NASA’s DART spacecraft just smashed into an asteroid — on purpose

Mission control rooms rarely celebrate crash landings. But the collision of NASA’s DART spacecraft with an asteroid was a smashing success.

At about 7:15 p.m. EDT on September 26, the spacecraft hurtled into Dimorphos, an asteroid moonlet orbiting a larger space rock named Didymos. The mission’s goal was to bump Dimorphos slightly closer to its parent asteroid, shortening its 12-hour orbit around Didymos by several minutes.

The Double Asteroid Redirection Test, or DART, is the world’s first attempt to change an asteroid’s motion by ramming a space probe into it (SN: 6/30/20). Neither Dimorphos nor Didymos poses a threat to Earth. But seeing how well DART’s maneuver worked will reveal how easy it is to tamper with an asteroid’s trajectory — a strategy that could protect the planet if a large asteroid is ever discovered on a collision course with Earth.

“We don’t know of any large asteroids that would be considered a threat to Earth that are coming any time in the next century,” says DART team member Angela Stickle, a planetary scientist at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. “The reason that we are doing something like DART is because there are asteroids that we haven’t discovered yet.”
Astronomers have spotted almost all the kilometer-size asteroids in the solar system that could end civilization if they hit Earth, says Jessica Sunshine, a planetary scientist at the University of Maryland in College Park who’s also on the DART team. But when it comes to space rocks around 150 meters wide, like Dimorphos, “we only know where about 40 percent of those are,” Sunshine says. “And that is something that, if it did hit, would certainly take out a city.”

Dimorphos is a safe asteroid to give an experimental nudge, says Mark Boslough, a physicist at Los Alamos National Laboratory in New Mexico who has studied planetary protection but is not involved in DART. “It’s not on a collision course” with Earth, he says, and DART “can’t hit it hard enough to put it on a collision course.” The DART spacecraft weighs only as much as a couple of vending machines, whereas Dimorphos is thought to be nearly as hefty as Egypt’s Great Pyramid of Giza.

After a 10-month voyage, DART met up with Didymos and Dimorphos near their closest approach to Earth, about 11 million kilometers away. Up until the very end of its journey, DART could see only the larger asteroid, Didymos. But about an hour before impact, DART spotted Dimorphos in its field of view. Using its onboard camera, the spacecraft steered itself toward the asteroid moonlet and slammed into it at some 6.1 kilometers per second, or nearly 14,000 miles per hour.
DART’s camera feed went dark after impact. But another probe nearby is expected to have caught the collision on camera. The Light Italian CubeSat for Imaging of Asteroids rode to Dimorphos aboard DART but detached a couple of weeks before impact to watch the event from a safe distance. Its mission was to whiz past Dimorphos about three minutes after DART’s impact to snap pictures of the crash site and the resulting plume of asteroid debris launched into space. The probe is expected to beam images of DART’s demise back to Earth within a couple of days.

“I was absolutely elated, especially as we saw the camera getting closer and just realizing all the science that we’re going to learn,” said Pam Melroy, NASA Deputy Administrator, after the impact. “But the best part was seeing, at the end, that there was no question there was going to be an impact, and to see the team overjoyed with their success.”
DART’s impact is expected to shove Dimorphos into a closer, shorter orbit around Didymos. Telescopes on Earth can clock the timing of that orbit by watching how the amount of light from the double asteroid system changes as Dimorphos passes in front of and behind Didymos.

“It’s really a beautifully conceived experiment,” Boslough says. In the coming weeks, dozens of telescopes across every continent will watch Dimorphos to see how much DART changed its orbit. The Hubble and James Webb space telescopes may also get images.
“It’ll be really interesting to see what comes out,” says Amy Mainzer, a planetary scientist at the University of Arizona in Tucson who is not involved in DART. “Asteroids have a way of surprising us,” she says, because it’s hard to know a space rock’s precise chemical makeup and internal structure based on observations from Earth. So Dimorphos’ motion post-impact may not exactly match researchers’ expectations.

The DART team will compare data on Dimorphos’ new orbit with their computer simulations to see how close those models were to predicting the asteroid’s actual behavior and tweak them accordingly. “If we can get our models to reproduce what actually happened, then you can use those models to [plan for] other scenarios that might show up in the future” — like the discovery of a real killer asteroid, says DART team member Wendy Caldwell, a mathematician and planetary scientist at Los Alamos National Laboratory.

