Category: 7. Science

Oak gall wasps and their predators don’t have the panache of butterflies, but they’re attracting growing interest among both scientists and naturalists.

Only 1 to 8 millimeters long, these small insects create the tumor-like plant growths known as “galls.” Small as a pinhead or large as an apple, galls can take striking shapes, with some resembling sea urchins or saucers, explained Binghamton University Associate Professor of Biological Sciences Kirsten Prior, who also co-leads Binghamton’s Natural Global Environmental Change Center.

And if these wasps are a mascot for anything, it’s biodiversity. North America has around 90 different species of oak trees, and around 800 species of oak gall wasps that live upon them. Parasitic wasps lay their eggs in the galls and go on to devour the entire oak gall wasp.

But how many species of parasitoid wasps are out there? That’s a question that scientists — both academic researchers traveling the globe and everyday citizens in their own backyard — are working to answer.

A recent article in the Journal of Hymenoptera Research, “Discovery of two Palearctic Bootanomyia Girault (Hymenoptera, Megastigmidae) parasitic wasp species introduced to North America,” gives insight into a previously unknown level of species diversity. In addition to Prior, co-authors include current graduate student Kathy Fridrich and former graduate student Dylan G. Jones, as well as Guerin Brown, Corey Lewis, Christian Weinrich, MaKella Steffensen and Andrew Forbes of the University of Iowa, and Elijah Goodwin of the Stone Barns Center for Food and Agriculture in Tarrytown, N.Y.

This discovery is part of a larger research effort. In 2024, the National Science Foundation awarded a $305,209 grant to Binghamton University for research into the diversity of oak gall wasps and parasitoids throughout North America. The project is a collaboration between Prior, Forbes at the University of Iowa, Glen Hood at Wayne State University and Adam Kranz, one of the creators behind the website Gallformers.org, which helps people learn about and identify galls on North American plants.

The NSF grant investigates a core question: How do gall-forming insects escape diverse and evolving clades of parasitic wasps — and how do parasites catch up? To answer that question, researchers are collecting oak gall wasps around North America and using genetic sequencing to determine which parasitic wasps emerge from the galls. Among them are Fridrich and fellow Binghamton graduate student Zachary Prete, who spent the summer on a gall- and parasitoid-collection trip from New York to Florida.

“We are interested in how oak gall characteristics act as defenses against parasites and affect the evolutionary trajectories of both oak gall wasps and the parasites they host. The scale of this study will make it the most extensive cophylogenetic study of its kind,” Prior said. “Only when we have a large, concerted effort to search for biodiversity can we uncover surprises — like new or introduced species.”

Discovering unknown species

Over the past several years, researchers with Prior’s lab traveled the West Coast from California to British Columbia, collecting approximately 25 oak gall wasp species and rearing tens of thousands of parasitic wasps, which were ultimately identified as more than 100 different species.

Some of the parasitoids, reared from oak gall wasp species from several locations, turned out to be the European species Bootanomyia dorsalis in the wasp family Megastigmidae. Researchers at the University of Iowa identified a similar wasp from collections they made in New York state.

“Finding this putative European species on the two coasts of North America inspired our group to confirm this parasitic species’ identity and whether it was, in fact, an introduced parasite from Europe,” Prior explained.

Parasitic wasps are small and challenging to identify based on features alone. Because of this, researchers use genetic tools to confirm a species’ identity, sequencing “the universal barcoding gene,” Cytochrome Oxidase Subunit I (mtCOI), and comparing their results to reference libraries. What they discovered is that the European species B. dorsalis came in two separate varieties, or clades: the New York samples were related to species in Portugal, Iran and Italy, while the Pacific coast wasps were related to those from Spain, Hungary and Iran.

“The sequences from two clades were different enough from each other that they could be considered different species. This suggests that B. dorsalis was introduced at least twice, and that the New York and West Coast introductions were separate,” Prior said.

And while they were found in at least four different oak gall wasp species from Oregon to British Columbia, all the West Coast B. dorsalis wasps were genetically identical, which means that their introduction was small and localized. The East Coast wasps had slightly more genetic diversity, which could indicate that there was less of a population bottleneck, or that the species was introduced more than once.

How did the European species get here? One possibility is that non-native oak species were intentionally introduced to North America. English oak, or Quercus robur, was widely planted for wood since the 17th century, and is found in British Columbia as well as several northeastern states and provinces. Turkey oak, Q. cerris, is an ornamental tree now found along the East Coast — including a spot near where B. dorsalis was discovered in New York.

There are other possibilities. Adult parasitic wasps can live for 27 days, so they could have hitchhiked on a plane, Prior said.

Researchers don’t yet know if these introduced species pose a hazard to native North American species. Other introduced parasite species are known to impact populations of native insects, she acknowledged.

“We did find that they can parasitize multiple oak gall wasp species and that they can spread, given that we know that the population in the west likely spread across regions and host species from a localized small introduction,” Prior said. “They could be affecting populations of native oak gall wasp species or other native parasites of oak gall wasps.”

Naturalists and citizen scientists play an important role in biodiversity research, such as the project that led to the discovery of the two B. dorsalis clades. Gall Week, a project hosted on the platform iNaturalist, encourages citizen scientists to collect galls during two seasons, and specimens from the NSF-funded study will be posted on the naturalist site Gallformers.org. Binghamton University ecology classes have participated in Gall Week, and also logged galls during University’s annual Ecoblitz biodiversity event.

