Enlarge / Artist's conception of a dark matter filament containing a galaxy with large jets. (Caltech noted that some details of this image were created using AI.) (credit: Martijn Oei (Caltech) / Dylan Nelson (IllustrisTNG Collaboration).)

The supermassive black holes that sit at the center of galaxies aren't just decorative. The intense radiation they emit when feeding helps drive away gas and dust that would otherwise form stars, providing feedback that limits the growth of the galaxy. But their influence may extend beyond the galaxy they inhabit. Many black holes produce jets and, in the case of supermassive versions, these jets can eject material entirely out of the galaxy.

Now, researchers are getting a clearer picture of just how far outside of the galaxy their influence can reach. A new study describes the largest-ever jets observed, extending across a total distance of 23 million light-years (seven megaparsecs). At those distances, the jets could easily send material into other galaxies and across the cosmic web of dark matter that structures the Universe.

Extreme jets

Jets are formed in the complex environment near a black hole. The intense heating of infalling material ionizes and heats it, creating electromagnetic fields that act as a natural particle accelerator. This creates jets of particles that travel at a substantial fraction of the speed of light. These will ultimately slam into nearby material, creating shockwaves that heat and accelerate that, too. Over time, this leads to large-scale, coordinated outflows of material, with the scale of the jet being proportional to a combination of the size of the black hole and the amount of material it is feeding on.

Enlarge / The Kalalau Valley between sheer cliffs in the Na Pali Coast State Park on the western shore of the island of Kauai in Hawaii, United States. This view is from the Pihea Trail in the Kokee State Park. (credit: Getty | Jon G. Fuller)

The Hawaiian island of Kauai may not have any spewing lava, but hikers along the magnificent Napali coast have brought their own volcanic action recently, violently hollowing their innards amid the gushing waterfalls and deeply carved valleys.

Between August and early September, at least 50 hikers fell ill with norovirus along the famed Kalalau Trail, which has been closed since September 4 for a deep cleaning. The rugged 11-mile trail runs along the northwest coast of the island, giving adventurers breathtaking views of stunning sea cliffs and Kauai's lush valleys. It's situated just north of Waimea Canyon State Park, also known as the Grand Canyon of the Pacific.

"It’s one of the most beautiful places in the world. I feel really fortunate to be able to be there, and appreciate and respect that land,” one hiker who fell ill in late August told The Washington Post. "My guts exploding all over that land was not what I wanted to do at all."

Enlarge / Rendering of an individual crew quarter within the Axiom habitat module. (credit: Axiom Space)

Axiom Space is facing significant financial headwinds as the company attempts to deliver on two key commercial programs for NASA—the development of a private space station in low-Earth orbit and spacesuits that could one day be worn by astronauts on the Moon.

Forbes reports that Axiom Space, which was founded by billionaire Kam Ghaffarian and NASA executive Mike Suffredini in 2016, has been struggling to raise money to keep its doors open and has had difficulties meeting its payroll dating back to at least early 2023. In addition, the Houston-based company has fallen behind on payments to key suppliers, including Thales Alenia Space for its space station and SpaceX for crewed launches.

"The lack of fresh capital has exacerbated long-standing financial challenges that have grown alongside Axiom’s payroll, which earlier this year was nearly 1,000 employees," the publication reports. "Sources familiar with the company’s operations told Forbes that co-founder and CEO Michael Suffredini, who spent 30 years at NASA, ran Axiom like a big government program instead of the resource-constrained startup it really was. His mandate to staff up to 800 workers by the end of 2022 led to mass hiring so detached from product development needs that new engineers often found themselves with nothing to do."

Enlarge / Many have seen a reflection of Vincent van Gogh's inner turmoil in the swirling vortices of The Starry Night. (credit: Public doman)

Vincent van Gogh's most famous painting is The Starry Night (1889), created (along with several other masterpieces) during the artist's stay at an asylum in Arles following his breakdown in December 1888. Where some have seen the swirling vortices of the night sky depicted in Starry Night as a reflection of van Gogh's own inner turmoil, physicists often see a masterful depiction of atmospheric turbulence. According to a new paper published in the journal Physics of Fluids, the illusion of movement in van Gogh's blue sky is also due to the scale of the paint strokes—a second kind of "hidden turbulence" at the microscale that diffuses throughout the entire canvas.