“No matter what happens,” she says, “we will get information that is valuable to the scientific community and to the planetary defense community.”

In Maya society, cacao use was for everyone, not just royals

In ancient Maya civilization, cacao wasn’t just for the elites.

Traces of the sacred plant show up in ceramics from all types of neighborhoods and dwellings in and around a former Maya city, researchers report September 26 in the Proceedings of the National Academy of Sciences. The finding suggests that, contrary to previous thinking, cacao was consumed at every social level of Maya society.

“Now we know that the rituals the elite depict with cacao were likely played out, like Thanksgiving, like any other ritual, by everyone,” says Anabel Ford, an archaeologist at the University of California, Santa Barbara.
Cacao — which chocolate is made from — was sacred to the ancient Maya, consumed in rituals and used as a currency. The cacao tree (Theobroma cacao) itself was linked to Hun Hunahpu, the maize god. Previous research found cacao in ceremonial vessels and elite burials, suggesting that its use was restricted to those at the top.

To explore the extent to which cacao was used in broader Maya society, Ford and colleagues examined 54 ceramic shards dating from A.D. 600 to 900 (SN: 9/27/18). The shards come from jars, mixing bowls, serving plates and vases thought to be drinking vessels. All the pieces were found in residential and ceremonial civic areas of varying size and status from city centers, foothills, upland areas and the valley around the former Maya city of El Pilar, on the present-day border of Guatemala and Belize.

To identify cacao, the researchers searched for theophylline, a compound found in trace amounts in the plant. The team found the compound on more than half of the samples, on all types of ceramics and distributed throughout social contexts.

Future research will move beyond who consumed cacao and explore the role of farmers in managing the critical resource. “A better question is to understand who grew it,” Ford says, because those people probably had greater access to the prized commodity.

A protogalaxy in the Milky Way may be our galaxy’s original nucleus

The Milky Way left its “poor old heart” in and around the constellation Sagittarius, astronomers report. New data from the Gaia spacecraft reveal the full extent of what seems to be the galaxy’s original nucleus — the ancient stellar population that the rest of the Milky Way grew around — which came together more than 12.5 billion years ago.

“People have long speculated that such a vast population [of old stars] should exist in the center of our Milky Way, and Gaia now shows that there they are,” says astronomer Hans-Walter Rix of the Max Planck Institute for Astronomy in Heidelberg, Germany.
The Milky Way’s ancient heart is a round protogalaxy that spans nearly 18,000 light-years and possesses roughly 100 million times the mass of the sun in stars, or about 0.2 percent of the Milky Way’s current stellar mass, Rix and colleagues report in a study posted September 7 at arXiv.org.

“This study really helps to firm up our understanding of this very, very, very young stage in the Milky Way’s life,” says Vasily Belokurov, an astronomer at the University of Cambridge who was not involved in the work. “Not much is really known about this period of the Milky Way’s life,” he says. “We’ve seen glimpses of this population before,” but the new study gives “a bird’s-eye view of the whole structure.”

Most stars in the Milky Way’s central region abound with metals, because the stars originated in a crowded metropolis that earlier stellar generations had enriched with those metals through supernova explosions. But Rix and his colleagues wanted to find the exceptions to the rule, stars so metal-poor they must have been born well before the rest of the galaxy’s stellar denizens came along — what Rix calls “a needle-in-a-haystack exercise.”

His team turned to data from the Gaia spacecraft, which launched in 2013 on a mission to chart the Milky Way (SN: 6/13/22). The astronomers searched about 2 million stars within a broad region around the galaxy’s center, which lies in the constellation Sagittarius, looking for stars with metal-to-hydrogen ratios no more than 3 percent of the sun’s.

The astronomers then examined how those stars move through space, retaining only the ones that don’t dart off into the vast halo of metal-poor stars engulfing the Milky Way’s disk. The end result: a sample of 18,000 ancient stars that represents the kernel around which the entire galaxy blossomed, the researchers say. By accounting for stars obscured by dust, Rix estimates that the protogalaxy is between 50 million and 200 million times as massive as the sun.

