It rains on the Sun, and scientists at the University of Hawaiʻi Institute for Astronomy (IfA) have finally uncovered the reason why.

Unlike the water droplets that fall on Earth, solar rain occurs within the Sun’s corona, a region of extremely hot plasma that extends above its surface. This phenomenon involves cooler, denser clumps of plasma that condense high in the corona and then descend back toward the Sun. For years, researchers struggled to understand how this process could happen so rapidly during solar flares.

New explanation
Now, that long-standing mystery has been solved by Luke Benavitz, a first-year graduate student at IfA, and astronomer Jeffrey Reep. Their findings, published in the Astrophysical Journal, provide an essential update to solar models that have puzzled scientists for decades.

“At present, models assume that the distribution of various elements in the corona is constant throughout space and time, which clearly isn’t the case,” said Benavitz. “It’s exciting to see that when we allow elements like iron to change with time, the models finally match what we actually observe on the Sun. It makes the physics come alive in a way that feels real.”

Why it matters
The new finding means solar scientists can better model how the Sun behaves during flares, insights that could one day help predict space weather that affects our daily lives.

Earlier models required heating over hours or days to explain coronal rain; however, solar flares can happen in just minutes. The IfA team’s work shows that shifting elemental abundances can explain how rain can quickly form.

“This discovery matters because it helps us understand how the Sun really works,” said Reep. “We can’t directly see the heating process, so we use cooling as a proxy. But if our models haven’t treated abundances properly, the cooling time has likely been overestimated. We might need to go back to the drawing board on coronal heating, so there’s a lot of new and exciting work to be done.”

For millions of years, a fragment of ice and dust drifted between the stars—like a sealed bottle cast into the cosmic ocean. This summer, that bottle finally washed ashore in our solar system and was designated 3I/ATLAS, only the third known interstellar comet. When Auburn University scientists pointed NASA's Neil Gehrels Swift Observatory toward it, they made a remarkable find: the first detection of hydroxyl (OH) gas from this object, a chemical fingerprint of water.

Swift's space-based telescope could spot the faint ultraviolet glow that ground observatories can't see—because, high above Earth's atmosphere, it captures light that never reaches Earth's surface.

Detecting water—through its ultraviolet by-product, hydroxyl—is a major breakthrough for understanding how interstellar comets evolve. In solar-system comets, water is the yardstick by which scientists measure their overall activity and track how sunlight drives the release of other gases. It's the chemical benchmark that anchors every comparison of volatile ices in a comet's nucleus.

Finding the same signal in an interstellar object means that, for the first time, astronomers can begin to place 3I/ATLAS on the same scale used to study native solar-system comets—a step toward comparing the chemistry of planetary systems across the galaxy.

What makes 3I/ATLAS remarkable is where this water activity occurs. The Swift observations detected OH when the comet was nearly three times farther from the sun than Earth—well beyond the region where water ice on a comet's surface can easily sublimate—and measured a water-loss rate of about 40 kilograms per second—roughly the output of a fire hose running at full blast.

At those distances, most solar-system comets remain quiet. The strong ultraviolet signal from ATLAS suggests that something else is at work: perhaps sunlight is heating small icy grains released from the nucleus, allowing them to vaporize and feed the surrounding cloud of gas. Such extended sources of water have been seen only in a handful of distant comets and point to complex, layered ices that preserve clues to how these objects formed.

Africa's Great Green Wall project began as an ambitious plan to build a 15-kilometer-wide band of trees across the north of Africa. The African Union launched the project in 2007 with plans for the trees to extend for 6,000 kilometers through 11 countries in the Sahel, restoring 100 million hectares of land from Senegal to Djibouti and Ethiopia. Its main aim was to prevent the Sahara Desert from advancing. But the Great Green Wall's also been billed as a solution to climate change, poverty, and even extremism.

Senegal has been one of the most active countries implementing the Great Green Wall initiative, despite being among the smallest. It has targeted 817,500 hectares of land for restoration. Environmental researchers Annah Lake Zhu and Amadou Ndiaye were part of a team who looked at satellite images of some of Senegal's section of the wall and found that only one out of 36 planted areas analyzed was more green than it would have been naturally. The project is not an actual wall of trees but rather a mosaic of rehabilitated land. But increased greenery should still be visible from satellite imagery. They also found that financial pledges were often left unmet, money for the wall didn't make it to ground level and new trees had low survival rates.

Two spacecraft on Mars have captured new images of the interstellar comet 3I/ATLAS in the closest view that the European Space Agency (ESA) will get of the mysterious object, according to an ESA statement.

The comet, which came from an unknown star system far beyond our own, is currently taking a months-long tour of the inner solar system. It made its closest approach to Mars Friday (Oct. 3) ahead of a close encounter with the sun on Oct. 30. During its recent flyby of the Red Planet, the comet came within view of ESA and NASA's fleet of robotic explorers, including ESA's ExoMars Trace Gas Orbiter (TGO) and Mars Express orbiter.

