A young, massive planet is orbiting in an unusual place in its star system, and it’s leading researchers to revive a long-debated view of how giant planets can form.

The protoplanet, nine times the mass of Jupiter, is too far away from its star to have formed by accreting matter piece by piece, images suggest. Instead, the massive world probably formed all at once in a violent implosion of gas and dust, researchers report April 4 in Nature Astronomy.

“My first reaction was, there’s no way this can be true,” says Thayne Currie, an astrophysicist at the Subaru Telescope headquartered in Hilo, Hawaii.

For years, astronomers have debated the ways in which giant planets might form (SN: 12/3/10). In the “core accretion” story, a planet starts out as small bits of matter within a disk of gas, dust and ice swirling around a young star. The clumps continue to accrete other matter, growing to become the core of the planet. Out past a certain distance from the star, that core then accumulates a thick blanket of hydrogen and helium, turning it into a bloated, gassy world.

But the new planet, orbiting a star called AB Aurigae, is in the outskirts of its system, where there’s less matter to gather into a core. In this position, the core can’t become massive enough to create its gaseous envelope. The planet’s remote location, Currie and colleagues argue, makes it more likely to form via “disk instability,” where the disk around the star breaks into planet-sized fragments. The fragments then rapidly collapse in on themselves, drawn together by their own gravity, and clump together, forming a giant planet.
Using the Subaru Telescope atop Mauna Kea, Currie and colleagues observed AB Aurigae periodically from 2016 to 2020. NASA’s Hubble Space Telescope also observed the star repeatedly over 13 years. Looking at all these images, the team saw a bright spot next to the star. The bright clump was a clear protoplanet, named AB Aur b, orbiting nearly 14 billion kilometers from its star — roughly 3 times as far as Neptune is from the sun.

In the images, AB Aur b looked like it was straight out of a simulation of planet formation by disk instability, Currie says. Except it was real.
“For the longest time, I never believed that planet formation by disk instability could actually work,” he says.

Because AB Aur b is still growing, embedded in the young star’s disk, it could help to explain how the handful of known massive planets orbiting far from their stars formed.

“We only know maybe a few dozen total of these types of planets,” says Quinn Konopacky, an astrophysicist at the University of California, San Diego who was not involved in the research. “Every single one that we find is basically precious.”

It’s difficult to distinguish whether a planet formed by core accretion or disk instability through observations alone, Konopacky says. The fact that AB Aur b is at such a wide separation from its star is “good evidence” that disk instability is what’s happening, she says. Still, “I think that there’s a lot more work to be done and other ways that we can try to assess if that’s what’s going on in the system.”

Both Konopacky and Currie say this research represents only the second direct observation of a protoplanet (SN: 7/2/18). Oftentimes, researchers have trouble distinguishing an actual forming planet from a planetary disk.

The recently launched James Webb Space Telescope could help researchers understand these anomalous gas giants very distant from their stars by studying the AB Aurigae system and others like it, Currie says (SN: 1/24/22). “I think this will spur a lot of debates and follow-up studies by other researchers.”

The windy and chaotic remains surrounding recently exploded stars may be launching the fastest particles in the universe.

Highly magnetic neutron stars known as pulsars whip up a fast and strong magnetic wind. When charged particles, specifically electrons, get caught in those turbulent conditions, they can be boosted to extreme energies, astrophysicists report April 28 in the Astrophysical Journal Letters. What’s more, those zippy electrons can then go on to boost some ambient light to equally extreme energies, possibly creating the very high-energy gamma-ray photons that led astronomers to detect these particle launchers in the first place.

“This is the first step in exploring the connection between the pulsars and the ultrahigh-energy emissions,” says astrophysicist Ke Fang of the University of Wisconsin, Madison, who was not involved in this new work.

Last year, researchers with the Large High Altitude Air Shower Observatory, or LHAASO, in China announced the discovery of the highest-energy gamma rays ever detected, up to 1.4 quadrillion electron volts (SN: 2/2/21). That’s roughly 100 times as energetic as the highest energies achievable with the world’s premier particle accelerator, the Large Hadron Collider near Geneva. Identifying what’s causing these and other extremely high-energy gamma rays could point, literally, to the locations of cosmic rays — the zippy protons, heavier atomic nuclei and electrons that bombard Earth from locales beyond our solar system.
Some gamma rays are thought to originate in the same environs as cosmic rays. One way they’re produced is that cosmic rays, shortly after being launched, can slam into relatively low-energy ambient photons, boosting them to high-energy gamma rays. But the electrically charged cosmic rays are buffeted by galactic magnetic fields, which means they don’t travel in a straight line, thus complicating efforts to trace the zippy particles back to their source. Gamma rays, however, are impervious to magnetic fields, so astrophysicists can trace their unwavering paths back to their origins — and figure out where cosmic rays are created.

To that end, the LHAASO team traced the hundreds of gamma-ray photons that it detected to 12 spots on the sky. While the team identified one spot as the Crab Nebula, the remnant of a supernova about 6,500 light-years from Earth, the researchers suggested that the rest could be associated with other sites of stellar explosions or even young massive star clusters (SN: 6/24/19).