“That’s the original core,” Rix says, and it harbors the Milky Way’s oldest stars, which he says probably have ages exceeding 12.5 billion years. The protogalaxy formed when several large clumps of stars and gas conglomerated long ago, before the Milky Way’s first disk — the so-called thick disk — arose (SN: 3/23/22).

The protogalaxy is compact, which means little has disturbed it since its formation. Smaller galaxies have crashed into the Milky Way, augmenting its mass, but “we didn’t have any later mergers that deeply penetrated into the core and shook it up, because then the core would be larger now,” Rix says.

The new data on the protogalaxy even capture the Milky Way’s initial spin-up — its transition from an object that didn’t rotate into one that now does. The oldest stars in the proto–Milky Way barely revolve around the galaxy’s center but dive in and out of it instead, whereas slightly younger stars show more and more movement around the galactic center. “This is the Milky Way trying to become a disk galaxy,” says Belokurov, who saw the same spin-up in research that he and a colleague reported in July.

Today, the Milky Way is a giant galaxy that spins rapidly — each hour our solar system speeds through 900,000 kilometers of space as we race around the galaxy’s center. But the new study shows that the Milky Way got its start as a modest protogalaxy whose stars still shine today, stars that astronomers can now scrutinize for further clues to the galaxy’s birth and early evolution.

Drumming woodpeckers use similar brain regions as songbirds

Songbirds get a lot of love for their dulcet tones, but drummers may start to steal some of that spotlight.

Woodpeckers, which don’t sing but do drum on trees, have brain regions that are similar to those of songbirds, researchers report September 20 in PLOS Biology. The finding is surprising because songbirds use these regions to learn their songs at an early age, yet it’s not clear if woodpeckers learn their drum beats (SN: 9/16/21). Whether woodpeckers do or not, the result suggests a shared evolutionary origin for both singing and drumming.
The ability to learn vocalizations by listening to them, just like humans do when learning to speak, is a rare trait in the animal kingdom. Vocal learners, such as songbirds, hummingbirds and parrots, have independently evolved certain clusters of nerve cells called nuclei in their forebrains that control the ability. Animals that don’t learn vocally are thought to lack these brain features.

While it’s commonly assumed that other birds don’t have these nuclei, “there’s thousands of birds in the world,” says Matthew Fuxjager, a biologist at Brown University in Providence, R.I. “While we say these brain regions only exist in these small groups of species, nobody’s really looked in a lot of these other taxa.”

Fuxjager and his colleagues examined the noggins of several birds that don’t learn vocally to check if they really did lack these brain nuclei. Using molecular probes, the team checked the bird brains for activity of a gene called parvalbumin, a known marker of the vocal learning nuclei. Many of the birds, including penguins and flamingos, came up short, but there was one exception — male and female woodpeckers, which had three spots in their brains with high parvalbumin activity.

Though woodpeckers don’t sing, they do perform a rapid drumming on trees and house gutters to defend their territories or find mates. This drumming is different from the drilling the birds do to find food. When the team found brain nuclei similar to songbirds in woodpeckers, Fuxjager was immediately intrigued. “I thought right away it’s probably related to drumming,” he says.

The researchers subjected downy woodpeckers (Dryobates pubescens) in the wild to audio recordings of drumming from other woodpeckers. This faux territorial invasion sparked an aggressive drumming response from the birds, which were then captured and euthanized to have their recent brain activity analyzed. Sure enough, the same regions identified by earlier lab tests had been activated in the drummers.

The brains of bird vocalists and drummers evolved separately, but the similarity of the analyzed regions hints at a common origin. “It suggests that there are common themes about how you develop these complex behaviors,” says Bradley Colquitt, a biologist at the University of California, Santa Cruz who was not involved in the study. The neural circuitry formed by these nuclei most likely developed from an ancestral circuit controlling movement, Colquitt says.

“Birdsong is basically the brain controlling muscles in a vocal organ called the syrinx,” Fuxjager says. These sophisticated movements are not unlike the swift head-and-neck motions involved in drumming.

Whether drumming is learned like birdsong remains an open question that the team is now exploring. Future work will also look at how woodpeckers’ brains are wired, how these nuclei control drumming and how the brain regions’ role in drumming evolved across woodpecker species, Fuxjager says.

