical physicists working alongside the experimental team also uncovered a critical flaw in earlier calculations, reinforcing the significance of the new results.

Rewriting the chemistry of the cosmic dark ages

After the universe cooled and neutral atoms formed, it entered a period known as the “cosmic dark ages,” a time with no stars, no galaxies, and no visible light, only vast clouds of hydrogen and helium. During this time, molecular interactions like those involving HeH⁺ and H atoms were some of the few active chemical processes. These reactions laid the groundwork for the eventual formation of H₂, a molecule essential for radiative cooling and thus the gravitational collapse of gas clouds into stars. The new study suggests that HeH⁺ may have had a far more active and longer-lasting presence during this era than once believed.

Broader implications for star formation and cosmology

The results of this experiment have far-reaching consequences beyond HeH⁺ itself. By showing that barrierless, efficient reactions occurred under primordial conditions, the study enhances our understanding of how molecular hydrogen and its isotopic variants (like HD⁺) came into being and how they facilitated early star formation. This could help refine astrophysical models that simulate the formation of the first stars (Population III stars), galaxies, and ultimately the structure of the universe as we see it today. It also sheds light on the chemical evolution of the interstellar medium, where similar reactions continue to occur.

A major step in reconstructing the universe’s origins

By successfully reproducing the earliest molecular reaction known to science, this experiment represents a major stride in astrochemistry and cosmology. It demonstrates how precise laboratory conditions on Earth can recreate moments from the dawn of the universe, helping scientists build a clearer picture of how matter evolved from chaos into complexity. With improved theoretical models and cutting-edge instrumentation, we are now better equipped than ever to answer some of the universe’s oldest questions, including how the very first stars came to shine in the cosmic darkness.

HONG KONG, Aug. 4, 2025 /PRNewswire/ — A collaborative research team led by Hong Kong Baptist University (HKBU) has developed a multifunctional nanorobot equipped with silver and gold nanorods to facilitate high-performance pollutant degradation and bacteria elimination, with its mobility navigated by the application of magnetic fields. The invention holds potential for broad applications in antibacterial treatments, sewage management, and biomedicine.

Chemical pollution, pathogenic bacteria, and biofilms (a community of microorganisms embedded in a slimy matrix) pose significant threats to public health. In response, scientists have developed various nanoplatforms with catalytical and antibacterial properties. However, creating a remotely controllable nanorobot with precise targeting and propulsion capabilities, which aims to enhance efficacy and flexibility in treatment strategies, remains a challenge. 

Professor Ken Leung Cham-fai, Associate Professor of the Department of Chemistry at HKBU, in collaboration with scientists from the University of Science and Technology of China, Hefei University of Technology, and the Dongcheng branch of the First Affiliated Hospital of Anhui Medical University, have designed and fabricated a nanorobot, which demonstrates capabilities in breaking down organic pollutants, exhibits antibacterial properties, and removes biofilms. The research findings have been published in the academic journal Advanced Healthcare Materials.

The multifunctional nanorobot has a hollow spherical structure with the following components and features:

• The core composes of iron oxide, a magnetic material that enables control of the nanorobot’s movement with the application of magnetic fields, so that the nanorobot can navigate along predetermined paths;
• The middle layer consists of silver and gold bi-metallic nanorods, which act as catalyst for chemical reactions that facilitate the degradation of organic pollutants, and inhibit the growth or disrupt the function of bacterial cells;
• The outer layer is made of polydopamine, a biocompatible material that protects and stabilises the inner components; and
• A large cavity and mesoporous structure that can be used as drug carriers.

To test the efficacy of the nanorobot in pollutant degradation, the research team created simulated miniature wastewater pools. Driven by magnetic fields, the nanorobots accurately moved to two of the chambers and stayed there for one minute. Subsequent tests showed that the levels of both 4-nitrophenol, an organic pollutant from industrial and agricultural activities, and methylene blue, an organic dye typically found in industrial wastewater, were reduced significantly.