In the new study, astrophysicist Emma de Oña Wilhelmi and colleagues zeroed in one of those possible points of origin: pulsar wind nebulas, the clouds of turbulence and charged particles surrounding a pulsar. The researchers weren’t convinced such locales could create such high-energy particles and light, so they set out to show through calculations that pulsar wind nebulas weren’t the sources of extreme gamma rays. “But to our surprise, we saw at the very extreme conditions, you can explain all the sources [that LHAASO saw],” says de Oña Wilhelmi, of the German Electron Synchrotron in Hamburg.

The young pulsars at the heart of these nebulas — no more than 200,000 years old — can provide all that oomph because of their ultrastrong magnetic fields, which create a turbulent magnetic bubble called a magnetosphere.

Any charged particles moving in an intense magnetic field get accelerated, says de Oña Wilhelmi. That’s how the Large Hadron Collider boosts particles to extreme energies (SN: 4/22/22). A pulsar-powered accelerator, though, can boost particles to even higher energies, the team calculates. That’s because the electrons escape the pulsar’s magnetosphere and meet up with the material and magnetic fields from the stellar explosion that created the pulsar. These magnetic fields can further accelerate the electrons to even higher energies, the team finds, and if those electrons slam into ambient photons, they can boost those particles of light to ultrahigh energies, turning them into gamma rays.

“Pulsars are definitely very powerful accelerators,” Fang says, with “several places where particle acceleration can happen.”

And that could lead to a bit of confusion. Gamma-ray telescopes have pretty fuzzy vision. For example, LHASSO can make out details only as small as about half the size of the full moon. So the gamma-ray sources that the telescope detected look like blobs or bubbles, says de Oña Wilhelmi. There could be multiple energetic sources within those blobs, unresolved to current observatories.

“With better angular resolution and better sensitivity, we should be able to identify what [and] where the accelerator is,” she says. A few future observatories — such as the Cherenkov Telescope Array and the Southern Wide-field Gamma-ray Observatory — could help, but they’re several years out.

That’s one small stem for a plant, one giant leap for plant science.

In a tiny, lab-grown garden, the first seeds ever sown in lunar dirt have sprouted. This small crop, planted in samples returned by Apollo missions, offers hope that astronauts could someday grow their own food on the moon.

But plants potted in lunar dirt grew more slowly and were scrawnier than others grown in volcanic material from Earth, researchers report May 12 in Communications Biology. That finding suggests that farming on the moon would take a lot more than a green thumb.
“Ah! It’s so cool!” says University of Wisconsin–Madison astrobotanist Richard Barker of the experiment.

“Ever since these samples came back, there’s been botanists that wanted to know what would happen if you grew plants in them,” says Barker, who wasn’t involved in the study. “But everyone knows those precious samples … are priceless, and so you can understand why [NASA was] reluctant to release them.”

Now, NASA’s upcoming plans to send astronauts back to the moon as part of its Artemis program have offered a new incentive to examine that precious dirt and explore how lunar resources could support long-term missions (SN: 7/15/19).

The dirt, or regolith, that covers the moon is basically a gardener’s worst nightmare. This fine powder of razor-sharp bits is full of metallic iron, rather than the oxidized kind that is palatable to plants (SN: 9/15/20). It’s also full of tiny glass shards forged by space rocks pelting the moon. What it is not full of is nitrogen, phosphorus or much else plants need to grow. So, even though scientists have gotten pretty good at coaxing plants to grow in fake moon dust made of earthly materials, no one knew whether newborn plants could put down their delicate roots in the real stuff.

To find out, a trio of researchers at the University of Florida in Gainesville ran experiments with thale cress (Arabidopsis thaliana). This well-studied plant is in the same family as mustards and can grow in just a tiny clod of material. That was key because the researchers had only a little bit of the moon to go around.

The team planted seeds in tiny pots that each held about a gram of dirt. Four pots were filled with samples returned by Apollo 11, another four with Apollo 12 samples and a final four with dirt from Apollo 17. Another 16 pots were filled with earthly volcanic material used in past experiments to mimic moon dirt. All were grown under LED lights in the lab and watered with a broth of nutrients.
“Nothing really compared to when we first saw the seedlings as they were sprouting in the lunar regolith,” says Anna-Lisa Paul, a plant molecular biologist. “That was a moving experience, to be able to say that we’re watching the very first terrestrial organisms to grow in extraterrestrial materials, ever. And it was amazing. Just amazing.”

Plants grew in all the pots of lunar dirt, but none grew as well as those cultivated in earthly material. “The healthiest ones were just smaller,” Paul says. The sickliest moon-grown plants were tiny and had purplish pigmentation — a red flag for plant stress. Plants grown in Apollo 11 samples, which had been exposed on the lunar surface the longest, were most stunted.

Paul and colleagues also inspected the genes in their mini alien Eden. “By seeing what kind of genes are turned on and turned off in response to a stress, that shows you what tools plants are pulling out of their metabolic toolbox to deal with that stress,” she says. All plants grown in moon dirt pulled out genetic tools typically seen in plants struggling with stress from salt, metals or reactive oxygen species (SN: 9/8/21).

