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Scientists have finally figured out how those arches, loops and whorls formed on your fingertips.

While in the womb, fingerprint-defining ridges expand outward in waves starting from three different points on each fingertip. The raised skin arises in a striped pattern thanks to interactions between three molecules that follow what’s known as a Turing pattern, researchers report February 9 in Cell. How those ridges spread from their starting sites — and merge — determines the overarching fingerprint shape.
Fingerprints are unique and last for a lifetime. They’ve been used to identify individuals since the 1800s. Several theories have been put forth to explain how fingerprints form, including spontaneous skin folding, molecular signaling and the idea that ridge pattern may follow blood vessel arrangements.

Scientists knew that the ridges that characterize fingerprints begin to form as downward growths into the skin, like trenches. Over the few weeks that follow, the quickly multiplying cells in the trenches start growing upward, resulting in thickened bands of skin.

Since budding fingerprint ridges and developing hair follicles have similar downward structures, researchers in the new study compared cells from the two locations. The team found that both sites share some types of signaling molecules — messengers that transfer information between cells — including three known as WNT, EDAR and BMP. Further experiments revealed that WNT tells cells to multiply, forming ridges in the skin, and to produce EDAR, which in turn further boosts WNT activity. BMP thwarts these actions.

To examine how these signaling molecules might interact to form patterns, the team adjusted the molecules’ levels in mice. Mice don’t have fingerprints, but their toes have striped ridges in the skin comparable to human prints. “We turn a dial — or molecule — up and down, and we see the way the pattern changes,” says developmental biologist Denis Headon of the University of Edinburgh.

Increasing EDAR resulted in thicker, more spaced-out ridges, while decreasing it led to spots rather than stripes. The opposite occurred with BMP, since it hinders EDAR production.

That switch between stripes and spots is a signature change seen in systems governed by Turing reaction-diffusion, Headon says. This mathematical theory, proposed in the 1950s by British mathematician Alan Turing, describes how chemicals interact and spread to create patterns seen in nature (SN: 7/2/10). Though, when tested, it explains only some patterns (SN: 1/21/14).

Mouse digits, however, are too tiny to give rise to the elaborate shapes seen in human fingerprints. So, the researchers used computer models to simulate a Turing pattern spreading from the three previously known ridge initiation sites on the fingertip: the center of the finger pad, under the nail and at the joint’s crease nearest the fingertip.
By altering the relative timing, location and angle of these starting points, the team could create each of the three most common fingerprint patterns — arches, loops and whorls — and even rarer ones. Arches, for instance, can form when finger pad ridges get a slow start, allowing ridges originating from the crease and under the nail to occupy more space.

“It’s a very well-done study,” says developmental and stem cell biologist Sarah Millar, director of the Black Family Stem Cell Institute at the Icahn School of Medicine at Mount Sinai in New York City.

Controlled competition between molecules also determines hair follicle distribution, says Millar, who was not involved in the work. The new study, she says, “shows that the formation of fingerprints follows along some basic themes that have already been worked out for other types of patterns that we see in the skin.”

Millar notes that people with gene mutations that affect WNT and EDAR have skin abnormalities. “The idea that those molecules might be involved in fingerprint formation was floating around,” she says.

Overall, Headon says, the team aims to aid formation of skin structures, like sweat glands, when they’re not developing properly in the womb, and maybe even after birth.

“What we want to do, in broader terms, is understand how the skin matures.”

Among some killer whale moms, lifelong feeding for adult sons but not daughters could be a long-term investment play. The delayed payoff? Greater grandmotherly glory.

Females in a quirky population of killer whales off the Pacific Coast of North America let their grown mama’s boys share fish that mom catches. Biologists have known that this pampering continues throughout a son’s life, which can last decades. Grown daughters, often feeding their own offspring, however, don’t get such a bonus.
Scrutinizing decades of data has now revealed what moms sacrifice to lavish a lifetime of food on a son, researchers report February 8 in Current Biology. A mother’s yearly chance of successfully weaning a calf drops by about half after she has a son, says behavioral ecologist Michael Weiss of the Center for Whale Research in Friday Harbor, Wash.

For the moms, “it’s a huge, huge cost that they’re taking on,” Weiss says. It “emphasizes kind of the uniqueness and the intensity of this mother-son bond in killer whales.” For creatures that bear their young in a series, he says, this finding is “our first kind of direct evidence of any animal showing lifetime parental investment.”