The research team also discovered that the nanorobot demonstrates antibacterial capability. The team used the nanorobot loaded with zinc phthalocyanine to investigate the antibacterial effects of silver and gold on Escherichia coli and Staphylococcus aureus under various conditions, including controlling the nanorobots’ movement with magnetic fields, and applying light sources including near-infrared laser and xenon lamp irradiation. When magnetic fields, near-infrared laser and xenon lamp irradiation were applied together, the nanorobot loaded with zinc phthalocyanine achieved up to 99.99% inhibition of bacterial proliferation.

The magnetic propulsion capability of the nanorobot loaded with zinc phthalocyanine also enables it to effectively remove bacterial biofilms. When the nanorobots were introduced to biofilms grown in experiment plates, and U-shaped tubes with magnetic fields and light source were applied, they effectively disrupted and removed biofilms. When magnetic fields, near-infrared laser and xenon lamp irradiation were applied together, the most significant biofilm removal and lowest bacterial survival rates were recorded. The study highlights the potential of the nanorobot in addressing biofilm-associated infections and blockages in confined spaces like catheters.

Professor Ken Leung Cham-fai said: “Our research results show that the multifunctional nanorobot developed by our research team exhibits precise catalytic capabilities, high antibacterial activity, and effective biofilm removal properties. Its mobility navigated by magnetic fields enables pollutant degradation and antibacterial activities to be conducted in a controlled, precise and effective manner. This multifunctional nanorobot possesses significant potential for applications in sewage treatment, biomedicine, and other fields.”

SOURCE Hong Kong Baptist University

You say potato, I say tomato?

It turns out that one helped create the other: Natural interbreeding between wild tomatoes and potato-like plants in South America gave rise to the modern-day potato around 9 million years ago, according to a new study published Thursday in the journal Cell.

Co-author Loren Rieseberg, a professor at the University of British Columbia, told Agence France-Presse (AFP) the findings point to a “profound shift” in evolutionary biology, as scientists increasingly recognize the role of ancient hybridization events in shaping the Tree of Life.

While it was once thought that random mutations were by far the most significant driver of new species, “we now agree that the creative role of hybridization has been underestimated,” he said.

Simple, affordable and versatile, the humble potato is now one of the world’s most important crops. But its origins have long puzzled scientists.

Modern potato plants closely resemble three species from Chile known as Etuberosum. However, these plants do not produce tubers – the large underground structures, like those found in potatoes and yams, that store nutrients and are the parts we eat.

On the other hand, genetic analysis has revealed a surprising closeness to tomatoes.

“This is known as discordance, and indicates something interesting is going on!” co-author Sandra Knapp, a research botanist at Britain’s Natural History Museum, told AFP.

To solve the mystery, an international team of researchers analyzed 450 genomes from cultivated potatoes and 56 wild potato species.

Lead author Zhiyang Zhang, of the Agricultural Genomics Institute at Shenzhen, said in a statement: “Wild potatoes are very difficult to sample, so this dataset represents the most comprehensive collection of wild potato genomic data ever analysed.”

‘Wow’ moment

The analysis revealed that modern potatoes carry a balanced genetic legacy from two ancestral species – roughly 60% from Etuberosum and 40% from tomatoes.

“My wow moment was when the Chinese team showed that ALL potatoes, wild species as well as land races, had the same proportion of tomato genes and Etuberosum genes,” said Knapp.

“That really points to an ancient hybridization event rather than various events of gene exchange later on,” she added. “It is so clear-cut! Beautiful.”

One gene, called SP6A, which acts as a signal for tuberization, originated from the tomato lineage. But it only enabled tuber formation when paired with the IT1 gene from Etuberosum, which controls underground stem growth.

The divergence between Etuberosum and tomatoes is thought to have begun 14 million years ago – possibly due to off-target pollination by insects – and was completed 9 million years ago.

This evolutionary event coincided with the rapid uplift of the Andes mountain range, providing ideal conditions for the emergence of tuber-bearing plants that could store nutrients underground.

Another key feature of tubers is their ability to reproduce asexually, sprouting new buds without the need for seeds or pollination. This trait enabled them to spread across South America and, through later human exchange, around the world.

Co-author Sanwen Huang, a professor at the Agricultural Genomics Institute at Shenzhen, told AFP that his lab is now working on a new hybrid potato that can be reproduced by seeds to accelerate breeding.