This new study “uncovers another species that we can add to our comparative efforts” to better understand how complex behaviors evolve, Colquitt says. “It is a preview into potentially exciting evolutionary neurobiology.” Now that woodpeckers have joined the band of important musical birds, it looks like the drummers may soon get their chance to shine.

Fossil finds put gibbons in Asia as early as 8 million years ago

Small-bodied, long-armed apes called gibbons swing rapidly through the trees, far outpacing scientists’ attempts to decipher these creatures’ evolutionary story.

Now, a partial upper jaw and seven isolated teeth found near a southwestern Chinese village have added bite to a suggestion that the earliest known gibbons hung out there about 7 million to 8 million years ago, researchers report in the October Journal of Human Evolution..

Those fossils, as well as 14 teeth previously found at the same site and a nearby site, belong to an ancient hylobatid species called Yuanmoupithecus xiaoyuan, say paleoanthropologist Xueping Ji of the Kunming Natural History Museum of Zoology in China and colleagues. Hylobatids, a family of apes that includes about 20 species of living gibbons and a black-furred gibbon called the siamang, inhabit tropical forests from northeastern India to Indonesia.
Ji’s group has presumed that Y. xiaoyuan was an ancient gibbon since introducing the species in a 2006 Chinese publication. But additional fossils were needed to check that suspicion.

The newly discovered upper jaw piece — found by a local villager and given to Ji during fieldwork around a decade ago — contains four teeth, including a partly erupted molar that helped researchers identify it as the remains of an infant that died before reaching age 2.

Comparisons with modern apes and fossils of ancient primates peg Y. xiaoyuan as the oldest known gibbon and cast doubt on a two-year-old report that a roughly 13-million-year-old molar tooth found in northern India came from a hylobatid, the team says (SN: 9/8/20). The fossil found in India, assigned to a species dubbed Kapi ragnagarensis, represents an extinct group of South Asian primates that were not closely related to present-day apes, the scientists say.

Prior DNA analyses of living primates suggested that hylobatids diverged from other apes in Africa between 22 million and 17 million years ago. But it’s a mystery when gibbon ancestors arrived in Eurasia, says paleoanthropologist and study coauthor Terry Harrison of New York University. A gap in the fossil record of about 10 million years exists between the estimated time when hylobatids emerged in or near Africa and evidence of Y. xiaoyuan in Asia.

Genetic evidence also indicates that gibbon species today shared a common ancestor around 8 million years ago, when Y. xiaoyuan was alive. “It could be that [Y. xiaoyuan] is the ancestor of all later gibbons,” Harrison says. If not, Y. xiaoyuan was closely related to a modern gibbon ancestor, he suspects.

Bumps and depressions on chewing surfaces and other tooth and jaw features of Y. xiaoyuan look much like those of living gibbons, Ji’s team says. Some traits of the fossil species were precursors of slightly different traits in modern gibbons, the researchers suggest.

Based on molar sizes, they estimate that Y. xiaoyuan weighed about six kilograms, similar to gibbons today. Molar structure indicates that Y. xiaoyuan focused on eating fruits, like most gibbon species today, Harrison says.

Ji’s group “makes a very good case that [Y. xiaoyuan] is a hylobatid,” says paleoanthropologist David Alba of Institut Català de Paleontologia Miquel Crusafont in Barcelona.

But the evolutionary status of K. ragnagarensis remains unsettled because only a single tooth from that species has been found, says Alba, who did not participate in the new study.

Video shows the first fox known to fish for food

The fox froze. Inches from his paws, frenzied, spawning carp writhed in the shallow water along a reservoir’s shore. In a sudden flash of movement, the fox dove nose-first into the water, emerging with a large carp wriggling in his mouth.

In March 2016, two researchers in Spain watched as a male red fox (Vulpes vulpes) stalked and caught 10 carp over a couple of hours. The event, described in a study published August 18 in Ecology, seems to be the first recorded instance of a fox fishing, the researchers say. The discovery makes red foxes just the second type of canid — the group that includes wolves and dogs — known to hunt fish.
“Seeing the fox hunting carp one after another was incredible,” says ecologist Jorge Tobajas of the University of Córdoba. “We have been studying this species for years, but we never expected something like this.”