These killer whales off the coast of Washington State and British Columbia, in “the southern resident” population of Orcinus orca, don’t migrate. Instead they specialize in feeding year-round on the region’s fish, such as big chinook salmon.

When moms catch a fish, “they do this huge head jerk, and one half of the fish stays in the mouth and the other half kind of trails behind them as they swim on,” Weiss says. A son swimming with her can then grab that other half. “It’s not the son coming up and grabbing the fish out of her mouth,” he says.

The son’s company looks consensual to Weiss. Mothers and sons “spend a lot of time kind of floating at the surface together … just kind of enjoying each other’s company.” Whale watchers need to take care reading interpretations into behavior, he says, but his “intuition from watching them is more about the mom wanting to provide for the son.”

Weiss doesn’t think the decline in new births after producing a son comes from any lack of opportunity to mate. “These whales are really social,” he says. “They’re usually in quite large groups, and usually with at least one sexually mature male around.” When watching them from drones, “we see that social behavior in these whales often involves a lot of sexual behavior,” he says. Nevertheless, all those halved fishes may not give a mom enough nutrition for the demands of whale pregnancy.

Mom’s grandchild tally however can make up for her own limited reproduction as she coddles her sons, the whale records show. Sons don’t have to parent. They just deliver sperm to the right address. Plus, the longer males live, the better, Weiss says. For a few years, genetics suggested that the two oldest males in the southern resident population were siring more than half the new calves.
Female killer whales, however, face more constraints. Killer whale pregnancies last some 18 months. So a Casanova whale’s sister gets preoccupied for a long time producing just one wrinkly not-so-little darling and then nurturing it to independence.

Female killer whales do have a chance to help later generations survive, because the species is among the few nonhuman mammals that experience menopause (SN: 3/5/15; SN: 8/19/13). (Females can stop reproducing in their 30s or 40s, but can live into their 80s).

Whether moms in other killer whale populations also routinely and consequentially serve dinner for grown sons isn’t an easy question to answer. Weiss wonders whether the same male whales in another place, perhaps with more abundant fish, would still reduce their mothers’ success at later births.

No other killer whale population’s records can match the depth of the ones Weiss used, says cetacean biologist Eve Jourdain of the University of Oslo. Her research focuses on killer whales around Norway that follow the seasonal movements of herring and other food bonanzas.

Jourdain doesn’t recall moms flinging fish, but she watches the whales herding local herring into big fish balls of swimming dinner. Which they share. So there may be other kinds of food-based bonding yet to be analyzed.

If you’re a museum aficionado itching for a new place to explore, 2023 has you covered. New science museums and exhibitions are opening, and some zoos are expanding. This sampling of destinations to check out in the new year or beyond has something for everyone, whether you’re a wildlife lover, space nerd or history buff.

Grand Egyptian Museum
Outside Cairo
Opens: To be announced

2022 marked the 100th anniversary of the discovery of King Tut’s tomb (SN: 11/19/22, p. 14). Now, thousands of artifacts from the tomb — along with tens of thousands of other archaeological finds from ancient Egypt — will go on display when this museum, located within view of the Pyramids of Giza, opens. More than a decade in the making, it will be one of the largest archaeological museums in the world.
Richard Gilder Center for Science, Education and Innovation
American Museum of Natural History
New York City
Opens: February 17

This multistory building will add tons of new exhibit space to the more than 150-year-old museum. Visitors can explore an insectarium that includes one of the world’s largest displays of live leaf-cutting ants and come face-to-face with dozens of butterfly species in a vivarium. Meanwhile, the interconnectedness of life will be on display in the immersive, 360-degree “Invisible Worlds” exhibition.
Galápagos Islands
Houston Zoo
Opens: April 2023

If you can’t travel to the Galápagos Islands, a trip to Texas might be the next best thing. Giant tortoises, iguanas, penguins, sea lions, sharks and other creatures will inhabit this new exhibition that will re-create the land and marine ecosystems of the archipelago made famous by Charles Darwin.