Apollo 11 seedlings had the most severely stressed genetic profile, offering more evidence that regolith exposed to the lunar surface longer — and therefore littered with more impact glass and metallic iron — is more toxic to plants.

Future space explorers could choose the site for their lunar habitat accordingly. Perhaps lunar dirt could also be modified somehow to make it more comfortable for plants. Or plants could be genetically engineered to feel more at home in alien soil. “We can also choose plants that do better,” Paul says. “Maybe spinach plants, which are very salt-tolerant, would have no trouble growing in lunar regolith.”

Barker isn’t daunted by the challenges promised by this first attempt at lunar gardening. “There’s many, many steps and pieces of technology to be developed before humanity can really engage in lunar agriculture,” he says. “But having this particular dataset is really important for those of us that believe it’s possible and important.”

As health officials continue their investigation of unexplained cases of liver inflammation in children, what is known is still outpaced by what isn’t.

At least 500 cases of hepatitis from an unknown cause have been reported in children in roughly 30 countries, according to health agencies in Europe and the United States. As of May 18, 180 cases are under review in 36 U.S. states and territories.

Many of the children have recovered. But some cases have been severe, with more than two dozen of the kids needing liver transplants. At least a dozen children have died, including five in the United States.
The illnesses have mainly been seen in children under age 5. So far, health agencies have ruled out common causes of hepatitis, while reporting that some of the children have tested positive for adenovirus. That pathogen — which infects basically everyone, usually without serious issues — is not known as a primary cause of liver damage. For some children who are positive, officials have identified the particular adenovirus: type 41.

But there are several reasons why pinning an adenovirus as the sole hepatitis culprit doesn’t fully add up, researchers say. Nor is it clear whether the recent cases indicate an uptick in hepatitis illnesses, or just more attention. Though the cases seem to have popped up out of nowhere, “we’ve seen similar rare severe liver disease like this in children,” says Anna Peters, a pediatric transplant hepatologist at the Cincinnati Children’s Hospital Medical Center.

Most of all, it’s important for parents to remember that the cases described so far “are a rare phenomenon,” Peters says. “Parents shouldn’t panic.”

Hepatitis in children
Hepatitis is an inflammation of the liver that can interfere with the organ’s many functions, including filtering blood and regulating clotting. Three hepatitis viruses, called hepatitis A, B and C, are common causes of the illness in the United States. Hepatitis A is spread when infected fecal material reaches the mouth. Children can get B and C when it’s transmitted from a pregnant person to an infant. There are vaccines available for A and B but not C. An excessive dose of acetaminophen can also cause hepatitis in children.

The signs of hepatitis can include nausea, fatigue, a yellow tinge to skin and eyes, urine that’s darker than usual and stools that are light-colored, among other symptoms. Hepatitis that arises quickly usually resolves, whereas some cases progress more slowly and lead to liver damage over time.

It’s rare for a child to develop sudden liver failure. An estimated 500 to 600 cases occur each year in the United States, and around 30 percent of those are “indeterminate,” meaning a cause isn’t found, according to the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition.

The indeterminate category of sudden liver failure has been known for some time, Peters says, and that subset of cases has similarities to the hepatitis under investigation. There hasn’t been data reported yet on whether the recent cases represent an increase over what’s been seen in prior years, Peters says. “Maybe this is just increased recognition of something that’s been going on.”

Adenovirus as a suspect
Not all of the children with hepatitis have been positive for adenovirus, nor have they all been tested. The European Centre for Disease Prevention and Control, or ECDC, has reported that of 151 cases tested, 90 were positive, or 60 percent. The last dispatch from the U.K. Health Security Agency, from early May, noted that 126 samples out of 163 had been tested, with 91, or 72 percent, positive. Further analysis of 18 cases identified adenovirus type 41.

Adenoviruses commonly infect people, typically causing colds, bronchitis or other respiratory illnesses. Two types, adenovirus 40 and 41, target the intestines, leading to gastrointestinal symptoms such as vomiting and diarrhea.

“All of these types, including this prime suspect type 41, have been detected everywhere continuously,” says virologist Adriana Kajon of the Lovelace Biomedical Research Institute in Albuquerque. “All of them have existed and have been reported continuously for decades.”

People usually recover from an adenovirus infection. The exception is those whose immune systems aren’t functioning properly — then, an infection can be serious. There have been cases of hepatitis from adenovirus in immunocompromised children, but the kids under investigation are not immunocompromised.

There are several curious details about the adenovirus findings. For example, the children who have tested positive for the virus had low levels in their blood. In cases of hepatitis from adenovirus, “the virus levels are very, very high,” Peters says.

Nor has adenovirus been found in the liver. In a study of nine children with the hepatitis in Alabama who were positive for adenovirus in blood samples, researchers studied liver tissue from six of the kids. There was no sign of the virus in the liver, the researchers report May 6 in Morbidity and Mortality Weekly Report.

“It’s very hard to implicate a virus that you cannot find in the crime scene,” Kajon said May 3 at a symposium for clinical virology in West Palm Beach, Fla.

Another oddity: There doesn’t seem to be a path of viral spread from one location to another. That’s unlike SARS-CoV-2, the virus that causes COVID-19, “where there was quite clearly a spread from some epicenter originally,” says virologist and clinician Andrew Tai of the University of Michigan Medical School in Ann Arbor, who treats patients with liver disease.