Biodiversity is a key component to healthy and functioning ecosystems — and one that is increasingly under threat due to global change.

“Parasitic wasps are likely the most diverse group of animals on the planet and are extremely important in ecological systems, acting as biological control agents to keep insects in check, including those that are crop or forest pests,” Prior explained.

Reference: Brown GE, Lewis CJ, Fridrich K, et al. Discovery of two Palearctic Bootanomyia Girault (Hymenoptera, Megastigmidae) parasitic wasp species introduced to North America. J Hymenopt Res. 2025. doi:10.3897/jhr.98.152867

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Astronomers using the Inouye Solar Telescope have captured the sharpest solar flare images ever taken, revealing delicate, threadlike plasma loops as narrow as 21 kilometers.

These ultra-fine structures, caught during an explosive X-class flare, provide the clearest evidence yet of the Sun’s hidden architecture and may represent the fundamental building blocks of flare activity.

Record-Breaking Solar Flare Imaging

The most detailed images ever taken of a solar flare at the H-alpha wavelength (656.28 nm) are giving scientists a new look at the Sun’s magnetic structures and may improve our ability to predict space weather. Using the U.S. National Science Foundation (NSF) Daniel K. Inouye Solar Telescope, operated by the NSF’s National Solar Observatory (NSO), researchers recorded remarkably fine strands of dark coronal loops during the fading stage of an X1.3-class flare on August 8, 2024, at 20:12 UT. These loops measured an average width of 48.2 km, with some appearing as slim as 21 km. They are the narrowest coronal loops ever seen, representing a major advance in pinpointing the fundamental scale of these features and expanding the boundaries of solar flare modeling.

Coronal loops are glowing arcs of plasma shaped by the Sun’s magnetic field lines. They often appear before solar flares, which occur when certain magnetic field lines twist and break, releasing bursts of energy. These eruptions drive solar storms that can disrupt Earth’s satellites, power grids, and communication systems. By observing at the H-alpha wavelength (656.28 nm), the Inouye telescope can highlight specific features of the Sun that remain invisible in other kinds of observations.

A high-cadence, high-resolution movie of the flare, captured by the Inouye Solar Telescope, has been sped up 100 times. Both bright ribbons and dark overlying coronal loops are visible. The image is about 4 Earth diameters on each side. Credit: NSF/NSO/AURA

First X-Class Flare Observed by Inouye

“This is the first time the Inouye Solar Telescope has ever observed an X-class flare,”explains Cole Tamburri, the study’s lead author. Tamburri is supported by the Inouye Solar Telescope Ambassador Program while pursuing his Ph.D. at the University of Colorado Boulder (CU). Funded by the NSF, the program is designed to train Ph.D. students as part of a connected network of early-career scientists at U.S. universities who will share expertise in Inouye data analysis across the solar research community. “These flares are among the most energetic events our star produces, and we were fortunate to catch this one under perfect observing conditions.”

The research team, which included scientists from the NSO, the Laboratory for Atmospheric and Space Physics (LASP), the Cooperative Institute for Research in Environmental Sciences (CIRES), and CU, concentrated on the delicate magnetic loops spread above the flare’s bright ribbons. In total, hundreds of these features were visible, averaging around 48 km in width, with some loops right at the telescope’s resolution limit. “Before Inouye, we could only imagine what this scale looked like,” Tamburri explains. “Now we can see it directly. These are the smallest coronal loops ever imaged on the Sun.”

Pushing Resolution Limits in Solar Science

The Inouye’s Visible Broadband Imager (VBI) instrument, tuned to the H-alpha filter, can resolve features down to ~24 km. That is over two and a half times sharper than the next-best solar telescope, and it is that leap in resolution that made this discovery possible. “Knowing a telescope can theoretically do something is one thing,” Maria Kazachenko, a co-author in the study and NSO scientist, notes. “Actually watching it perform at that limit is exhilarating.”

While the original research plan involved studying chromospheric spectral line dynamics with the Inouye’s Visible Spectropolarimeter (ViSP) instrument, the VBI data revealed something unexpected treasures—ultra-fine coronal structures that can directly inform flare models built with complex radiative-hydrodynamic codes. “We went in looking for one thing and stumbled across something even more intriguing,” Kazachenko admits.

Confirming Theories on Coronal Loop Scales

Theories have long suggested coronal loops could be anywhere from 10 to 100 km in width, but confirming this range observationally has been impossible—until now. “We’re finally peering into the spatial scales we’ve been speculating about for years,” says Tamburri. “This opens the door to studying not just their size, but their shapes, their evolution, and even the scales where magnetic reconnection—the engine behind flares—occurs.”

Perhaps most tantalizing is the idea that these loops might be elementary structures—the fundamental building blocks of flare architecture. “If that’s the case, we’re not just resolving bundles of loops; we’re resolving individual loops for the first time,” Tamburri adds. “It’s like going from seeing a forest to suddenly seeing every single tree.”

Breathtaking Imagery and Landmark Moment

The imagery itself is breathtaking: dark, threadlike loops arching in a glowing arcade, bright flare ribbons etched in almost impossibly sharp relief—a compact triangular one near the center, and a sweeping arc-shaped one across the top. Even a casual viewer, Tamburri suggests, would immediately recognize the complexity. “It’s a landmark moment in solar science,” he concludes. “We’re finally seeing the Sun at the scales it works on.” Something made only possible by the NSF Daniel K. Inouye Solar Telescope’s unprecedented capabilities.