“It reveals a deep and intuitive understanding of natural phenomena,” said co-author Yongxiang Huang of Xiamen University in China. “Van Gogh’s precise representation of turbulence might be from studying the movement of clouds and the atmosphere or an innate sense of how to capture the dynamism of the sky.”

Physicists have long been fascinated by van Gogh's innate feel for turbulence. As previously reported, in a 2014 TED-Ed talk, Natalya St. Clair, a research associate at the Concord Consortium and coauthor of The Art of Mental Calculation, used Starry Night to illuminate the concept of turbulence in a flowing fluid. In particular, she talked about how van Gogh's technique allowed him (and other Impressionist painters) to represent the movement of light across water or in the twinkling of stars. We see this as a kind of shimmering effect, because the eye is more sensitive to changes in the intensity of light (a property called luminance) than to changes in color.

Enlarge / Portion of a reproduction of cave paintings in France, showing rhinos (among other species). (credit: JEFF PACHOUD)

For most people, an extinct species is an abstraction, a set of bones they might have seen on display in a museum. For Gennady Boeskorov, they are things he has interacted with directly, studying their fur, their skin, their internal organs—experiencing these animals much as they existed thousands of years ago. Some of the well-preserved Pleistocene animals he has worked with include the mummified remains of woolly mammoths (Mammuthus primigenius), an extinct form of rabbit (Lepus tanaiticus), and cave lion cubs (Panthera spelaea).

His latest paper also makes it clear that woolly rhinoceroses belong on this list. Boeskorov is a senior researcher at the Diamond and Precious Metals Geology Institute, Siberian Branch of the Russian Academy of Sciences, as well as a professor at the North-Eastern Federal University in Yakutsk. This July, he and his colleagues described the relatively recent discovery of three woolly rhinoceros mummies, one of which is new to science, in a paper published in the journal Doklady Earth Sciences.

Woolly rhinos (Coelodonta antiquitatis) were stocky, long-haired, two-horned denizens that inhabited Eurasia during the Pleistocene, a period that includes the most recent glacial expansion. They coexisted with woolly mammoths, placing second on the list of largest animals in this ecosystem (behind their tusked proboscidean coevals), and shared a similar dense coat of hair to protect against the cold.

Enlarge / The Windy Fire blazes through the Long Meadow Grove of giant sequoia trees near The Trail of 100 Giants overnight in Sequoia National Forest on September 21, 2021, near California Hot Springs, California. (credit: David McNew/Getty Images)

Space is more accessible than ever thanks to the proliferation of small satellites and more affordable launch prices, which opened the door to bespoke applications like global pollution monitoring, crop observations, and new ways of collecting weather and climate data.

Now you can add wildfire detection to the list. Satellites have observed wildfires from space for decades, but a new initiative partially funded by Google's philanthropic arm aims to deploy more than 50 small satellites in low-Earth orbit to pinpoint flare-ups as small as a classroom anywhere in the world.

The FireSat constellation, managed by a nonprofit called Earth Fire Alliance (EFA), will be the first satellite fleet dedicated to detecting and tracking wildfires. Google announced a fresh investment of $13 million in the FireSat constellation Monday, building on the tech giant's previous contributions to support the development of custom infrared sensors for the FireSat satellites.

Enlarge / The Fifty-Eight holes board from Çapmalı. (credit: W. Crist et al., 2024)

An ancient board game known as Hounds and Jackals has long been believed to have originated in Egypt. However, according to a paper published in the European Journal of Archaeology, a version of the game board found in present-day Azerbaijan might date back even earlier, suggesting that the game originated in Asia.

As previously reported, there is archaeological evidence for various kinds of board games from all over the world dating back millennia: Senet and Mehen in ancient Egypt, for example, or a strategy game called ludus latrunculorum ("game of mercenaries") favored by Roman legions. A 4,000-year-old board discovered last year at an archaeological site in Oman's Qumayrah Valley might be a precursor to an ancient Middle Eastern game known as the Royal Game of Ur (or the Game of Twenty Squares), a two-player game that may have been one of the precursors to backgammon (or was replaced in popularity by backgammon). Like backgammon, it's essentially a race game in which players compete to see who can move all their pieces along the board before their opponent.