This study suggests that using the tomato “as a chassis of synthetic biology” is a promising route for creating this new potato, he said.

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It vanished without a trace more than 10 years ago — now, a single snapshot from a trail camera has reignited hope for a species thought to be lost.

In 2024, conservationists at Tangkulap Forest Reserve set up trail cameras to survey an endangered native species of wildcat. When there was a photo of an unidentified species, it was cast aside as irrelevant to the study. 

The photo was later unearthed by Panthera researchers in collaboration with the Malaysian Otter Network — upon which the significance of the image was discovered. 

The photo from the trail camera had actually captured Malaysia’s first image of the Eurasian otter in 11 years. 

These otters can be found from Europe to Asia, although “its presence in Southeast Asia is largely unknown and extremely rare, and it’s considered highly endangered,” Panthera detailed in a blog post.

Panthera elaborated on the importance of this photo, stating that Tangkulap Forest Reserve is now “the only location in Malaysia where all four of the country’s otter species coexist.”

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The news excited conservationists. In a Facebook post, Panthera described it as “a historic moment.” One commenter said: “That’s an incredible find.”

According to Panthera’s blog, “otters are apex indicators of waterway health, and their return is a hopeful sign.” 

Trail cameras are used globally to identify and locate animals, often capturing rare sightings and unique moments. The technology allows for the observation of animal populations for long periods of time without direct interference, reducing the risk of human-animal conflict. Human-animal interactions can have dire consequences for both human and animal — danger of attack, disturbance of habitat, or decreasing the animals’ natural instincts. 

Using captured photos is an amazing way to measure a site’s biodiversity and the health of the local ecosystem — here, the sighting of a long-lost endangered species encourages the hopes of conservationists for a cleaner, more diverse future for the Tangkulap Forest Reserve.

This can empower the local community and beyond to continue to take steps toward conserving natural areas and resources.

Although this discovery brings optimism to the conservation cause, all four species of otters still remain under threat from pollution, habitat fragmentation, and overfishing.

These threats are difficult to combat. However, there are organizations fighting for real-world solutions, such as “reducing conflict between people and otters and creating a national plan to protect them before it’s too late,” as Panthera noted.

Join our free newsletter for good news and useful tips, and don’t miss this cool list of easy ways to help yourself while helping the planet.

Out there in the Universe, black holes abound.

Most are relatively low-mass: just a few solar masses.

When the two arms of an optical interferometer are of exactly equal length and there is no gravitational wave passing through, the signal is null and the interference pattern is constant. As the arm lengths change, the signal is real and oscillatory, and the interference pattern changes with time in a predictable fashion. This technique is what is used to directly reveal the presence of gravitational waves.

However, supermassive varieties, at millions or billions of solar masses, exist within galaxies.

The three different sets of approaches to gravitational waves, ground-based laser interferometers, space-based laser interferometers, and pulsar timing arrays, are all sensitive to different classes of gravitational wave signals. While LIGO was the first collaboration to detect gravitational waves at very high frequencies, the NANOGrav collaboration sees strong evidence at very low (nanohertz) frequencies. Pulsar timing is one of the best methods for probing the longest-wavelength gravitational waves of all, produced primarily by the heaviest orbiting supermassive black hole pairs.

Too massive for LIGO to see, they require longer-baseline gravitational wave detectors.

The image above shows an illustration of the three future LISA, or Laser Interferometer Space Antennae, spacecraft, in a trailing orbit behind the Earth. LISA will be our first space-based gravitational wave detector, sensitive to objects thousands of times as massive as the ones LIGO can detect. An array of LISA detectors set up at various points in Earth orbit would be able to detect even merging supermassive black holes: a proposal known as Big Bang Observer.

LISA, the proposed Big Bang Observer, or pulsar timing arrays could observe them directly.

This illustration shows how many pulsars monitored in a timing array could detect a gravitational wave signal as spacetime is perturbed by the waves. The longest-wavelength gravitational waves, such as the ones produced by the most massive pairs of merging black holes, are only detectable by methods leveraging extremely long baselines, such as pulsar timing arrays. In a similar fashion, a precise enough laser array could, in principle, detect the quantum nature of gravitational waves.