An adenovirus culprit is not out of the realm of possibility, but “virus associations with diseases are always hard to really nail down and prove,” says virologist Katherine Spindler, also of the University of Michigan Medical School. “We’re going to be hard pressed to say this is due to adenovirus 41, let alone adenovirus.”

Considering COVID-19
Looming over all of this is the possibility that a many-magnitudes-larger infectious disease outbreak, COVID-19, could have a part.

Researchers have found that SARS-CoV-2 impacts the liver in milder and more severe cases of COVID-19. There is evidence that the liver becomes inflamed in children and adults during an infection. Liver failure can occur with a severe bout of COVID-19. And children who develop multisystem inflammatory syndrome in children, or MIS-C, after COVID-19 can have hepatitis as part of that syndrome.

Peters and her colleagues have described yet another way SARS-CoV-2 could put the liver at risk. The team reported the case of a young female patient from the fall of 2020, who had sudden liver failure about three weeks after a SARS-CoV-2 infection. She did not have MIS-C. A liver biopsy showed signs of autoimmune hepatitis, a type in which the body attacks its own liver, Peters and colleagues report in the May Journal of Pediatric Gastroenterology and Nutrition Reports. The patient recovered after treatment with anti-inflammatory medication.

Some of the children with hepatitis have tested positive for SARS-CoV-2, but more haven’t. The ECDC has reported that 20 of 173 cases tested were positive for SARS-CoV-2, while the U.K. Health Security Agency detected the virus in 24 of 132 samples tested.

However, there have been very little data reported on whether the children have antibodies to SARS-CoV-2, which would be evidence of a past infection. (Vaccination hasn’t been available to most of these young children.) The ECDC found that of 19 cases tested, 14 were positive for antibodies to the virus.

One theory is that an earlier SARS-CoV-2 infection has set the stage for an unexpected response to an adenovirus or other infection. With people no longer minimizing contact, the spread of adenoviruses and other respiratory viruses is returning to prepandemic levels.

“We are possibly seeing the return of these forgotten pathogens, so to speak, aggravating disease or eliciting severe inflammation resulting from some kind of preexisting condition,” which could be COVID-19, Kajon said on May 3.

“I cannot think of anything else that has had a worldwide impact that can explain cases of hepatitis in places as distant as the U.K. and Argentina,” Kajon says.

With SARS-CoV-2, researchers have a good sense of how it causes disease during an active infection, Peters says. But for the longer-term effects, “everybody is still sorting things out.”

On her deep-sea dives, wildlife biologist Angela Ziltener of the University of Zurich often noticed Indo-Pacific bottlenosed dolphins doing something intriguing. The dolphins (Tursiops aduncus) would line up to take turns brushing their bodies against corals or sea sponges lining the seafloor. After more than a decade as an “adopted” member of the pod — a status that let Ziltener get up close without disturbing the animals — she and her team may have figured out why the animals behave this way: The dolphins may use corals and sea sponges as their own private pharmacies.

The invertebrates make antibacterial compounds — as well as others with antioxidant or hormonal properties — that are probably released into the waters of the Northern Red Sea when dolphins make contact, Ziltener and colleagues report May 19 in iScience. So the rubbing could help dolphins maintain healthy skin.
Ziltener captured video showing members of the pod using corals as if they were a bath brush, swimming through to rub various parts of their bodies. Oftentimes it’s a peaceful social gathering. “It’s not like they’re fighting each other for the turn,” Ziltener says. “No, they wait and then they go through.” Other times, an individual dolphin will arrive at a patch of coral on its own.

But the dolphins won’t buff their bodies against just any corals, Ziltener says. They’re picky, primarily rubbing up against gorgonian corals (Rumphella aggregata) and leather corals (Sarcophyton sp.), as well as a kind of sea sponge (Ircinia sp.).

Ziltener and colleagues analyzed one-centimeter slices taken from wild corals and sponges. The team identified 17 compounds overall, including 10 with antibacterial or antimicrobial activity. It’s possible that as the dolphins swim through the corals, the compounds help protect the animals from skin irritations or infections, says coauthor Gertrud Morlock, an analytical chemist at Justus Liebig University Giessen in Germany.
Other animals, including chimpanzees, can self-medicate (SN: 11/3/90). Marine biologist Jeremy Kiszka of Florida International University in Miami says the new study convinces him that the dolphins are using corals and sea sponges for that purpose. But, he says, additional experiments are necessary to prove the link. Lab tests, for instance, could help identify the types of bacteria that the compounds might work against.

Ziltener agrees there’s more to be done. For instance, it’s also possible that in addition to prevention, dolphins use corals and sea sponges to treat active skin infections, she says, but the team has yet to see proof of a coral cure. Next up though, Ziltener says, is figuring out whether dolphins prefer to rub specific body parts on specific corals in such an “underwater spa.”

The U.S. defense and intelligence communities are taking unidentified flying objects, officially known as unidentified aerial phenomena, seriously. And some researchers think the scientific community should too.