Last year, archaeologists discovered a 500-year-old game board in the ruins of Ćmielów Castle in Poland. It was a two-person strategy board game called Mill, also known as Nine Men's Morris, Merels, or "cowboy checkers" in North America. The earliest-known Mill game board was found carved into the roofing slabs of an Egyptian temple at Kurna, which likely predates the Common Era. Historians believe it was well-known to the Romans, who may have learned of the game through trade routes.

Enlarge / A recall notice is posted next to Boar's Head meats that are displayed at a Safeway store on July 31, 2024, in San Rafael, California. (credit: Getty | Justin Sullivan)

The Boar's Head deli-meat plant at the epicenter of a nationwide Listeria outbreak that killed nine people so far harbored the deadly germ in a common area of the facility deemed "low risk" for Listeria. Further, it had no written plans to prevent cross-contamination of the dangerous bacteria to other products and areas. That's according to a federal document newly released by Boar's Head.

On Friday, the company announced that it is indefinitely closing that Jarratt, Virginia-based plant and will never again produce liverwurst—the product that Maryland health investigators first identified as the source of the outbreak strain of Listeria monocytogenes. The finding led to the recall of more than 7 million pounds of Boar's Head meat. The Jarratt plant, where the company's liverwurst is made, has been shuttered since late July amid the investigation into how the outbreak occurred.

In the September 13 update, Boar's Head explained that "our investigation has identified the root cause of the contamination as a specific production process that only existed at the Jarratt facility and was used only for liverwurst. With this discovery, we have decided to permanently discontinue liverwurst."

Enlarge / Zihao Ou, who helped develop this solution, holds a tube of it.

One key challenge in medical imaging is to look past skin and other tissue that are opaque to see internal organs and structures. This is the reason we need things like ultrasonography, magnetic resonance, or X-rays. There are chemical clearing agents that can make tissue transparent, like acrylamide or tetrahydrofuran, but they are almost never used in living organisms because they’re either highly toxic or can dissolve away essential biomolecules.

But now, a team of Stanford University scientists has finally found an agent that can reversibly make skin transparent without damaging it. This agent was tartrazine, a popular yellow-orange food dye called FD&C Yellow 5 that is notably used for coloring Doritos.

Playing with light

We can’t see through the skin because it is a complex tissue comprising aqueous-based components such as cell interiors and other fluids, as well as protein and lipids. The refractive index is a value that indicates how much light slows down (on average, of course) while going through a material compared to going through a vacuum. The refractive index of those aqueous components is low, while the refractive index of the proteins and lipids is high. As a result, light traveling through skin constantly bends as it endlessly crosses the boundary between high and low refractive index materials.

Enlarge (credit: Jason Edwards via Getty)

Earthquake scientists detected an unusual signal on monitoring stations used to detect seismic activity during September 2023. We saw it on sensors everywhere, from the Arctic to Antarctica.

We were baffled—the signal was unlike any previously recorded. Instead of the frequency-rich rumble typical of earthquakes, this was a monotonous hum, containing only a single vibration frequency. Even more puzzling was that the signal kept going for nine days.

Initially classified as a “USO”—an unidentified seismic object—the source of the signal was eventually traced back to a massive landslide in Greenland’s remote Dickson Fjord. A staggering volume of rock and ice, enough to fill 10,000 Olympic-sized swimming pools, plunged into the fjord, triggering a 200-meter-high mega-tsunami and a phenomenon known as a seiche: a wave in the icy fjord that continued to slosh back and forth, some 10,000 times over nine days.

Enlarge (credit: Hal Beral)

For many creatures, having a limb caught in a predator’s mouth is usually a death sentence. Not starfish, though—they can detach the limb and leave the predator something to chew on while they crawl away. But how can they pull this off?

Starfish and some other animals (including lizards and salamanders) are capable of autonomy (shedding a limb when attacked). The biology behind this phenomenon in starfish was largely unknown until now. An international team of researchers led by Maurice Elphick, professor of Animal Physiology and Neuroscience at Queen Mary University of London, have found that a neurohormone released by starfish is largely responsible for detaching limbs that end up in a predator’s jaws.

So how does this neurohormone (specifically a neuropeptide) let the starfish get away? When a starfish is under stress from a predatory attack, this hormone is secreted, stimulating a muscle at the base of the animal’s arm that allows the arm to break off.