Tobajas and his colleague Francisco Díaz-Ruiz of the University of Málaga stumbled across the fishing fox while surveying a site for a different project. The fox first caught their attention because it didn’t immediately flee when it spotted the researchers. Seizing the opportunity, Tobajas and Díaz-Ruiz decided to hide nearby and see what the fox was up to.

Their curiosity turned into excitement after the fox caught its first fish. “The most surprising thing was to see how the fox hunted many carp without making any mistakes,” Tobajas says. “This made us realize that it was surely not the first time he had done it.”
Instead of immediately guzzling down all of the fish, the fox hid most of its catch and appeared to share at least one fish with a female fox, possibly its mate.

Fish remains have been spotted in the scat of foxes before. But scientists weren’t sure whether foxes had caught the fish themselves or were simply scavenging dead fish. This research confirms that some foxes fish for their food, says Thomas Gable, a wildlife ecologist at the University of Minnesota in Minneapolis who wasn’t involved in the research.

“I would be shocked if this was the only fox to have learned how to fish,” Gable says.

Wolves living on the Pacific coast of North America and in Minnesota are the only other canids known to fish (SN: 2/11/20). The fact that two canid species living on separate continents both fish opens the possibility that the behavior might be more common than previously thought, Gable says.

For Tobajas, the fishing fox is an example of how much scientists still don’t know about the natural world, even for species that live fairly close with humans. “The red fox is a very common species and is in many cases a bit hated,” he says. Foxes sometimes attack pets or livestock and are considered a pest in many places. But “observations like this show us that it a fascinating and very intelligent animal.”

This environmentally friendly quantum sensor runs on sunlight

A new take on highly sensitive magnetic field sensors ditches the power-hungry lasers that previous devices have relied on to make their measurements and replaces them with sunlight. Lasers can gobble 100 watts or so of power — like keeping a bright lightbulb burning. The innovation potentially untethers quantum sensors from that energy need. The result is an environmentally friendly prototype on the forefront of technology, researchers report in an upcoming issue of Physical Review X Energy.
The big twist is in how the device uses sunlight. It doesn’t use solar cells to convert light into electricity. Instead, the sunlight does the job of the laser’s light, says Jiangfeng Du, a physicist at the University of Science and Technology of China in Hefei.

Quantum magnetometers often include a powerful green laser to measure magnetic fields. The laser shines on a diamond that contains atomic defects (SN: 2/26/08). The defects result when nitrogen atoms replace some of the carbon atoms that pure diamonds are made of. The green laser causes the nitrogen defects to fluoresce, emitting red light with an intensity that depends on the strength of the surrounding magnetic fields.

The new quantum sensor needs green light too. There’s plenty of that in sunlight, as seen in the green wavelengths reflected from tree leaves and grass. To collect enough of it to run their magnetometer, Du and colleagues replaced the laser with a lens 15 centimeters across to gather sunlight. They then filtered the light to remove all colors but green and focused it on a diamond with nitrogen atom defects. The result is red fluorescence that reveals magnetic field strengths just as laser-equipped magnetometers do.
Changing energy from one type to another, as happens when solar cells collect light and produce electricity, is an inherently inefficient process (SN: 7/26/17). The researchers claim that avoiding the conversion of sunlight to electricity to run lasers makes their approach three times more efficient than would be possible with solar cells powering lasers.

“I’ve never seen any other reports that connect solar research to quantum technologies,” says Yen-Hung Lin, a physicist at the University of Oxford who was not involved with the study. “It might well ignite a spark of interest in this unexplored direction, and we could see more interdisciplinary research in the field of energy.”

Quantum devices sensitive to other things, like electric fields or pressure, could also benefit from the sunlight-driven approach, the researchers say. In particular, space-based quantum technology might use the intense sunlight available outside Earth’s atmosphere to provide light tailored for quantum sensors. The remaining light, in wavelengths that the quantum sensors don’t use, could be relegated to solar cells that power electronics to process the quantum signals.

The sunlight-driven magnetometer is just a first step in the melding of quantum and environmentally sustainable technology. “In the current state, this device is primarily for developmental purposes,” Du says. “We expect that the devices will be used for practical purposes. But there [is] lots of work to be done.”