Reference: “Unveiling Unprecedented Fine Structure in Coronal Flare Loops with the DKIST” by Cole A. Tamburri, Maria D. Kazachenko, Gianna Cauzzi, Adam F. Kowalski, Ryan French, Rahul Yadav, Caroline L. Evans, Yuta Notsu, Marcel F. Corchado-Albelo, Kevin P. Reardon and Alexandra Tritschler, 25 August 2025, The Astrophysical Journal Letters.
DOI: 10.3847/2041-8213/adf95e

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Clues about how worlds like Earth may have formed have been found buried at the heart of a spectacular ‘cosmic butterfly’.

With the help of the James Webb Space Telescope, researchers say they have made a big leap forward in our understanding of how the raw material of rocky planets comes together.

This cosmic dust – tiny particles of minerals and organic material which include ingredients linked to the origins of life – was studied at the core of the Butterfly Nebula, NGC 6302, which is located about 3,400 light-years away in the constellation Scorpius.

From the dense, dusty torus that surrounds the star hidden at the centre of the nebula to its outflowing jets, the Webb observations reveal many new discoveries that paint a never-before-seen portrait of a dynamic and structured planetary nebula.

They have been published today in Monthly Notices of the Royal Astronomical Society .

Most cosmic dust has an amorphous, or randomly oriented-atomic structure, like soot. But some of it forms beautiful, crystalline shapes, more like tiny gemstones.

“For years, scientists have debated how cosmic dust forms in space. But now, with the help of the powerful James Webb Space Telescope, we may finally have a clearer picture,” said lead researcher Dr Mikako Matsuura, of Cardiff University.

“We were able to see both cool gemstones formed in calm, long-lasting zones and fiery grime created in violent, fast-moving parts of space, all within a single object.

“This discovery is a big step forward in understanding how the basic materials of planets, come together.”

The Butterfly Nebula’s central star is one of the hottest known central stars in a planetary nebula in our galaxy, with a temperature of 220,000 Kelvin.

This blazing stellar engine is responsible for the nebula’s gorgeous glow, but its full power may be channelled by the dense band of dusty gas that surrounds it: the torus.

The new Webb data show that the torus is composed of crystalline silicates like quartz as well as irregularly shaped dust grains. The dust grains have sizes on the order of a millionth of a metre — large, as far as cosmic dust is considered — indicating that they have been growing for a long time.

Outside the torus, the emission from different atoms and molecules takes on a multilayered structure. The ions that require the largest amount of energy to form are concentrated close to the centre, while those that require less energy are found farther from the central star.

Iron and nickel are particularly interesting, tracing a pair of jets that blast outward from the star in opposite directions.

Intriguingly, the team also spotted light emitted by carbon-based molecules known as polycyclic aromatic hydrocarbons, or PAHs. They form flat, ring-like structures, much like the honeycomb shapes found in beehives.

On Earth, we often find PAHs in smoke from campfires, car exhaust, or burnt toast.

Given the location of the PAHs, the research team suspects that these molecules form when a ‘bubble’ of wind from the central star bursts into the gas that surrounds it.

This may be the first-ever evidence of PAHs forming in a oxygen-rich planetary nebula, providing an important glimpse into the details of how these molecules form.

NGC 6302 is one of the best-studied planetary nebulae in our galaxy and was previously imaged by the Hubble Space Telescope .

Planetary nebulae are among the most beautiful and most elusive creatures in the cosmic zoo. These nebulae form when stars with masses between about 0.8 and 8 times the mass of the Sun shed most of their mass at the end of their lives. The planetary nebula phase is fleeting, lasting only about 20,000 years.

Contrary to the name, planetary nebulae have nothing to do with planets: the naming confusion began several hundred years ago, when astronomers reported that these nebulae appeared round, like planets.

The name stuck, even though many planetary nebulae aren’t round at all — and the Butterfly Nebula is a prime example of the fantastic shapes that these nebulae can take.

The Butterfly Nebula is a bipolar nebula, meaning that it has two lobes that spread in opposite directions, forming the ‘wings’ of the butterfly. A dark band of dusty gas poses as the butterfly’s ‘body’.

This band is actually a doughnut-shaped torus that’s being viewed from the side, hiding the nebula’s central star — the ancient core of a Sun-like star that energises the nebula and causes it to glow. The dusty doughnut may be responsible for the nebula’s insectoid shape by preventing gas from flowing outward from the star equally in all directions.

The new Webb image zooms in on the centre of the Butterfly Nebula and its dusty torus, providing an unprecedented view of its complex structure. The image uses data from Webb’s Mid-InfraRed Instrument ( MIRI ) working in integral field unit mode.

This mode combines a camera and a spectrograph to take images at many different wavelengths simultaneously, revealing how an object’s appearance changes with wavelength. The research team supplemented the Webb observations with data from the Atacama Large Millimetre/submillimetre Array, a powerful network of radio dishes.

Researchers analysing these Webb data identified nearly 200 spectral lines, each of which holds information about the atoms and molecules in the nebula. These lines reveal nested and interconnected structures traced by different chemical species.

The research team were able to pinpoint the location of the Butterfly Nebula’s central star, which heats a previously undetected dust cloud around it, making the latter shine brightly at the mid-infrared wavelengths that MIRI is sensitive to.

The location of the nebula’s central star has remained elusive until now, because this enshrouding dust renders it invisible at optical wavelengths. Previous searches for the star lacked the combination of infrared sensitivity and resolution necessary to spot its obscuring warm dust cloud.