Galactic mergers bring multiple supermassive black holes together, leading to inspirals, mergers, and ringdowns.

The messy cores of these colliding galaxies hide the final stage of two merging galactic nuclei. The right-hand images for these five galaxies show close-ups in infrared light of the galactic cores, which clearly show the presence of two separate black holes. Over enough time, these black holes will all merge together, where the final stages of the merger will be due to the emission of gravitational waves until their event horizons contact one another, leading to a merger and ringdown.

The heaviest binary supermassive black hole is OJ 287, discovered in 1887.

The most massive pair of black holes in the known Universe is OJ 287, whose gravitational waves will be so long in wavelength that they’ll even be out of reach of LISA. A longer-baseline gravitational wave observatory could see it, as could, potentially, a sufficiently precise pulsar timing array. Although OJ 287 was first imaged in 1887, its nature and distance were not determined until the 1960s.

Located ~4 billion light-years away, black holes of 150 million and ~18 billion solar masses orbit one another.

This diagram shows the relative sizes of the event horizons of the two supermassive black holes orbiting one another in the OJ 287 system. The larger one, of ~18 billion solar masses, is 12 times the size of Neptune’s orbit; the smaller, of 150 million solar masses, is about the size of the asteroid Ceres’s orbit around the Sun. The heaviest known black hole is only a few times more massive (and hence, a few times larger in radius) than OJ 287’s primary.

Every 11-12 years, they complete one orbit.

The double peaks of the flare seen from OJ 287 is consistent with the smaller black hole punching through the larger’s accretion disk twice per orbit. The rate of the flaring, plus time-based changes in the flare’s orientation, are thoroughly predictable with Einstein’s general relativity alone.

Due to general relativity, their orbits precess substantially: by 39° per revolution.

This animation shows a lower-mass black hole punching through the accretion disk generated around a larger supermassive black hole. When the smaller black hole crosses through the disk, a flare emerges. Over long enough timescales, these black holes will inspiral and merge, generating a tremendous gravitational wave signal in the process. This bursting “double flare” system is a prominent characteristic of OJ 287.

Flaring bursts arise as the low-mass one punches through the larger’s accretion disk.

A close-up (left) and wider-field (right) view of the central nucleus of the nearby galaxy NGC 7727. Just 89 million light-years away, it houses the closest pair of binary supermassive black holes known, with a separation of 1,600 light-years. While friction with the environment can lead supermassive black holes to closely approach one another, the final stages of an inspiral and merger should come due to gravitational wave emission. Binary supermassive black holes are fairly common at the centers of galaxies, representing about 1-in-1000 galactic systems.

This “double quasar” isn’t unique, representing about 0.1% of all quasars.

When two supermassive black holes orbit one another, they not only perturb and accelerate the matter surrounding them, they leave definitive signatures in the emitted electromagnetic radiation that is complementary to the gravitational wave radiation, offering another avenue for direct detection and a way to independently confirm the black holes’ masses. Although this shows the radio data for binary black hole system 3C 344, the physics is very similar for the analogous OJ 287.

The space-based RadioAstron, combined with ground-based telescopes, enables VLBI: very long baseline interferometry.

In very-long baseline interferometry (VLBI), the radio signals are recorded at each of the individual telescopes before being shipped to a central location. Each data point that’s received is stamped with an extremely accurate, high-frequency atomic clock alongside the data in order to help scientists get the synchronization of the observations correct. The longer the separation between individual telescopes, the higher the maximum achievable resolution becomes.

This achieves our highest-ever resolution observations.

An X-ray and radio composite of OJ 287 during one of its flaring phases. The ‘orbital trail’ that you see in both views is a hint of the secondary black hole’s motion. This system is a binary supermassive system, where one component is approximately 18 billion solar masses and the other is 150 million solar masses. When they merge, they may emit as much energy, albeit in the form of gravitational waves, as was found in the most energetically-injected galaxy cluster.

A long ribbon-like radio jet was just discovered: enhancing our view of OJ 287.