Ancient ‘demon ducks’ may have been undone by their slow growth

Giant flightless birds called mihirungs were the biggest birds to ever stride across what is now Australia. The animals, which weighed up to hundreds of kilograms, died out about 40,000 years ago. Now researchers might have a better idea why.

The birds may have grown and reproduced too slowly to withstand pressures from humans’ arrival on the continent, researchers report August 17 in the Anatomical Record.

Mihirungs are sometimes called “demon ducks” because of their great size and close evolutionary relationship with present-day waterfowl and game birds. The flightless, plant-eating birds lived for more than 20 million years.
Over that time, some species evolved into titans. Take Stirton’s thunderbird (Dromornis stirtoni). It lived about 7 million years ago, stood 3 meters tall and could exceed 500 kilograms in weight, making it the largest-known mihirung and a contender for the largest bird ever to live.

Most research on mihirungs has been on their anatomy and evolutionary relationships with living birds. Little is known about the animals’ biology, such as how long they took to grow and mature, says Anusuya Chinsamy-Turan, a paleobiologist at the University of Cape Town in South Africa.

So Chinsamy-Turan and colleagues at Flinders University in Adelaide, Australia took samples from 20 fossilized leg bones of D. stirtoni, from animals of varying life stages.
“Even after millions of years of fossilization, the microscopic structure of fossil bones generally remains intact,” and it can be used to decipher important clues about extinct animals’ biology, Chinsamy-Turan says.

The team examined the thin bone slices under a microscope, detailing the presence or absence of growth marks. These marks provide information on how fast the bone grew while the birds were alive.

D. stirtoni took 15 years or more to reach full size, the team found. It probably became sexually mature a few years before that, based on the timing of a shift from rapidly growing bone to a slower-growing form that’s thought to be associated with reaching reproductive age.

These results differ from the team’s earlier analysis of the bones of another mihirung, Genyornis newtoni. That species — the last-known mihirung — was less than half the size of D. stirtoni. It lived as recently as about 40,000 years ago and was a contemporary of the continent’s earliest human inhabitants. G. newtoni grew up much faster than its giant relative, reaching adult size in one to two years and growing a bit more in the following years and possibly reproducing then.

This difference in how fast mihirung species that were separated by millions of years developed may have been an evolved response to Australia developing a drier, more variable climate over the last few million years, the researchers say. When resources are unpredictable, growing and reproducing quickly can be advantageous.

Even so, that seeming pep in the developmental step of more recent mihirungs was still slower than that of the emus they lived alongside. Emus grow up quickly, reaching adult size in less than a year and reproducing not long after, laying large numbers of eggs.

This difference may explain why G. newtoni went extinct shortly after hungry humans arrived in Australia, yet emus continue to thrive today, the team says. Even though over millions of years, mihirungs as a group seem to have adapted to growing and reproducing quicker than they used to, it wasn’t enough to survive the arrival of humans, who probably ate the birds and their eggs, the researchers conclude.

“Slowly growing animals face dire consequences in terms of their reduced ability to recover from threats in their environments,” Chinsamy-Turan says.

The scientists’ research on other giant, extinct, flightless birds thought to have met their end thanks to humans — such as the dodos of Mauritius (Raphus cucullatus) and the largest of Madagascar’s elephant birds (Vorombe titan) — shows that they too grew relatively slowly (SN: 8/29/17).

“It is very interesting to see this pattern repeating again and again with many large, flightless bird groups,” says Thomas Cullen, a paleoecologist at Carleton University in Ottawa who was not involved with the new study.

Modern ratite birds seem to be the exception in their ability to handle similar pressures, he says. Other ratites besides emus that have survived until the present day — such as cassowaries and ostriches — also grow and reproduce quickly (SN: 4/25/14).

Physicists dispute a claim of detecting a black hole’s ‘photon ring’

The first image of a black hole may conceal treasure — but physicists disagree about whether it’s been found.