A bee-like robot currently under development at the Massachusetts Institute of Technology (MIT) is part of a new generation of bots inspired by creepy crawlies.

The machine, which weighs less than a paperclip, can flap its wings up to 400 times a second and has achieved a maximum speed of two meters (6.5 feet) per second. It can also flip and hover.

“We’re just trying to mimic these amazing maneuvers that bumblebees can achieve,” says Yi-Hsuan “Nemo” Hsiao, a fourth-year PhD student who is working on the robots.

Researchers hope that it could someday help with tasks like artificial pollination, maybe even on other planets.

“If you’re going to grow something on Mars, you probably don’t want to bring a lot of natural insects to do the pollination,” says Hsiao. “That’s where our robot could potentially come into play,” he adds.

Kevin Chen, an associate professor at MIT and the principal investigator at its Soft and Micro Robotics Lab adds that the team doesn’t want to replace bees, but put the robots to work in scenarios where the insects can’t.

They could be used in warehouse farms with rows of crops stacked high and ultraviolet lighting, he says: “It’s very difficult for bees to survive in that environment.”

Across the world, technologists are taking lessons from nature to create robots that might perform better at complex tasks or in difficult environments than traditional technology.

At Yale University, researchers developed a gecko-inspired robot that can amputate its own limbs – a capability that could be helpful in search and rescue missions in dangerous rubble, according to its creators.

And researchers at South Korea’s Chung-Ang University recently unveiled a soft robot that can bend and crawl like a caterpillar.

“Millions of years of evolution has helped to give (insects and animals) the best solution, especially for any type of locomotion,” says Hsiao, who writes the algorithms that tells the bee robots how to move.

The robot bee flies using soft artificial muscles that elongate and contract to flap the wing, developed by PhD candidate Suhan Kim. The robot’s laser-cut wings, and its tiny internal mechanisms, similar in size to watch components, are also made in-house.

The team is also working on a grasshopper-like robot. The machine, smaller than a human thumb, can hop 20 centimeters (almost 8 inches) into the air and take on terrains ranging from grass to ice to a leaf. Hsiao says that the jumping robot is more energy efficient than a flying robot.

The small size of the bee and grasshopper-like robots means they could be useful for search and rescue missions or exploring places like the inside of a pipeline or a turbine engine.

Hsiao says the next step in taking the technology into the real world is to add sensors that can feed information to the robots, and batteries to power them. The machines currently rely on a wire to power them. “It’s very difficult to put a small energy source onboard tiny robots,” adds Chen.

The ability to deploy a fully autonomous robot in the field could be 20 to 30 years away, he estimates.

But studying insects’ natural abilities will give his team a jumpstart. “They have evolved for millions of years” says Chen. “There’s a lot to be learned from insect motion, behavior and structure.”

DNA bends, loops, and crosses itself in cramped cells, and those ‘knots’ can help or hinder life. Scientists have long taught the neat ladder-like twist, but spent years wrestling with the messier truth.

Researchers have now developed a rapid method to visualize DNA crossings and determine, at the level of single molecules, which strand passes over or under the other.

The method pairs high-resolution imaging with smart software and quickly delivers answers that used to take a lot of time. The research was led by Alice Pyne, a professor of biophysics at the University of Sheffield.

Mapping DNA’s hidden knots

The group imaged DNA using atomic force microscopy (AFM) and then traced each molecule’s path with a deep-learning pipeline that identifies every crossing and labels it as over or under.

The team demonstrated that they can recover the topology, the length, and the local shape of single DNA circles and their tangles with sub-molecular detail.

Unlike light-based microscopes, atomic force microscopy feels the surface with a nanoscale probe, which makes it well suited to single molecule work in fluid.

The role of atomic force microscopy

A previous study showed that atomic force microscopy can map DNA, without staining, under near-cellular conditions.

The Sheffield pipeline advances this by measuring the height profile at each strand crossing and applying a full-width-at-half-maximum comparison to identify which DNA strand passes over. This method increases accuracy, especially when crossings occur in close proximity.

The software then outputs a topological class for the whole molecule, so researchers do not have to infer knot types by gel position or by eye.

DNA knots and disease

Cells rely on DNA topology to manage access to genes and to keep the genome intact. When the balance tips, damage builds up and repair systems struggle.

A comprehensive review explains how each human topoisomerase family member cuts and rejoins DNA to manage supercoiling and catenation. It also shows how these enzymes serve as important targets for antibiotics and anti-cancer drugs.

Those links are not abstract. Mismanaged crossings and twists during replication or transcription trigger breaks, stalled forks, altered gene expression, and increased disease risk.

A method that cleanly reads which strand sits on top at each crossing can show when and where the cell’s topological control slips, and it can reveal how drug candidates change those patterns.

To show the software works beyond simple plasmids, the authors tested it on replication intermediates formed in Xenopus egg extracts. This well-established system mimics DNA synthesis outside a living cell.

Protocols for these extracts show they contain all the factors needed to license and copy DNA, which lets scientists pause forks and capture real intermediates.

They also created specific DNA knots and links using E. coli proteins and then tested whether the system could correctly identify them.

The team demonstrated that the method could measure the size of simple DNA circles with about one percent accuracy. It also distinguished between two similar five-crossing knot types by tracking how the strands crossed over or under each other.

“We have done that by developing advanced new image-analysis tools that can do in a matter of seconds that before may have taken hours,” said Pyne.

Telling strands apart

The hardest part of visualizing a tangle is not seeing that two segments cross – it is telling which one is on top. The authors solved this problem by using the small but measurable height difference at each crossing.