On May 17, the U.S. Congress held its first public hearing about these objects in decades (SN: 6/26/71). Two Pentagon officials described efforts to catalog and analyze sightings, many by military personnel such as pilots, of the unexplained phenomena because of their potential threat to national security.

Scott Bray, the deputy director of naval intelligence, shared new details on a database of images and videos that now includes about 400 reports of sightings of unidentified phenomena from 2004 to 2021. While officials were able to attribute some of the sightings to artifacts of certain sensors or other mundane explanations, there were others the officials “can’t explain,” Bray said.

Bray stressed that nothing in the database or studied by a task force set up to investigate the sightings “would suggest it’s anything nonterrestrial in origin.”
Both Bray and Ronald Moultrie, the undersecretary of defense for intelligence and security, identified “insufficient data” as a barrier to understanding what the unidentified phenomena are. “That’s one of the challenges we have,” Moultrie said.

That’s something that other scientists can help with, say astrobiologists Jacob Haqq Misra and Ravi Kopparapu.

Science News spoke with Haqq Misra, of Blue Marble Space Institute of Science in Seattle, and Kopparapu, of NASA’s Goddard Space Flight Center in Greenbelt, Md., to learn more about how and why. Their answers have been edited for brevity and clarity.

What are unidentified aerial phenomena?
Haqq Misra: “What are they” is the billion-dollar question. We don’t know what they are, and that’s what makes them interesting.

Unidentified aerial phenomena, or UAP, is the term that the military has been using. It’s a little different from the term UFO in the sense that a phenomenon could be something that’s not necessarily a physical solid object. So UAP is maybe a more all-encompassing term.

Should we scientifically study them? Why?
Kopparapu: Yes. We conduct scientific studies of unknown phenomena all the time. This should not be any different. The most critical point to remember is that when conducting those studies, we should not let our speculations drive the conclusions. The collected data should do it.

Haqq Misra: As scientists, what we should do is study things that we don’t understand.

With UAP, there seem to be some anomalous observations that are difficult to explain. Maybe they’re a sign of something like new physics, or maybe it’s just instrumental artifacts that we don’t understand or things that birds are doing.

It could be anything, but any of those possibilities, anything from the most extreme to the most mundane, would teach us something.

So there’s the scientific curiosity. And it’s also about safety for pilots too, especially if there’s something in the sky that pilots are seeing that they consider a flight safety risk.

How can we study these phenomena?
Haqq Misra: The problem with studying UAP so far is that all of the data are held by the government. From the hearing, there does seem to be a plan to declassify some data, once it’s been vetted for possible security risks, but I’m not holding my breath for that to happen soon. It was nice to hear, though.

The reality is if you want to understand a particular set of data, you need to know something about the instrument that collected the data. Military instruments are probably classified for good reason, for our safety. I think we’re not going to get the kind of data from the government that we need to scientifically answer the question. Even if you had that data, from the government or commercial pilots or others, it has not been intentionally collected. These have been accidental, sporadic observations.

So what you would need is to set up a network of detectors all around the world. Ideally, you’d have ground-based sensors and you’d have satellite coverage. It’s not enough for someone to just see something. You need to measure a detection with multiple sensors and multiple wavelengths.

Kopparapu: Some of these are transient events. We need, for example, fast-tracking cameras and optical, infrared and radar observations to collect more data to find patterns in the events’ behaviors.

And we need to share such data with scientists so that independent groups can reach a consensus. This is how science progresses. There are some initiatives from academics in this direction, so that is a good sign.

What are some possible next steps for the scientific community for studying them?
Haqq Misra: There are some groups that are trying to build detectors now. Fundraising is the hardest part. [The nonprofit] UAPx is one, and the Galileo Project [at Harvard University] is another.

And this was underscored in the hearing, but stigma has been a big problem. It seems like the military is trying to not only streamline the reporting process but also destigmatize it. That’s important for science too. If that starts to change more in the culture, that would go a long way.

Kopparapu: I think the scientific study of UAP should not be stigmatized. There should be open discussions, comments and constructive criticisms that can help further the study of UAP.

There should be discussions about how and which kinds of instruments are needed to collect data. The focus should be on collecting and sharing the data and then commenting on the topic.

How did you get interested in this topic?
Kopparapu: Over a couple of years, I read several articles either dismissing or advocating for a particular explanation regarding UAP. Then I started digging into it, and I found physicist James McDonald’s “Science in Default” report from 1969. That one particular report about UFOs changed my perspective. It was written similar to how we write our scientific articles. That resonated with me as a scientist, and I started to think that a science investigation is the only way we can understand UAP.

Haqq Misra: I got interested in this subject because I’m an astrobiologist and other people asked me about UFOs. UFOs are not necessarily an astrobiology topic, because we don’t know what they are. But lots of people think that they’re extraterrestrials. And I felt a little silly, being an astrobiologist and having nothing to say.

So I went to Carl Sagan’s files, and I realized that even though he lived decades before me, there are things in his files that we’re talking about now, that are related to airborne anomalies seen by pilots.