Soaring 18.6 million miles (30 million kilometers) overhead, the comet proved too dim for Mars Express to capture. However, the ExoMars TGO satellite succeeded in snapping a series of images, which ESA combined into an animated GIF. The animation shows the comet — visible as a fuzzy, bright dot — descending toward the center of the frame as it zooms away from Mars at an estimated 130,000 mph (210,000 km/h).

Scientists have recently developed a powerful new approach to fighting cancer using specially engineered immune cells called CAR-NK (natural killer) cells. These cells function much like CAR-T cells, which can be customized to seek out and destroy cancer, but rely on a different type of immune cell as their foundation.

Researchers at MIT and Harvard Medical School have now designed an improved version of CAR-NK cells that are far less likely to be attacked by a patient’s own immune system, a major obstacle in current cell-based therapies.

This breakthrough could also open the door to “off-the-shelf” CAR-NK treatments that doctors can administer immediately after diagnosis, eliminating the long preparation period required for most personalized cancer immunotherapies. Conventional CAR-NK and CAR-T cell production often takes several weeks.

Safer, Stronger Cancer Killers
“This enables us to do one-step engineering of CAR-NK cells that can avoid rejection by host T cells and other immune cells. And, they kill cancer cells better and they’re safer,” says Jianzhu Chen, an MIT professor of biology, a member of the Koch Institute for Integrative Cancer Research, and one of the senior authors of the study.

When tested in mice with human-like immune systems, the newly engineered cells successfully eliminated most cancer cells while avoiding detection and destruction by the host immune system.

The Hawaiian honeycreeper digs for bugs, using its lower beak like a pickaxe to chip into wood.

The European Space Agency’s (ESA) Mars Express and ExoMars Trace Gas Orbiter are excellent spacecraft that have provided insights into the Red Planet time and time again. They are also capable of doing things beyond their standard job. They recently looked at interstellar comet 3I/ATLAS. They were also used to measure the winds on the surface of Mars, something that neither orbiter was designed to do.

The incredible results were possible thanks to an extensive catalog of dust devils, tornadoes of dust that have been seen by several rovers and orbiters in recent years. The combined data of the two ESA orbiters culminated in a large catalog of events, 1,039 in total, providing a new understanding of wind speed on Mars. The work showed that dust devils and winds can reach speeds of up to 160 kilometers (100 miles) per hour. They are much faster than previously assumed.

Using cutting-edge simulations, scientists at Goethe University Frankfurt revealed that not just magnetic fields, but a process called magnetic reconnection, helps extract energy from a spinning black hole to launch jets of matter stretching thousands of light-years. These immense cosmic beams, moving at nearly light speed, scatter energy and matter across galaxies, shaping their evolution.

From a “Nebula Without Stars” to a Giant Galaxy
For nearly 200 years, astronomers were uncertain about the true nature of the bright object in the constellation Virgo that Charles Messier recorded in 1784 as “87: Nebula without stars.” What appeared to be a fuzzy patch of light was later revealed to be an enormous galaxy. When a mysterious jet of light was spotted coming from its center in 1918, scientists had no idea what could be producing it.

At the core of this massive galaxy, now known as M87, lies the supermassive black hole M87*, containing about six and a half billion times the mass of the Sun. This black hole spins rapidly, and its rotation powers a stream of charged particles that shoots out at nearly the speed of light, stretching some 5,000 light-years into space. Similar jets are seen around other rotating black holes, helping to scatter energy and matter throughout the universe and shape the growth of galaxies.

Cracking the Code of Black Hole Power
A research team from Goethe University Frankfurt, led by Prof. Luciano Rezzolla, has developed a new computational tool called the Frankfurt particle-in-cell code for black hole spacetimes (FPIC). This simulation code precisely models how a spinning black hole transforms its rotational energy into a powerful jet. The researchers discovered that, in addition to the well-known Blandford–Znajek mechanism, long thought to explain how black holes extract rotational energy through magnetic fields, another key process also plays a role: magnetic reconnection. In this phenomenon, magnetic field lines snap and reconnect, converting magnetic energy into heat, radiation, and bursts of plasma.

Using the FPIC code, the team simulated the behavior of countless charged particles and extreme electromagnetic fields influenced by the intense gravity surrounding the black hole. Dr. Claudio Meringolo, the main developer of the code, explained, “Simulating such processes is crucial for understanding the complex dynamics of relativistic plasmas in curved spacetimes near compact objects, which are governed by the interplay of extreme gravitational and magnetic fields.”

Running these simulations required extraordinary computing resources, totaling millions of CPU hours on Frankfurt’s “Goethe” supercomputer and Stuttgart’s “Hawk.” Such immense processing power was needed to solve Maxwell’s equations and the equations of motion for electrons and positrons within the framework of Albert Einstein’s general theory of relativity.

An asteroid recently made the second closest pass to Earth ever observed on October 1st. And astronomers only found it after it had already completed its closest approach. That offers another lesson in how difficult it is to find small objects coming close to our planet in the vast dark ocean of space.