Kansas City Zoo Aquarium
Opens: September 2023

The 34 exhibits of this new aquarium will allow visitors to glimpse a wide variety of ocean locales without having to leave the Midwest. Underwater residents will include sea urchins and sea anemones in a warm intertidal zone, fish swimming in a coral reef, comb jellies floating in the open ocean and sea otters playing along a rocky shore.
SPACE
Franklin Institute
Philadelphia
Opens: Fall 2023

To design this new two-story gallery dedicated to the future of space exploration, exhibit planners met with local students and teachers to find out what they wanted to learn. The result is an experience that, among other things, will showcase the current and future technologies needed to live and work in space as well as the many career paths into the aerospace industry.
Bird House
Smithsonian’s National Zoo
Washington, D.C.
Opens: To be announced

With a focus on bird migration and conservation in the Americas, the zoo’s new bird house will feature three aviaries: The first will show how the Delaware Bay is a key refueling spot for migratory shorebirds, the second will demonstrate how seasonal wetlands in the Midwest serve waterfowl and the third will illustrate how a tropical coffee farm can provide respite for songbirds in winter.
Robot & AI Museum
Seoul, South Korea
Opens: To be announced

Though details are still scant, this museum dedicated to furthering public knowledge of robotics, artificial intelligence and machine learning is expected to open later this year.

A mysterious new disease may be to blame for severe, unexplained inflammation in older men. Now, researchers have their first good look at who the disease strikes, and how often.

VEXAS syndrome, an illness discovered just two years ago, affects nearly 1 in 4,000 men over 50 years old, scientists estimate January 24 in JAMA. The disease also occurs in older women, though less frequently. Altogether, more than 15,000 people in the United States may be suffering from the syndrome, says study coauthor David Beck, a clinical geneticist at NYU Langone Health in New York City. Those numbers indicate that physicians should be on the lookout for VEXAS, Beck says. “It’s underrecognized and underdiagnosed. A lot of physicians aren’t yet aware of it.”
Beck’s team reported discovering VEXAS syndrome in 2020, linking mutations in a gene called UBA1 to a suite of symptoms including fever, low blood cell count and inflammation. His team’s new study is the first to estimate how often VEXAS occurs in the general population — and the results are surprising. “It’s more prevalent than we suspected,” says Emma Groarke, a hematologist at the National Institutes of Health in Bethesda, Md., who was not involved with the study.
VEXAS tends to show up later in life ­­— after people somehow acquire UBA1 mutations in their blood cells. Patients may feel overwhelming fatigue, lethargy and have skin rashes, Beck says. “The disease is progressive, and it’s severe.” VEXAS can also be deadly. Once a person’s symptoms begin, the median survival time is about 10 years, his team has found.

Until late 2020, no one knew that there was a genetic thread connecting VEXAS syndrome’s otherwise unexplained symptoms. In fact, individuals may be diagnosed with other conditions, including polyarteritis nodosa, an inflammatory blood disease, and relapsing polychondritis, a connective tissue disorder, before being diagnosed with VEXAS.

To ballpark the number of VEXAS-affected individuals, Beck’s team combed through electronic health records of more than 160,000 people in Pennsylvania, in a collaboration with the NIH and Geisinger Health. In people over 50, the disease-causing UBA1 mutations showed up in roughly 1 in 4,000 men. Among women in that age bracket, about 1 in 26,000 had the mutations.

A genetic test of the blood can help doctors diagnose VEXAS, and treatments like steroids and other immunosuppressive drugs, which tamp down inflammation, can ease symptoms. Groarke and her NIH colleagues have also started a small phase II clinical trial testing bone marrow transplants as a way to swap patients’ diseased blood cells for healthy ones.

Beck says he hopes to raise awareness about the disease, though he recognizes that there’s much more work to do. In his team’s study, for instance, the vast majority of participants were white Pennsylvanians, so scientists don’t know how the disease affects other populations. Researchers also don’t know what spurs the blood cell mutations, nor how they spark an inflammatory frenzy in the body.

“The more patients that are diagnosed, the more we’ll learn about the disease,” Beck says. “This is just one step in the process of finding more effective therapies.”

For nearly 650 years, the fortress walls in the Chinese city of Xi’an have served as a formidable barrier around the central city. At 12 meters high and up to 18 meters thick, they are impervious to almost everything — except subatomic particles called muons.

Now, thanks to their penetrating abilities, muons may be key to ensuring that the walls that once protected the treasures of the first Ming Dynasty — and are now a national architectural treasure in their own right — stand for centuries more.

A refined detection method has provided the highest-resolution muon scans yet produced of any archaeological structure, researchers report in the Jan. 7 Journal of Applied Physics. The scans revealed interior density fluctuations as small as a meter across inside one section of the Xi’an ramparts. The fluctuations could be signs of dangerous flaws or “hidden structures archaeologically interesting for discovery and investigation,” says nuclear physicist Zhiyi Liu of Lanzhou University in China.
Muons are like electrons, only heavier. They rain down all over the planet, produced when charged particles called cosmic rays hit the atmosphere. Although muons can travel deep into earth and stone, they are scattered or absorbed depending on the material they encounter. Counting the ones that pass through makes them useful for studying volcano interiors, scanning pyramids for hidden chambers and even searching for contraband stashed in containers impervious to X-rays (SN: 4/22/22).