The researchers then trained a model to follow the DNA paths without losing track at tight junctions.

“DNA is a really long molecule,” said study co-author Dr. Sean Colloms from the School of Molecular Bioscience at the University of Glasgow. “Just like any long piece of string, the DNA in our cells gets tangled and knotted.”

“At each DNA crossing, we can see which piece of DNA goes over which and this even allows us to tell the difference between one knot and its mirror image, which is important in our studies.”

DNA knots guide new drugs

The ability to classify tangles on single molecules gives drug hunters a readout for compounds that alter replication, transcription, or decatenation.

It can also guide design in DNA nanotechnology, where loops and crossings are part of the scaffold rather than a nuisance.

Previous studies have already used atomic force microscopy to see how supercoiling changes groove width and local recognition. This work suggests that shape cues may help guide protein binding.

“By developing advanced models, we can generate thousands of molecular structures to train future AI frameworks, bringing us closer to visualizing and understanding topology of complex DNA assemblies,” said Dušan Račko of the Polymer Institute of the Slovak Academy of Sciences (SAS).

DNA mapping is not easy

Every method has trade-offs. Atomic force microscopy requires attaching DNA to a surface and pushing gently with a tip, so adsorption and imaging forces can change conformation if conditions are not tuned well.

A 2021 AFM review shows how cations, polymers, and scan settings shape mica results, stressing consistency.

Even so, the Sheffield pipeline reduces observer bias and scales analysis so that tricky cases can be flagged by their confidence scores instead of quietly misread.

It also makes replication biology more concrete by turning fork junctions, gaps, and reversed forks into numbers rather than sketches. That shift from impression to measurement is what lets the field ask sharper questions.

There is room to grow. The same tracing approach should extend to RNA, to protein-nucleic acid complexes, and to engineered lattices.

Adding live imaging and selective chemistries could link topological snapshots to time and to specific proteins, which could refine readouts for topoisomerase drugs and beyond.

The study is published in the journal Nature Communications.

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Six planets will be visible in the morning sky before sunrise on Thursday, Aug. 28, but for probably the last time until 2028. Venus shines brightest in the east, flanked by Jupiter, with and Saturn in the south. Mercury clings low to the horizon, offering a final glimpse before it disappears into sunlight next week. Uranus and Neptune are also part of the line-up, though you’ll need binoculars or a telescope to complete the set.

Key Facts

Saturn And The ‘great Square Of Pegasus’

Look to the southwest before sunrise for Saturn, and alongside it, you’ll also notice a vast, simple shape in the sky. Four bright stars forming a neat quadrilateral, the Great Square of Pegasus anchors the constellation Pegasus, the mythical winged horse. Its corner stars — Scheat, Alpheratz, Markab and Algenib — create one of the most recognisable shapes in the night sky in late summer and early fall, which is still visible before sunrise.

What’s Next In The Night Sky

September’s night sky is far from quiet after August’s planet parade. With Mercury hidden in the sun’s glare, Saturn, Jupiter and Venus take center stage to create — with Neptune and Uranus — a five-planet display. On Sept. 7, there’s a total lunar eclipse, visible from Asia, Africa and western Australia, when the full moon will turn a coppery red as it travels through Earth’s shadow. To enjoy it, find a dark spot and simply look up — no telescope required. On Sept. 19, a waning crescent moon will position itself very near Venus and Regulus in Leo, creating a striking sight. Then comes Sept. 21, when Saturn reaches opposition on the same day as a partial solar eclipse across the Pacific.

Further Reading

Forbes‘Planet Parade’ Myths Debunked And How To Truly See It — By A StargazerBy Jamie CarterForbesNASA Urges Public To Leave The City As Milky Way Appears — 15 Places To GoBy Jamie CarterForbes9 Places To Experience The Next Total Solar Eclipse A Year From TodayBy Jamie Carter

It’s amazing how far we’ve come, scientifically, in the span of only ten years. Back in 2015, humanity didn’t know whether a core prediction of Einstein’s General Relativity — the existence of energy-carrying gravitational waves — was true or not. We had theoretical predictions that these waves should be generated whenever a massive object moved and accelerated through a changing gravitational field, and we had observed orbital decay of binary systems (like binary pulsars) that were consistent with those predictions, but the ripples in spacetime themselves, or gravitational waves, had never been directly detected. For 100 years, this great prediction of physics remained unconfirmed.

Then, on September 14, 2015, all of that changed. The twin LIGO (Laser Interferometer Gravitational-wave Observatory) detectors both saw small, periodic changes in the length of their four-kilometer-long laser arms, which heralded the arrival of gravitational waves from two black holes that had recently inspiraled and merged from across the Universe. With that one event, the era of gravitational wave astronomy was born: a wholly new type of astronomy that didn’t use telescopes, but rather was sensitive to the ripples in spacetime generated by these energetic mergers of compact objects.

Now in 2025, after years of observing runs punctuated by a steady series upgrades between them, LIGO — in the midst of its fourth observing run — has just more than tripled the number of known black hole mergers, going from around 90 at the end of the third run to around 300 today. Here’s how far we’ve come in the last decade, and how, if we don’t take radical action, this era might come to a sudden, unceremonious end.