A team of scientists say they’ve unearthed a photon ring, a thin halo of light around the supermassive black hole in the galaxy M87. If real, the photon ring would provide a new probe of the black hole’s intense gravity. But other scientists dispute the claim. Despite multiple news headlines suggesting the photon ring has been found, many physicists remain unconvinced.
Unveiled in 2019 by scientists with the Event Horizon Telescope, or EHT, the first image of a black hole revealed a doughnut-shaped glow from hot matter swirling around the black hole’s dark silhouette (SN: 4/10/19). But according to Einstein’s general theory of relativity, a thinner ring should be superimposed on that thick doughnut. This ring is produced by photons, or particles of light, that orbit close to the black hole, slung around by the behemoth’s gravity before escaping and zinging toward Earth.

Thanks to this circumnavigation, the photons should provide “a fingerprint of gravity,” more clearly revealing the black hole’s properties, says astrophysicist Avery Broderick of the University of Waterloo and the Perimeter Institute for Theoretical Physics in Canada. He and his colleagues, a subset of scientists from the EHT collaboration, used a new method to tease out that fingerprint, they report in the Aug. 10 Astrophysical Journal.

Creating images with EHT isn’t a simple point-and-shoot affair (SN: 4/10/19). Researchers stitch together data from EHT’s squad of observatories scattered across the globe, using various computational techniques to reconstruct an image. Broderick and colleagues created a new black hole image assuming it featured both a diffuse emission and a thin ring. On three out of four days of observations, the data better matched an image with the added thin ring than one without the ring.

But that method has drawn harsh criticism. “The claim of a photon ring detection is preposterous,” says physicist Sam Gralla of the University of Arizona in Tucson.

A main point of contention: The photon ring is brighter than expected, emitting around 60 percent of the light in the image. According to predictions, it should be more like 20 percent. “That’s a giant red flag,” says physicist Alex Lupsasca of Vanderbilt University in Nashville. More light should come from the black hole’s main glowing doughnut than from the thin photon ring.

This unexpected brightness, Broderick and colleagues say, occurs because some of the light from the main glow gets lumped in with the photon ring. So the ring’s apparent brightness doesn’t depend only on the light coming from the ring. The researchers note that the same effect appeared when testing the method on simulated data.

But that mishmash of purported photon ring light with other light doesn’t make for a very convincing detection, critics say. “If you want to claim that you’ve seen a photon ring, I think you have to do a better job than this,” says astrophysicist Dan Marrone of the University of Arizona, a member of the EHT collaboration who was not a coauthor on the new paper.

The new result suggests only that an added thin ring gives a better match to the data, Marrone says, not whether that shape is associated with the photon ring. So it raises the question of whether scientists are seeing a photon ring at all, or just picking out an unrelated structure in the image.

But Broderick argues that the features of the ring — the fact that its size and location are as expected and are consistent day-to-day — support the photon ring interpretation.

Meanwhile, in a similar, independent analysis, Gralla and physicist Will Lockhart, also of the University of Arizona, find no evidence for a photon ring, they report in a paper submitted August 22 at arXiv.org. Their analysis differed from Broderick and colleagues’ in part because it limited how bright the photon ring could be.

To convincingly detect the photon ring, some scientists propose adding telescopes in space to the EHT’s crew of observatories (SN: 3/18/20). The farther apart the telescopes in the network are, the finer details they may be able to pick out — potentially including the photon ring.

“If there were a photon ring detection,” Lupsasca says, “that would be the best thing in physics this year, if not for many years.”

The curious case of the 471-day coronavirus infection

As omicron subvariant BA.5 continues to drive the coronavirus’ spread in the United States, I’ve been thinking about what could come next. Omicron and its offshoots have been topping the variant charts since last winter. Before that, delta reigned.

Scientists have a few ideas for how new variants emerge. One involves people with persistent infections — people who test positive for the virus over a prolonged period of time. I’m going to tell you about the curious case of a person infected with SARS-CoV-2 for at least 471 days and what can happen when infections roil away uncontrolled.
That lengthy infection first came onto epidemiologist Nathan Grubaugh’s radar in the summer of 2021. His team had been analyzing coronavirus strains in patient samples from Yale New Haven Hospital when Grubaugh spotted something he had seen before. Known only as B.1.517, this version of the virus never got a name like delta or omicron, nor rampaged through communities quite like its infamous relatives.

Instead, after springing up somewhere in North America in early 2020, B.1.517 tooled around in a handful of regions around the world, even sparking an outbreak in Australia. But after April 2021, B.1.517 seemed to sputter, one of the who-knows-how-many viral lineages that flare up and then eventually fizzle.