Though muons stream down continuously, their numbers are small enough that the researchers had to deploy six detectors for a week at a time to collect enough data for 3-D scans of the rampart.

It’s now up to conservationists to determine how to address any density fluctuations that might indicate dangerous flaws, or historical surprises, inside the Xi’an walls.

High-tech shrink art may be the key to making tiny electronics, 3-D nanostructures or even holograms for hiding secret messages.

A new approach to making tiny structures relies on shrinking them down after building them, rather than making them small to begin with, researchers report in the Dec. 23 Science.

The key is spongelike hydrogel materials that expand or contract in response to surrounding chemicals (SN: 1/20/10). By inscribing patterns in hydrogels with a laser and then shrinking the gels down to about one-thirteenth their original size, the researchers created patterns with details as small as 25 billionths of a meter across.
At that level of precision, the researchers could create letters small enough to easily write this entire article along the circumference of a typical human hair.

Biological scientist Yongxin Zhao and colleagues deposited a variety of materials in the patterns to create nanoscopic images of Chinese zodiac animals. By shrinking the hydrogels after laser etching, several of the images ended up roughly the size of a red blood cell. They included a monkey made of silver, a gold-silver alloy pig, a titanium dioxide snake, an iron oxide dog and a rabbit made of luminescent nanoparticles.
Because the hydrogels can be repeatedly shrunk and expanded with chemical baths, the researchers were also able to create holograms in layers inside a chunk of hydrogel to encode secret information. Shrinking a hydrogel hologram makes it unreadable. “If you want to read it, you have to expand the sample,” says Zhao, of Carnegie Mellon University in Pittsburgh. “But you need to expand it to exactly the same extent” as the original. In effect, knowing how much to expand the hydrogel serves as a key to unlock the information hidden inside.

But the most exciting aspect of the research, Zhao says, is the wide range of materials that researchers can use on such minute scales. “We will be able to combine different types of materials together and make truly functional nanodevices.”

A type of bacteria that’s overabundant in the nasal passages of people with hay fever may worsen symptoms. Targeting that bacteria may provide a way to rein in ever-running noses.

Hay fever occurs when allergens, such as pollen or mold, trigger an inflammatory reaction in the nasal passages, leading to itchiness, sneezing and overflowing mucus. Researchers analyzed the composition of the microbial population in the noses of 55 people who have hay fever and those of 105 people who don’t. There was less diversity in the nasal microbiome of people who have hay fever and a whole lot more of a bacterial species called Streptococcus salivarius, the team reports online January 12 in Nature Microbiology.
S. salivarius was 17 times more abundant in the noses of allergy sufferers than the noses of those without allergies, says Michael Otto, a molecular microbiologist at the National Institute of Allergy and Infectious Diseases in Bethesda, Md. That imbalance appears to play a part in further provoking allergy symptoms. In laboratory experiments with allergen-exposed cells that line the airways, S. salivarius boosted the cells’ production of proteins that promote inflammation.

And it turns out that S. salivarius really likes runny noses. One prominent, unpleasant symptom of hay fever is the overproduction of nasal discharge. The researchers found that S. salivarius binds very well to airway-lining cells exposed to an allergen and slathered in mucus — better than a comparison bacteria that also resides in the nose.

The close contact appears to be what makes the difference. It means that substances on S. salivarius’ surface that can drive inflammation — common among many bacteria — are close enough to exert their effect on cells, Otto says.

Hay fever, which disrupts daily activities and disturbs sleep, is estimated to affect as many as 30 percent of adults in the United States. The new research opens the door “to future studies targeting this bacteria” as a potential treatment for hay fever, says Mahboobeh Mahdavinia, a physician scientist who studies immunology and allergies at Rush University Medical Center in Chicago.

But any treatment would need to avoid harming the “good” bacteria that live in the nose, says Mahdavinia, who was not involved in the research.

The proteins on S. salivarius’ surface that are important to its ability to attach to mucus-covered cells might provide a target, says Otto. The bacteria bind to proteins called mucins found in the slimy, runny mucus. By learning more about S. salivarius’ surface proteins, Otto says, it may be possible to come up with “specific methods to block that adhesion.”