The story of gravitational waves begins with Einstein’s General Relativity. If all you have is one static, unchanging mass in your spacetime, it’s going to be stable and unchanging: the mass will remain constant and so will the spacetime surrounding it. But if you have a second mass in the vicinity of the first, they’ll both accelerate due to the influence of the other, moving around through spacetime, all while the spacetime’s curvature itself changes in response. This has a profound effect in analogy with electromagnetism.

• In classical electromagnetism (obeying Maxwell’s equations), an electrically charged particle moving or accelerating through a changing electromagnetic field will emit electromagnetic radiation in the form of light, or photons.
• Similarly, in classical gravity (obeying Einstein’s equations), a massive particle (with a gravitational charge) moving or accelerating through a changing gravitational field (a region of spacetime where the curvature changes) will emit gravitational radiation in the form of gravitational waves.

These waves must carry energy and must move at the speed of light. And, according to the theory of General Relativity, as those gravitational waves propagate away from the massive sources that generated them by their motion through spacetime, they cause the space that they propagate through to alternately expand (grow) and contract (shrink), in phase, in mutually perpendicular directions.

When a gravitational wave passes through a location in space, it causes an expansion and a compression at alternate times in alternate directions, causing laser arm-lengths to change in mutually perpendicular orientations. Exploiting this physical change is how we developed successful gravitational wave detectors such as LIGO and Virgo. However, unlike this illustration, the gravitational waves do not simply propagate in a “tube,” but rather spread out through all of three-dimensional space.

For a long time, astronomers hoped to uncover evidence for the existence of these gravitational waves. They got a whiff of hope back in 1974, when astronomers Russell Hulse and Joseph Taylor discovered a highly unusual star system: a system containing two neutron stars, where one of those neutron stars was emitting regular pulses every 59 milliseconds. Known as a binary pulsar, the arrival time of the pulses exhibited regular variations every 7 hours and 45 minutes, which led to the detection of the binary companion. Each neutron star is massive — containing more mass than the entire Sun — but extremely compact, at around ~20 kilometers in size. They orbit one another in a very elliptical fashion, coming as close as 746,600 kilometers (about the radius of the Sun) but reaching maximum separations of 3,153,600 km (about four solar radii).

Here’s the kicker, though: these orbits aren’t constant over time, but very slowly decay. As these large masses move through space at close separations to one another, the accelerated motion through spacetime whose curvature is changing results in the steady emission of gravitational waves, where that emitted energy comes at the expense of the orbital energy of the two bodies. Each year, the orbits shrink by about 3.5 meters, and the orbital period shortens by 76.5 microseconds. Although the gravitational waves from these two neutron stars are too weak to directly detect, the observed change in the pulse periods over time provided indirect evidence that these gravitational waves must exist.

As two neutron stars orbit one another, the motion of one mass through the curved spacetime generated by the other mass results in the emission of gravitational waves, which carry energy away and cause the orbits to decay. The first binary neutron star system, where at least one neutron star is a pulsar, was discovered in 1974. Even as early as 1982, as the inset diagram shows, the orbit could be observed decaying, in agreement with General Relativity’s predictions.

However, there ought to be sources that were so energetic out there in the Universe that, in principle, an appropriately designed gravitational wave detection apparatus could be sensitive to those ripples in spacetime. In particular, when a compact, massive source and another compact, massive source achieve very tight orbits with one another, they’ll reach such small separations that either:

• their surfaces will touch and they’ll interact,
• or, if one or both of the objects is a black hole, one object will encounter the event horizon of the other and merge.

These are the scenarios that emit gravitational waves of the maximum amount of energy, with the frequency of the emitted gravitational waves corresponding to the masses of the objects and their minimum separation distances before interaction and/or merger.

In order to detect these gravitational waves, you have to understand that the waves will propagate through space, causing expansion-and-contraction oscillations to happen when the waves pass through. To catch them passing through, scientists concocted the brilliant design of gravitational wave detectors: sending a split laser pulse down two mutually perpendicular vacuum tubes, reflecting them back-and-forth many times, and then bringing them back together to construct an interference pattern. When there’s no gravitational wave, the pattern remains constant, but when a gravitational wave passes through the apparatus, the path lengths change, altering the arrival time of the pulses and leading to detectable changes in the interference pattern that results.

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.

That’s the basics of how gravitational wave detectors works. LIGO — with twin detectors located in Livingston, Louisiana and Hanford, Washington — used arms that were approximately 4 kilometers each in length and leveraged about 1000 laser reflections in each one before those two laser beams were brought back together. Theorists calculated thousands of gravitational wave templates based on the types of:

• black hole-black hole mergers,
• black hole-neutron star mergers,
• and neutron star-neutron star mergers

that they expected to occur across the Universe, modeling a variety of spins, masses, and orientations to them.

Advanced LIGO, which grew out of the proof-of-concept prototype that was the original LIGO, turned on in early September of 2015. While still undergoing calibration, this first gravitational wave unexpectedly arrived, but the detectors were performing so well, and the arriving signal was so strong, that both detectors immediately registered the signal. Humanity had detected our first ever gravitational wave event: a merger of two black holes, one of 36 solar masses and another of 29 solar masses, that resulted in the production of a 62 solar mass black hole. With just a little math, you’ll notice that 3 solar masses were “lost,” but they weren’t actually lost; they were merely converted to energy via E = mc², where that energy was in the form of gravitational waves.

GW150914 was the first ever direct detection and proof of the existence of gravitational waves. The waveform, detected by both LIGO observatories, Hanford and Livingston, matched the predictions of general relativity for a gravitational wave emanating from the inward spiral and merger of a pair of black holes of around 36 and 29 solar masses and the subsequent “ringdown” of the single resulting black hole.