Ultimately, I realized for a scientist who wants to understand what’s going on with this UFO thing, there’s a lot of noise to sift through. There’s a lot of public discourse about other topics like crop circles, alien abductions and paranormal stories that muddy the waters, and the more we can be clear about the specific aerial anomalies that we’re talking about, the more we can actually solve the problem.

Gut parasites in large plant eaters like caribou thrive out of sight and somewhat out of mind. But these tiny tummy tenants can have big impacts on the landscape that their hosts travel through.

Digestive tract parasites in caribou can reduce the amount that their hosts eat, allowing for more plant growth in the tundra where the animals live, researchers report in the May 17 Proceedings of the National Academy of Sciences. The finding reveals that even nonlethal infections can have reverberating effects through ecosystems.
Interactions between species have long been known to ripple through ecosystems, indirectly impacting other parts of the food web. When predators eat herbivores, for example, a reduction in plant-eating mouths leads to changes in the plant community. This is how sea otters, for example, can encourage kelp growth by feeding on herbivorous urchins (SN: 3/29/21).

“Anytime you have a change in species interactions that changes what the animals are doing on the landscape, it can influence their impact on the ecosystem,” says Amanda Koltz, an ecologist at Washington University in St. Louis.

When parasites and pathogens kill their hosts, it can have a similar effect to predators on ecosystems. A prime example is the rinderpest virus, which in the late 19th century devastated populations of ruminants — buffalo, antelope, cattle — in sub-Saharan Africa. Once wildebeest populations in East Africa were spared further infection following the vaccination of cattle and the eradication of the virus, their exploding numbers trimmed the grass back in the Serengeti and led to other landscape changes.

But unlike rinderpest, most infections aren’t lethal. Nonlethal parasite infections are pervasive in ruminants — plant eaters that play key roles in shaping vegetation on land. Koltz and her team wondered if changes to a ruminant’s overall health or behavior from a chronic parasitic infection could also induce changes in the surrounding plant community.
The researchers looked to caribou (Rangifer tarandus). Using data from published studies, Koltz and her team developed a series of mathematical simulations to test how caribou survival, reproduction and feeding rate could be influenced by stomach worm (Ostertagia spp.) infections.

The scientists then calculated how these effects could alter the total mass of and population changes in the caribou, parasites and plants. The simulations predict that not only could lethal infections trigger a cascade leading to more plant mass, but also nonlethal infections had just as large an effect. Sickened caribou that ate less or experienced a drop in reproduction rate led to an increase in plant mass when compared with a scenario with no parasites.

The team also analyzed data from 59 studies on 18 species of ruminants and their parasites, gathering information on how the parasites impact host feeding rates and body mass. The analysis found that chronic parasitic infections generally cause many types of herbivores to eat less, also reducing their body mass and fat reserves.

Indirect ecological ramifications from parasitic infections could be common in ruminants all over the world, the researchers conclude.

The study “highlights that there are widespread interactions that we’re not considering in ecosystem contexts quite yet, but we should be,” Koltz says.

Globally, parasites face an uncertain future with fast environmental changes — like climate change and habitat loss from changes in land use — altering relationships with their hosts, potentially leading to many parasite extinctions. “How such changes in host-parasite interactions might disrupt the structure and functioning of ecosystems is a topic that we should be thinking about,” Koltz says.

The findings also are “going to change how we think about what controls ecosystems,” says Oswald Schmitz, a population ecologist at Yale University who was not involved in the research. “Maybe it isn’t predators that are necessarily controlling the ecosystem, maybe the parasites are more important,” he says. “And so, what we really need to do is more research that disentangles [this].”

Scientists are rapidly gaining a better understanding of parasites’ ubiquity and abundance, says Joshua Grinath, an ecologist at Idaho State University in Pocatello. “Now we are challenged with understanding the roles of parasites within ecological communities and ecosystems.”

For millennia, the universe did a pretty good job of keeping its secrets from science.

Ancient Greeks thought the universe was a sphere of fixed stars surrounding smaller spheres carrying planets around the central Earth. Even Copernicus, who in the 16th century correctly replaced the Earth with the sun, viewed the universe as a single solar system encased by the star-studded outer sphere.

But in the centuries that followed, the universe revealed some of its vastness. It contained countless stars agglomerated in huge clusters, now called galaxies.

Then, at the end of the 1920s, the cosmos disclosed its most closely held secret of all: It was getting bigger. Rather than static and stable, an everlasting and ever-the-same entity encompassing all of reality, the universe continually expanded. Observations of distant galaxies showed them flying apart from each other, suggesting the current cosmos to be just the adult phase of a universe born long ago in the burst of a tiny blotch of energy.

It was a surprise that shook science at its foundations, undercutting philosophical preconceptions about existence and launching a new era in cosmology, the study of the universe. But even more surprising, in retrospect, is that such a deep secret had already been suspected by a mathematician whose specialty was predicting the weather.
A century ago this month (May 1922), Russian mathematician-meteorologist Alexander Friedmann composed a paper, based on Einstein’s general theory of relativity, that outlined multiple possible histories of the universe. One such possibility described cosmic expansion, starting from a singular point. In essence, even without considering any astronomical evidence, Friedmann had anticipated the modern Big Bang theory of the birth and evolution of the universe.