Today’s red jungle fowl — the wild forebears of the domesticated chicken — are becoming more chickenlike. New research suggests that a large proportion of the wild fowl’s DNA has been inherited from chickens, and relatively recently.

Ongoing interbreeding between the two birds may threaten wild jungle fowl populations’ future, and even hobble humans’ ability to breed better chickens, researchers report January 19 in PLOS Genetics.

Red jungle fowl (Gallus gallus) are forest birds native to Southeast Asia and parts of South Asia. Thousands of years ago, humans domesticated the fowl, possibly in the region’s rice fields (SN: 6/6/22).
“Chickens are arguably the most important domestic animal on Earth,” says Frank Rheindt, an evolutionary biologist at the National University of Singapore. He points to their global ubiquity and abundance. Chicken is also one of the cheapest sources of animal protein that humans have.

Domesticated chickens (G. gallus domesticus) were known to be interbreeding with jungle fowl near human settlements in Southeast Asia. Given the unknown impacts on jungle fowl and the importance of chickens to humankind, Rheindt and his team wanted to gather more details. Wild jungle fowl contain a store of genetic diversity that could serve as a crucial resource for breeding chickens resistant to diseases or other threats.

The researchers analyzed and compared the genomes — the full complement of an organism’s DNA — of 63 jungle fowl and 51 chickens from across Southeast Asia. Some of the jungle fowl samples came from museum specimens collected from 1874 through 1939, letting the team see how the genetic makeup of jungle fowl has changed over time.

Over the last century or so, wild jungle fowl’s genomes have become increasingly similar to chickens’. Between about 20 and 50 percent of the genomes of modern jungle fowl originated in chickens, the team found. In contrast, many of the roughly 100-year-old jungle fowl had a chicken-ancestry share in the range of a few percent.

The rapid change probably comes from human communities expanding into the region’s wilderness, Rheindt says. Most modern jungle fowl live in close vicinity to humans’ free-ranging chickens, with which they frequently interbreed.

Such interbreeding has become “almost the norm now” for any globally domesticated species, Rheindt says, such as dogs hybridizing with wolves and house cats crossing with wildcats. Pigs, meanwhile, are mixing with wild boars and ferrets with polecats.
Wild populations that interbreed with their domesticated counterparts could pick up physical or behavioral traits that change how the hybrids function in their ecosystem, says Claudio Quilodrán, a conservation geneticist at the University of Geneva not involved with this research.

The effect is likely to be negative, Quilodrán says, since some of the traits coming into the wild population have been honed for human uses, not for survival in the local environment.

Wild jungle fowl have lost their genetic diversity as they’ve interbred too. The birds’ heterozygosity — a measure of a population’s genetic diversity — is now just a tenth of what it was a century ago.

“This result is initially counterintuitive,” Rheindt says. “If you mix one population with another, you would generally expect a higher genetic diversity.”

But domesticated chickens have such low genetic diversity that certain versions of jungle fowl genes are being swept out of the population by a tsunami of genetic homogeneity. The whittling down of these animals’ genetic toolkit may leave them vulnerable to conservation threats.

“Having lots of genetic diversity within a species increases the chance that certain individuals contain the genetic background to adapt to a varied range of different environmental changes and diseases,” says Graham Etherington, a computational biologist at the Earlham Institute in Norwich, England, who was not involved with this research.

A shallower jungle fowl gene pool could also mean diminished resources for breeding better chickens. The genetics of wild relatives are sometimes used to bolster the disease or pest resistance of domesticated crop plants. Jungle fowl genomes could be similarly valuable for this reason.

“If this trend continues unabated, future human generations may only be able to access the entirety of ancestral genetic diversity of chickens in the form of museum specimens,” Rheindt says, which could hamper chicken breeding efforts using the wild fowl genes.

Some countries such as Singapore, Rheindt says, have started managing jungle fowl populations to reduce interbreeding with chickens.

A 120-million-year-old fossil bird found in China could offer some new clues about how landbound dinosaurs evolved into today’s flying birds. The dove-sized Cratonavis zhui sported a dinosaur-like head atop a body similar to those of today’s birds, researchers report in the January Nature Ecology & Evolution.