This novel observation, taken with the space-based RadioAstron telescope in conjunction with a 27-element ground based array, provides ~15 micro-arc-second resolution of the distant black hole binary OJ 287. This ribbon-like radio jet reveals temperatures exceeding 10^13 K, with the ribbon’s shape indicating strong magnetic fields near the heavier of the two orbiting supermassive black holes.

In ~10,000 years, these black holes will merge.

This illustration maps out the various stages of a supermassive black hole merger, and the expected signals that scientists believe will emerge as the event unfolds. Once the two pre-merger black holes pass within the same event horizon, no further gravitational waves get emitted, save for the “ringdown” phase due to the changing shape of the post-merger event horizon.

The merger will release 3 × 10⁵⁴ J of gravitational wave energy: an inevitable, record-breaking event.

Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words.

Looking up at the night sky, it may seem our cosmic neighborhood is packed full of planets, stars and galaxies. But scientists have long suggested there may be far fewer galaxies in our cosmic surroundings than expected.

In fact, it appears we live in a giant cosmic void with roughly 20% lower than the average density of matter.

Not every physicist is convinced that this is the case. But our recent paper analyzing distorted sounds from the early universe, published in the Monthly Notices of the Royal Astronomical Society, strongly backs up the idea.

Cosmology is currently in a crisis known as the Hubble tension: the local universe appears to be expanding about 10% faster than expected. The predicted rate comes from extrapolating observations of the infant universe forward to the present day using the standard model of cosmology, known as Lambda-Cold Dark Matter (ΛCDM).

We can observe the early universe in great detail through the cosmic microwave background (CMB), relic radiation from the early universe, when it was 1,100 times smaller than it is today. Sound waves in the early universe ultimately created areas of low and high densities, or temperatures.

By studying CMB temperature fluctuations on different scales, we can essentially “listen” to the sound of the early universe, which is especially “noisy” at particular scales.

These fluctuations are now imprinted in the CMB, and dubbed “baryon acoustic oscillations” (BAOs). Since these became the seeds for galaxies and other structures, the patterns are also visible in the distribution of galaxies.

By measuring these patterns, we can learn how galaxies are clustered at different redshifts (distances). A particularly striking pattern, with lots of clustering, occurs at an angle called the “angular BAO scale.”

This measurement ultimately helps astronomers and cosmologists learn about the universe’s expansion history by providing something physicists call a “standard ruler.” This is essentially an astronomical object or a feature on the sky with a well-known size.

By measuring its angular size on the sky, cosmologists can therefore calculate its distance from Earth using trigonometry. One can also use the redshift to determine how fast the cosmos is expanding. The larger it appears on the sky at a certain redshift, the faster the universe is expanding.

My colleagues and I previously argued that the Hubble tension might be due to our location within a large void. That’s because the sparse amount of matter in the void would be gravitationally attracted to the denser matter outside it, continuously flowing out of the void.

In previous research, we showed that this flow would make it look like the local universe is expanding about 10% faster than expected. That would solve the Hubble tension.

But we wanted more evidence. And we know a local void would slightly distort the relation between the BAO angular scale and the redshift due to the faster-moving matter in the void and its gravitational effect on light from outside.

So in our new paper, Vasileios Kalaitzidis and I set out to test the predictions of the void model using BAO measurements collected over the last 20 years. We compared our results to models without a void under the same background expansion history.

In the void model, the BAO ruler should look larger on the sky at any given redshift. And this excess should become even larger at low redshift (close distance), in line with the Hubble tension.

The observations confirm this prediction. Our results suggest that a universe with a local void is about one hundred million times more likely than a cosmos without one, when using BAO measurements and assuming the universe expanded according to the standard model of cosmology informed by the CMB.

Our research shows that the ΛCDM model without any local void is in “3.8 sigma tension” with the BAO observations. This means the likelihood of a universe without a void fitting these data is equivalent to a fair coin landing heads 13 times in a row.

By contrast, the chance of the BAO data looking the way they do in void models is equivalent to a fair coin landing heads just twice in a row. In short, these models fit the data quite well.

In the future, it will be crucial to obtain more accurate BAO measurements at low redshift, where the BAO standard ruler looks larger on the sky – even more so if we are in a void.