By transferring a tiny amount of that gravitational wave energy into the LIGO detectors, we were able to detect that signal from across the Universe. Subsequently, more data was taken, and a few more events were seen. After detecting those events, both detectors were shut down and received upgrades, with some of the systems that received upgrades being:

• the vacuum systems within the laser cavities,
• the temperatures and reflectivities of the mirrors,
• the squeezing of the quantum states that created the laser beams,
• and the sources of error and noise that limited the detector’s sensitivity were lowered as well,

making LIGO more sensitive to gravitational waves generated at greater distances. With each new factor of two in sensitivity that LIGO (or any gravitational wave detector) achieved, it became sensitive to eight times as much volume as previously, since our three-dimensional space means that twice the sensitivity enables detections at double the distance in all three dimensions. Every new upgrade meant increased sensitivity, which meant a greater volume of the Universe to probe for these gravitational wave events. More volume means more events, and that means the rate of detections only increased as these upgrades continued.

Within LIGO’s vacuum chamber, laser light is now created in not only a squeezed fashion, but where quantum squeezing occurs in a frequency-dependent fashion. The squeezer is operational in this photo, as green laser light is being pumped through it.

LIGO was then joined by the Virgo detector, a slightly smaller gravitational wave detector in Europe, which enabled astronomers to pinpoint (or triangulate, because we now had three detectors total) the location from which gravitational wave events emerged. By the end of the second observing run, we had reached double digits of gravitational wave detections, with the first neutron star-neutron star merger joining all of the other black hole-black hole merger we’d seen. When the second observing run came to a close, further upgrades to LIGO and Virgo were enacted, and then later on, the KAGRA detector joined the gravitational wave party as well.

By the end of the third observing run in 2020, a total of around 90 gravitational wave events had been seen. By this point, all three types of events, including neutron star-neutron star mergers and neutron star-black hole mergers, were all seen. We learned that neutron star-neutron star mergers didn’t always produce kilonovae, but sometimes, dependent on properties such as the initial masses of the neutron stars, would lead to a black hole directly upon contact. Some of the black hole mergers seen fell into the “mass gap” window of between 5 and 10 solar masses: a region where some had theorized black holes couldn’t have existed. In only a few years, we knew of more stellar mass black holes from gravitational wave events than from all other methods of detection combined.

The most up-to-date plot including LIGO’s Observing Run 3 data, as of November 2021, of all the black holes and neutron stars observed both electromagnetically and through gravitational waves. While these include objects ranging from a little over 1 solar mass, for the lightest neutron stars, up to objects a little over 100 solar masses, for post-merger black holes, gravitational wave astronomy is presently only sensitive to a very narrow set of objects. The closest black holes had all been found as X-ray binaries, until the November 2022 discovery of Gaia BH1. The mass “border” between neutron stars and black holes is still being determined.

In fact, black hole-black hole mergers were by far the most ubiquitous type of event that appeared in gravitational waves, and the twin LIGO detectors remained the strongest sources of signal for all such observed events. In a new pair of papers whose preprints were released on August 25, 2025 — just three weeks prior to the 10-year anniversary of the arrival of the first directly detected gravitational wave — the LIGO, Virgo, and KAGRA collaborations combined to release a new catalogue of their highest-significance detection events of all-time. Although the ongoing Observing Run 4 has detected more than 200 sources on its own, the new catalogue stops with the events ending in January of 2024, bringing the total up to 218 released and vetted events, more than doubling the total (of 90) from the end of Observing Run 3.

The graphs you see (sometimes called “Eagle plots” because of their shape), above and below, shows the known black holes and neutron stars below 300 solar masses. The top graph shows the ones known at the end of Observing Run 3 alone; the lower graph shows the ones as of the end of the first part of Observing Run 4. The blue points indicate black holes detected from gravitational waves, the orange points indicate neutron stars observed in gravitational waves. The red and yellow points, for comparison, show black holes and neutron stars detected through electromagnetic (light-driven) signals, showcasing just how remarkable the science of gravitational wave detection has been for learning about the populations of black holes below ~300 solar masses.

This “Eagle” plot shows the black holes and neutron stars, as a function of mass, that were detected by either gravitational wave events (blue and orange) or with electromagnetic signatures (red and yellow). With the advent of the first part of LIGO’s Observing Run 4 data, we now have 218 robust gravitational wave events, with approximately 100 more in the pipeline.

As you can see even from just a visual inspection, there is no “mass gap” where objects are completely absent. However, visual inspections are insufficient tools for determining if there’s a population deficit or excess at any given mass or across any particular mass range; if we want to determine what’s present, what’s anomalous, and what appears to be missing, we have to perform the appropriate quantitative analysis. Fortunately, that’s what the second of the two released preprints, both of which are to be published in a special issue of Astrophysical Journal Letters, is all about.

Indeed, there isn’t a mass “gap” between around 5 and 10 solar masses, but there is a substantial mass deficit; there are more objects at lower masses and at 10 solar masses and above than there are masses in the in-between range. There’s are two, maybe three spikes in the mass distribution of black holes, with a peak at 10 solar masses and another peak at 35 solar masses, with a possible (but less significant) third feature at around 20 solar masses. Above 35 solar masses, the abundance of black holes drops off somewhat more steeply than the simple power-law curve that describes black holes at lower masses, suggesting some suppression of those higher-mass black holes. (Although the ones that do exist produce the largest-amplitude gravitational wave signals, making them relatively easy to spot.)