The flattened specimen came from the Jiufotang Formation, an ancient body of rock in northeastern China that is a hotbed for preserved feathered dinosaurs and archaic birds. CT scans revealed that Cratonavis had a skull that was nearly identical (albeit smaller) as those of theropod dinosaurs like Tyrannosaurus rex, paleontologist Li Zhiheng of the Chinese Academy of Sciences in Beijing and colleagues report. This means that Cratonavis still hadn’t evolved the mobile upper jaw found in modern birds (SN: 5/2/18).
It’s among just a handful of specimens that belong to a recently identified group of intermediate birds known as the jinguofortisids, says Luis Chiappe, a paleontologist at the Natural History Museum of Los Angeles County who was not involved in the study. Its dino-bird mishmash “is not unexpected.” Most birds discovered from the Age of Dinosaurs exhibited more primitive, toothed heads than today’s birds, he says. But the new find “builds on our understanding of this primitive group of birds that are at the base of the tree of birds.”

Cratonavis also had an unusually elongated scapula and hallux, or backward-facing toe. Rarely seen in Cretaceous birds, enlarged shoulder blades might have compensated for the bird’s otherwise underwhelming flight mechanics, the researchers say. And that hefty big toe? It bucks the trend of shrinking metatarsals seen as birds continued to evolve. Cratonavis might have used this impressive digit to hunt like today’s birds of prey, Li’s team says.

Filling those shoes may have been too big of a job for Cratonavis, though. Given its size, Chiappe says, the dino-headed bird would have most likely been a petite hunter, taking down the likes of beetles, grasshoppers and the occasional lizard rather than terrorizing the skies.

SEATTLE — Luke Skywalker’s home planet in Star Wars is the stuff of science fiction. But Tatooine-like planets in orbit around pairs of stars might be our best bet in the search for habitable planets beyond our solar system.

Many stars in the universe come in pairs. And lots of those should have planets orbiting them (SN: 10/25/21). That means there could be many more planets orbiting around binaries than around solitary stars like ours. But until now, no one had a clear idea about whether those planets’ environments could be conducive to life. New computer simulations suggest that, in many cases, life could imitate art.
Earthlike planets orbiting some configurations of binary stars can stay in stable orbits for at least a billion years, researchers reported January 11 at the American Astronomical Society meeting. That sort of stability, the researchers propose, would be enough to potentially allow life to develop, provided the planets aren’t too hot or cold.

Of the planets that stuck around, about 15 percent stayed in their habitable zone — a temperate region around their stars where water could stay liquid — most or even all of the time.

The researchers ran simulations of 4,000 configurations of binary stars, each with an Earthlike planet in orbit around them. The team varied things like the relative masses of the stars, the sizes and shapes of the stars’ orbits around each other, and the size of the planet’s orbit around the binary pair.

The scientists then tracked the motion of the planets for up to a billion years of simulated time to see if the planets would stay in orbit over the sorts of timescales that might allow life to emerge.

A planet orbiting binary stars can get kicked out of the star system due to complicated interactions between the planet and stars. In the new study, the researchers found that, for planets with large orbits around star pairs, only about 1 out of 8 were kicked out of the system. The rest were stable enough to continue to orbit for the full billion years. About 1 in 10 settled in their habitable zones and stayed there.

Of the 4,000 planets that the team simulated, roughly 500 maintained stable orbits that kept them in their habitable zones at least 80 percent of the time.

“The habitable zone . . . as I’ve characterized it so far, spans from freezing to boiling,” said Michael Pedowitz, an undergraduate student at the College of New Jersey in Ewing who presented the research. Their definition is overly strict, he said, because they chose to model Earthlike planets without atmospheres or oceans. That’s simpler to simulate, but it also allows temperatures to fluctuate wildly on a planet as it orbits.
“An atmosphere and oceans would smooth over temperature variations fairly well,” says study coauthor Mariah MacDonald, an astrobiologist also at the College of New Jersey. An abundance of air and water would potentially allow a planet to maintain habitable conditions, even if it spent more of its time outside of the nominal habitable zone around a binary star system.

The number of potentially habitable planets “will increase once we add atmospheres,” MacDonald says, “but I can’t yet say by how much.”

She and Pedowitz hope to build more sophisticated models in the coming months, as well as extend their simulations beyond a billion years and include changes in the stars that can affect conditions in a solar system as it ages.

The possibility of stable and habitable planets in binary star systems is a timely issue says Penn State astrophysicist Jason Wright, who was not involved in the study.

“At the time Star Wars came out,” he says, “we didn’t know of any planets outside the solar system, and wouldn’t for 15 years. Now we know that there are many and that they orbit these binary stars.”

These simulations of planets orbiting binaries could serve as a guide for future experiments, Wright says. “This is an under-explored population of planets. There’s no reason we can’t go after them, and studies like this are presumably showing us that it’s worthwhile to try.”