“The new vision of the universe opened by Friedmann,” writes Russian physicist Vladimir Soloviev in a recent paper, “has become a foundation of modern cosmology.”

Friedmann was not well known at the time. He had graduated in 1910 from St. Petersburg University in Russia, having studied math along with some physics. In graduate school he investigated the use of math in meteorology and atmospheric dynamics. He applied that expertise in aiding the Russian air force during World War I, using math to predict the optimum release point for dropping bombs on enemy targets.

After the war, Friedmann learned of Einstein’s general theory of relativity, which describes gravity as a manifestation of the geometry of space (or more accurately, spacetime). In Einstein’s theory, mass distorts spacetime, producing spacetime “curvature,” which makes masses appear to attract each other.

Friedmann was especially intrigued by Einstein’s 1917 paper (and a similar paper by Willem de Sitter) applying general relativity to the universe as a whole. Einstein found that his original equations allowed the universe to grow or shrink. But he considered that unthinkable, so he added a term representing a repulsive force that (he thought) would keep the size of the cosmos constant. Einstein concluded that space had a positive spatial curvature (like the surface of a ball), implying a “closed,” or finite universe.

Friedmann accepted the new term, called the cosmological constant, but pointed out that for various values of that constant, along with other assumptions, the universe might exhibit very different behaviors. Einstein’s static universe was a special case; the universe might also expand forever, or expand for a while, then contract to a point and then begin expanding again.

Friedmann’s paper describing dynamic universes, titled “On the Curvature of Space,” was accepted for publication in the prestigious Zeitschrift für Physik on June 29, 1922.

Einstein objected. He wrote a note to the journal contending that Friedmann had committed a mathematical error. But the error was Einstein’s. He later acknowledged that Friedmann’s math was correct, while still denying that it had any physical validity.

Friedmann insisted otherwise.

He was not just a pure mathematician, oblivious to the physical meanings of his symbols on paper. His in-depth appreciation of the relationship between equations and the atmosphere persuaded him that the math meant something physical. He even wrote a book (The World as Space and Time) delving deeply into the connection between the math of spatial geometry and the motion of physical bodies. Physical bodies “interpret” the “geometrical world,” he declared, enabling scientists to test which of the various possible geometrical worlds humans actually inhabit. Because of the physics-math connection, he averred, “it becomes possible to determine the geometry of the geometrical world through experimental studies of the physical world.”

So when Friedmann derived solutions to Einstein’s equations, he translated them into the possible physical meanings for the universe. Depending on various factors, the universe could be expanding from a point, or from a finite but smaller initial state, for instance. In one case he envisioned, the universe began to expand at a decelerating rate, but then reached an inflection point, whereupon it began expanding at a faster and faster rate. At the end of the 20th century, astronomers measuring the brightness of distant supernovas concluded that the universe had taken just such a course, a shock almost as surprising as the expansion of the universe itself. But Friedmann’s math had already forecast such a possibility.
No doubt Friedmann’s deep appreciation for the synergy of abstract math and concrete physics prepared his mind to consider the notion that the universe could be expanding. But maybe he had some additional help. Although he was the first scientist to seriously propose an expanding universe, he wasn’t the first person. Almost 75 years before Friedmann’s paper, the poet Edgar Allan Poe had published an essay (or “prose poem”) called Eureka. In that essay Poe described the history of the universe as expanding from the explosion of a “primordial particle.” Poe even described the universe as growing and then contracting back to a point again, just as envisioned in one of Friedmann’s scenarios.

Although Poe had studied math during his brief time as a student at West Point, he had used no equations in Eureka, and his essay was not recognized as a contribution to science. At least not directly. It turns out, though, that Friedmann was an avid reader, and among his favorite authors were Dostoevsky and Poe. So perhaps that’s why Friedmann was more receptive to an expanding universe than other scientists of his day.

Today Friedmann’s math remains at the core of modern cosmological theory. “The fundamental equations he derived still provide the basis for the current cosmological theories of the Big Bang and the accelerating universe,” Israeli mathematician and historian Ari Belenkiy noted in a 2013 paper. “He introduced the fundamental idea of modern cosmology — that the universe is dynamic and may evolve in different manners.”

Friedmann emphasized that astronomical knowledge in his day was insufficient to reveal which of the possible mathematical histories the universe has chosen. Now scientists have much more data, and have narrowed the possibilities in a way that confirms the prescience of Friedmann’s math.

Friedmann did not live to see the triumphs of his insights, though, or even the early evidence that the universe really does expand. He died in 1925 from typhoid fever, at the age of 37. But he died knowing that he had deciphered a secret about the universe deeper than any suspected by any scientist before him. As his wife remembered, he liked to quote a passage from Dante: “The waters I am entering, no one yet has crossed.”

Deep in the human brain, a very specific kind of cell dies during Parkinson’s disease.

For the first time, researchers have sorted large numbers of human brain cells in the substantia nigra into 10 distinct types. Just one is especially vulnerable in Parkinson’s disease, the team reports May 5 in Nature Neuroscience. The result could lead to a clearer view of how Parkinson’s takes hold, and perhaps even ways to stop it.