The average expansion rate so far follows directly from the age of the universe, which we can estimate from the ages of old stars in the Milky Way. A local void would not affect the age of the universe, but some proposals do affect it.

These and other probes will shed more light on the Hubble crisis in cosmology.

Indranil Banik is postdoctoral research fellow in astrophysics, University of Portsmouth

This article is republished from The Conversation under a Creative Commons license. Read the original article.

This week, the Sturgeon Moon rises, giving moongazers across the world the chance to see a beautiful full Moon skimming the horizon.

The Sturgeon Moon is the August full Moon, the eighth full Moon of the year, and rises on 9 August at 21:13 BST.

What’s more, the Sturgeon Moon marks the beginning of a lunar meeting with the Solar System planets, the Moon tracking eastwards across the sky night after night and encountering Saturn, Jupiter, Venus and Mercury.

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Why Sturgeon Moon?

The term ‘Sturgeon Moon’ is one of many nicknames given to monthly full Moons, which reflect key changes or events in nature occurring during the month in question.

August’s full Moon is known as the Sturgeon Moon because this is the time of year when sturgeon fish were most plentiful and easiest to catch in the Great Lakes of North America.

The name reflects both the ecological cycle – as sturgeon would come into shallower waters in August – and the cultural importance of the fish as a food source in North America.

Other names for the August full Moon are Lynx Moon, Grain Moon and Corn Moon.

It’s important to remember, however, that these nicknames don’t indicate the full Moon will look different to any other full Moon of the year.

Nevertheless, full Moon names are a reminder of the changing of the seasons and the importance placed on the phases of the Moon by various cultures throughout history.

Observing the 2025 Sturgeon Moon

The Sturgeon Moon rises in the southeast around 9pm, although the exact timing will depend on your location.

It will then set in the southwest after sunrise the following morning, 10 August.

The Sturgeon Moon is located in the constellation Aquarius, and won’t rise very high above the horizon.

That means there’ll be a chance to observe a phenomenon known as the Moon illusion, whereby the Moon looks enormous when it’s close to the horizon.

This is an optical illusion: the Moon is in reality no bigger than when you observe it high up in the sky.

Take a look at the Sturgeon Moon. Does it look huge to you?

Full Moon is also a good time to observe features known as lunar rays.

For more info, read our guide on how to make the most of a full Moon.

The Moon meets the planets

After the Sturgeon Moon has risen and set, the coming evenings offer a good chance to see the now-waning Moon meet the planets of the Solar System in the night sky.

This is because the Moon tracks eastwards in the sky, night after night, so if there are multiple planets visible in the sky, the Moon often makes an apparent close approach to each one in turn.

Effectively, the Moon will join in the August 2025 planet parade.

It begins on 11–13 August when the Moon is close to Saturn, first to the right of the planet, and then to the left of the planet the following evening.

On the evenings of 15–17 August, the Moon tracks past the beautiful blue open star cluster known as the Pleiades in the constellation Taurus.

The planet Uranus is currently close to the Pleides, which means the Moon is also passing Uranus, too.

Get out your binoculars or telescope and see if you can observe the distant world. For more info, read our guide to observing Uranus in August 2025.

In the very early hours of 18 August, and the following morning of 19 August, if you can get a clear view of the eastern horizon before sunrise, you’ll see the Moon forming a line with Mercury, Venus and Jupiter, stretching upwards.

Mercury will be very close to the horizon, followed by Venus, then Jupiter and the Moon at the top.

On 20 August, the Moon will have tracked further east, disrupting this multi-planet and Moon alignment in the sky.

But instead, the Moon forms a beautiful triangle with Venus and Jupiter.

Then on 21 August, the Moon is just above Mercury in the very early hours before sunrise.

From this point onwards, Mercury is becoming much easier to see in the morning sky, having emerged from the glare of the rising Sun.

This makes the 21 August meeting between Mercury and the Moon a standout moment for observing Mercury.

From 22 August onwards, the Moon is approaching its ‘new Moon’ phases, meaning it’s beginning to be swallowed by the morning sunrise.

If you observe the Sturgeon Moon or the Moon’s meeting with the planets this month, share your observations and images with us by emailing contactus@skyatnightmagazine.com