Below, a graph from the paper highlights some of these features.

This graph shows the differential merger rate (y-axis) as a function of the mass of the heavier black hole (x-axis) involved in the merger of two black holes as seen in gravitational wave events. The orange and blue shaded areas indicate the confidence intervals of two different models, both of which show peaks at 10 and 35 solar masses, and one of which shows an additional peak at around 20 solar masses.

Some features, upon a deep analysis, stuck out. When you have a pair of binary black holes, they’re not just going to orbit one another and inspiral, but each black hole can have a spin to it, and those spins, cumulatively, can be either aligned or anti-aligned with the orbital angular momentum of the binary system. When the collaboration members looked at the spins of systems with at least one black hole in the 30-to-40 solar mass range — right where the heaviest “peak” in the mass of black holes is found — they found that spins were only a little more likely to be aligned compared to anti-aligned (about a 65/35 split).

However, for systems that didn’t have a black hole in that mass range (i.e., for all other binary black hole mergers), they found that spins were far more likely to be aligned compared to anti-aligned, showing an impressive 87/13 split. If you model the formation of stars that evolve into black holes, you expect that the spins of the stars (and the spins of the resultant black holes) should be preferentially aligned with their binary orbits, but if you model black holes that merge together as part of trinary (or richer) systems, you expect that the post-merger spin will be much more random with respect to any remaining members. This was suggested in a paper back in 2016, and appears to be consistent with the latest data. Perhaps the “peak” at 35 solar masses is due to mergers of previous black holes that produced at least one member of between 30 and 40 solar masses? It’s an intriguing idea, and one that’s suggested (but not proven) by the current data.

At left, an isolated system, formed from two original members of a binary star system, tends to produce black holes aligned with the orbital motion of the original progenitor stars, leading to black hole mergers with aligned spins. However, for dynamically captured black holes, or for black holes arising from trinary (or richer) systems, those rules and tidal effects don’t apply as strongly, producing a closer to 50-50 split of aligned versus anti-aligned spins.

Thus far, here in 2025, LIGO and the other gravitational wave observatories around the world have continued to take data, discovering approximately 100 additional gravitational wave events (mostly black hole-black hole mergers) that aren’t included in the papers that were just released. In less than 10 short years, we’ve gone from, “we think gravitational waves exist, but we’ve never seen one” to being able to:

• measure hundreds of gravitational wave events,
• pinpoint where on the sky they occur,
• infer the population of stellar mass black holes in the Universe,
• including where there are gaps and peaks in the mass distribution,
• and even to uncover information about the correlations between the black hole spins and the merger orbits.

What was once just a pipe dream of astronomers, physicists, and General Relativists has swiftly grown into a robust field of observational astronomy.

At the start of 2025, astronomers had dreams of two successor facilities:

• LIGO II, which would be a ground-based detector (or multiple detectors) with much longer-baseline arms, of 10 km or more, capable of seeing practically every stellar mass black hole-black hole merger within the observable Universe.
• And LISA, the Laser Interferometer Space Antenna, which would allow the detection of more massive black hole mergers, including intermediate mass and some supermassive black hole mergers, for the first time.

This photograph, taken at LIGO Livingston in Louisiana, shows a perspective of looking “down” one of the two perpendicular 4 kilometer arms through which laser light is reflected many times and brought together to construct an interference pattern that’s sensitive to the presence of gravitational waves. With a detector that has arms ten times as long, we’d be sensitive to such events at much greater distances, as well as to orbiting objects with periods that take up to 10 times longer, allowing us to fill in the gap between what LIGO and LISA are sensitive to. The NSF’s “LIGO II” would allow us to close that gap: either partially or wholly.

Instead of those dreams that look forward to continued advances at the frontier of science, however, gravitational wave astronomers are instead facing the extinction of their own field right as it’s poised to take off. The catastrophic proposed FY2026 budget contains a $9 billion cut to the National Science Foundation, with specific instructions to close down one of the two main LIGO facilities. As one astrophysicist put it, degrading LIGO’s observations of gravitational waves in this fashion is tantamount to “killing a newborn baby,” or as another quipped, it’s a “senseless, irrational thing to do… like trying to fly a plane with only one wing.”

When you couple the proposed National Science Foundation cuts with NASA’s redirection of priorities away from science and instead towards militarized projects like nuclear activity on the Moon, it becomes apparent that the status of the United States as a world leader in physics and astrophysics is more precarious than ever, with even the upcoming Habitable Worlds Observatory under threat. If we abandon this new form of science now, while it’s still in its infancy, progress will likely be set back by decades, if not an entire generation or more. And that’s a pity, because the awe and wonder that this era of gravitational wave astronomy has brought to us is truly unprecedented.

Still, despite the external pressures and threats of withheld funding, there is no diminishing the achievements of gravitational wave astronomy in the last decade. One cannot help but be simultaneously humbled and inspired by how far we’ve come both scientifically and technologically in the realm of gravitational wave detection. After all we’ve learned so much in such a short time, and we’ve done it with a new form of astronomy that, for 100 years, was no more than an unproved prediction of our theory of gravity.

The Universe is full of black holes, and for the first time, we have direct, data-driven estimates of just how many there are and of their mass distribution. All of this was only made possible by the new science of gravitational wave astronomy, which is thriving at a greater level than ever before. Even as the very field itself is at risk of a premature termination, the legacy of what we’ve already accomplished, and the hope it gives us all for the future of science, can never be erased.