The new research “goes right to the core of the matter,” says neuroscientist Raj Awatramani of Northwestern University Feinberg School of Medicine in Chicago. Pinpointing the brain cells that seem to be especially susceptible to the devastating disease is “the strength of this paper,” says Awatramani, who was not involved in the study.

Parkinson’s disease steals people’s ability to move smoothly, leaving balance problems, tremors and rigidity. In the United States, nearly 1 million people are estimated to have Parkinson’s. Scientists have known for decades that these symptoms come with the death of nerve cells in the substantia nigra. Neurons there churn out dopamine, a chemical signal involved in movement, among other jobs (SN: 9/7/17).

But those dopamine-making neurons are not all equally vulnerable in Parkinson’s, it turns out.

“This seemed like an opportunity to … really clarify which kinds of cells are actually dying in Parkinson’s disease,” says Evan Macosko, a psychiatrist and neuroscientist at Massachusetts General Hospital in Boston and the Broad Institute of MIT and Harvard.
The tricky part was that dopamine-making neurons in the substantia nigra are rare. In samples of postmortem brains, “we couldn’t survey enough of [the cells] to really get an answer,” Macosko says. But Abdulraouf Abdulraouf, a researcher in Macosko’s laboratory, led experiments that sorted these cells, figuring out a way to selectively pull the cells’ nuclei out from the rest of the cells present in the substantia nigra. That enrichment ultimately led to an abundance of nuclei to analyze.

By studying over 15,000 nuclei from the brains of eight formerly healthy people, the researchers further sorted dopamine-making cells in the substantia nigra into 10 distinct groups. Each of these cell groups was defined by a specific brain location and certain combinations of genes that were active.

When the researchers looked at substantia nigra neurons in the brains of people who died with either Parkinson’s disease or the related Lewy body dementia, the team noticed something curious: One of these 10 cell types was drastically diminished.

These missing neurons were identified by their location in the lower part of the substantia nigra and an active AGTR1 gene, lab member Tushar Kamath and colleagues found. That gene was thought to serve simply as a good way to identify these cells, Macosko says; researchers don’t know whether the gene has a role in these dopamine-making cells’ fate in people.

The new finding points to ways to perhaps counter the debilitating diseases. Scientists have been keen to replace the missing dopamine-making neurons in the brains of people with Parkinson’s. The new study shows what those cells would need to look like, Awatramani says. “If a particular subtype is more vulnerable in Parkinson’s disease, maybe that’s the one we should be trying to replace,” he says.

In fact, Macosko says that stem cell scientists have already been in contact, eager to make these specific cells. “We hope this is a guidepost,” Macosko says.

The new study involved only a small number of human brains. Going forward, Macosko and his colleagues hope to study more brains, and more parts of those brains. “We were able to get some pretty interesting insights with a relatively small number of people,” he says. “When we get to larger numbers of people with other kinds of diseases, I think we’re going to learn a lot.”

One common chemical in sunscreen can have devastating effects on coral reefs. Now, scientists know why.

Sea anemones, which are closely related to corals, and mushroom coral can turn oxybenzone — a chemical that protects people against ultraviolet light — into a deadly toxin that’s activated by light. The good news is that algae living alongside the creatures can soak up the toxin and blunt its damage, researchers report in the May 6 Science.

But that also means that bleached coral reefs lacking algae may be more vulnerable to death. Heat-stressed corals and anemones can eject helpful algae that provide oxygen and remove waste products, which turns reefs white. Such bleaching is becoming more common as a result of climate change (SN: 4/7/20).
The findings hint that sunscreen pollution and climate change combined could be a greater threat to coral reefs and other marine habitats than either would be separately, says Craig Downs. He is a forensic ecotoxicologist with the nonprofit Haereticus Environmental Laboratory in Amherst, Va., and was not involved with the study.

Previous work suggested that oxybenzone can kill young corals or prevent adult corals from recovering after tissue damage. As a result, some places, including Hawaii and Thailand, have banned oxybenzone-containing sunscreens.

In the new study, environmental chemist Djordje Vuckovic of Stanford University and colleagues found that glass anemones (Exaiptasia pallida) exposed to oxybenzone and UV light add sugars to the chemical. While such sugary add-ons would typically help organisms detoxify chemicals and clear them from the body, the oxybenzone-sugar compound instead becomes a toxin that’s activated by light.

Anemones exposed to either simulated sunlight or oxybenzone alone survived the length of the experiment, or 21 days, the team showed. But all anemones exposed to fake sunlight while submersed in water containing the chemical died within 17 days.
The anemones’ algal friends absorbed much of the oxybenzone and the toxin that the animals were exposed to in the lab. Anemones lacking algae died days sooner than anemones with algae.

In similar experiments, algae living inside mushroom coral (Discosoma sp.) also soaked up the toxin, a sign that algal relationships are a safeguard against its harmful effects. The coral’s algae seem to be particularly protective: Over eight days, no mushroom corals died after being exposed to oxybenzone and simulated sunlight.

It’s still unclear what amount of oxybenzone might be toxic to coral reefs in the wild. Another lingering question, Downs says, is whether other sunscreen components that are similar in structure to oxybenzone might have the same effects. Pinning that down could help researchers make better, reef-safe sunscreens.