B.1.517 might have been long forgotten, shouldered aside by the latest variant to stake a claim in local communities. “And yet we were still seeing it,” Grubaugh says. Even after B.1.517 had petered out across the country, his team noticed it cropping up in patient samples. The same lineage, every few weeks, like clockwork, for months.

One clue was the samples’ specimen ID. The code on the B.1.517 samples was always the same, Grubaugh’s team noticed. They had all come from a single patient.

That patient, a person in their 60s with a history of cancer, relapsed in November of 2020. That was right around when they first tested positive for SARS-CoV-2. After seeing B.1.517 show up again and again in their samples, Grubaugh worked with a clinician to get the patient’s permission to analyze their data.
Ultimately, the patient has remained infected for 471 days (and counting), Grubaugh, Yale postdoctoral researcher Chrispin Chaguza and their team reported last month in a preliminary study posted at medRxiv.org. Because of deteriorating health and a desire to maintain their anonymity, the patient was not willing to be interviewed, and Grubaugh has no direct contact with them.

But all those samples collected over all those days told an incredible tale of viral evolution. Over about 15 months, at least three genetically distinct versions of the virus had rapidly evolved inside the patient, the team’s analyses suggested.

Each version had dozens of mutations and seemed to coexist in the patient’s body. “Honestly, if any one of these were to emerge in a population and begin transmitting, we would be calling it a new variant,” Grubaugh says.

That scenario is probably rare, he says. After all, lots of prolonged infections have likely occurred during the pandemic, and only a handful of concerning variants have emerged. But the work does suggest that persistent viral infections can provide a playground for speedy evolutionary experimentation — perhaps taking advantage of weakened immune systems.

Grubaugh’s work is “probably the most detailed look we’ve had at a single, persistent infection with SARS-CoV-2 so far,” says Tom Friedrich, a virologist at the University of Wisconsin–Madison, who was not involved with the work.
The study supports an earlier finding about a different immunocompromised patient — one with a persistent omicron infection. In that work, researchers documented the evolution of the virus over 12 weeks and showed that its descendant infected at least five other people.

Together, the studies lay out how such infections could potentially drive the emergence of the next omicron.

“I am pretty well convinced that people with persistent infection are important sources of new variants,” Friedrich says.

Who exactly develops these infections remains mysterious. Yes, the virus can pummel people with weakened immune systems, but “not every immunocompromised person develops a persistent infection,” says Viviana Simon, a virologist at the Icahn School of Medicine at Mount Sinai who worked on the omicron infection study.

In fact, doctors and scientists have no idea how common these infections are. “We just don’t really have the numbers,” Simon says. That’s a huge gap for researchers, and something Mount Sinai’s Pathogen Surveillance Program is trying to address by analyzing real-time infection data.

Studying patients with prolonged infections could also tell scientists where SARS-CoV-2 evolution is heading, Friedrich says. Just because the virus evolves within a person doesn’t mean it will spread to other people. But if certain viral mutations tend to arise in multiple people with persistent infections, that could hint that the next big variant might evolve in a similar way. Knowing more about these mutation patterns could help researchers forecast what’s to come, an important step in designing future coronavirus vaccine boosters.
Beyond viral forecasting, Grubaugh says identifying people with prolonged infections is important so doctors can provide care. “We need to give them access to vaccines, monoclonal antibodies and antiviral drugs,” he says. Those treatments could help patients clear their infections.

But identifying persistent infections is easier said than done, he points out. Many places in the world aren’t set up to spot these infections and don’t have access to vaccines or treatments. And even when these are available, some patients opt out. The patient in Grubaugh’s study received a monoclonal antibody infusion about 100 days into their infection, then refused all other treatments. They have not been vaccinated.

Though the patient remained infectious over the course of the study, their variants never spread to the community, as far as Grubaugh knows.

And while untreated chronic infections might spawn new variants, they could emerge in other ways, too, like from animals infected with the virus, from person-to-person transmission in groups of people scientists haven’t been monitoring, or from “something else that maybe none of us has thought of yet,” he says. “SARS-CoV-2 has continued to surprise us with its evolution.”