To be clear, the asteroid, now known as Asteroid 2025 TF, didn’t pose any sort of danger. It is likely only 1-3m across, and would have created a pretty spectacular fireball if it had entered Earth’s atmosphere - but most likely no one would have been there to see it as it flew over Antarctica in the beginning of their spring. There was a possibility it would have burnt down to a meteorite that could have one day been discovered though.

Alas, that didn’t happen as the asteroid made a pass around 428 km above the southern continent at around 1 AM UTC on October 1st. For comparison, that’s around the same height as the international space station’s orbit, which can vary from between 370 and 460 km. It would have been a very bad day if those two had found each other, but luckily the orbital space that far above the planet is vast, and even something as large as the ISS is easy to miss in that vastness.

An international team of researchers has succeeded in imaging two black holes orbiting each other at the center of a quasar called OJ287. Quasars are extremely bright galactic cores, whose light is produced when a supermassive black hole at the center of the galaxy devours the cosmic gas and dust around it.

In the past, astronomers have managed to image the black hole in the center of the Milky Way and in a nearby galaxy called Messier 87.

"Quasar OJ287 is so bright that it can be detected even by amateur astronomers with private telescopes. What is special about OJ287 is that it has been thought to harbor not one but two black holes circling each other in a 12-year orbit, which produces an easily recognizable pattern of light variations in the same period," says first author of the research article Mauri Valtonen from the University of Turku, Finland. The work is published in The Astrophysical Journal.

Africa needs energy. Nearly 600 million Africans—half the continent’s population—are without electricity, largely because of the continent’s limited distribution network, and Africans make up the vast majority of those worldwide without electricity access. But the European Union wants to change this.

At the end of September, the president of the European Commission, Ursula von der Leyen, announced a €545 million ($636 million) investment package to support renewable energy and electrification in Africa. New EU-funded projects will include a high-voltage transmission line in Côte d’Ivoire, the electrification of hundreds of rural communities in Cameroon, the exploitation of wind and hydro energy in Lesotho, and the installation of mini-grids in remote areas of Madagascar. The aim is both to increase access to electricity and move Africa off fossil fuels.

“A clean energy transition on the continent will create jobs, stability, growth, and the delivery of our global climate goals,” said Von der Leyen when making the announcement. “The European Union, with the Global Gateway investment plan, is fully committed to supporting Africa on its clean energy path.” The investment program could create 38 million green jobs in Africa by 2030, the EU estimates.

Global Gateway is a European initiative to build infrastructure around the world, with Africa its top priority. It has humanitarian and environmental intentions, but behind these sits a strong geopolitical objective: to provide an alternative to China’s Belt and Road Initiative.

Launched in 2013, this Chinese funding program has invested over $1.3 trillion in building and operating roads, ports, energy, and telecommunications networks in more than a hundred countries around the world, from Asia to Africa to Latin America. Constructing, connecting, and controlling crucial facilities worldwide is a way of projecting power, and the Belt and Road Initiative has provided China with political influence around the world. At the same time, it has tied countries to the Chinese economy and provided a market for Chinese industrial services.

The Global Gateway, launched in 2021, is the EU’s own attempt to use funding to build influence in regions relevant to its interests—which includes Africa. The continent has significant deposits of critical minerals vital for tech and the green transition, such as cobalt in the Democratic Republic of the Congo, lithium in Zimbabwe, copper in Zambia, and manganese in Gabon. China, with its mining companies, is already very active in these countries.

“From the outset, the Global Gateway has been described as the European Union’s attempt to rival the Belt and Road Initiative’s overseas infrastructure investment funds. At €300 billion through 2027, however, it is a David-versus-Goliath-style undertaking,” says Gabriele Rosana, an associate fellow at the Institute of International Affairs in Rome. China has already been investing heavily in clean energy in Africa, and with far fewer constraints. “The Union is operating in a system of precise rules, stakes, and constraints unknown to Chinese centralism,” Rosana says.

Dark matter is an enigmatic form of matter not expected to emit light, yet it is essential to understanding how the rich tapestry of stars and galaxies we see in the night sky evolved. As a fundamental building block of the universe, a key question for astronomers is whether dark matter is smooth or clumpy, as this could reveal what it is made of. Since dark matter cannot be observed directly, its properties can only be determined by observing the gravitational lensing effect, whereby the light from a more distant object is distorted and deflected by the gravity of the dark object.

"Hunting for dark objects that do not seem to emit any light is clearly challenging," said Devon Powell at the Max Planck Institute for Astrophysics and lead author of the study. "Since we can't see them directly, we instead use very distant galaxies as a backlight to look for their gravitational imprints."

Europe must quickly get its own reusable rocket launcher to catch up to billionaire Elon Musk's dominant SpaceX, European Space Agency director Josef Aschbacher told AFP in an interview.

While the US company has an overwhelming lead in the booming space launch industry, a series of setbacks, including Russia's withdrawal of its rockets, left Europe without an independent way to blast its missions into space.

That year-long hiatus ended with the first launch of Europe's much-delayed Ariane 6 rocket in July 2024. But the system is not reusable, unlike SpaceX's Falcon 9 workhorse.

"We have to really catch up and make sure that we come to the market with a reusable launcher relatively fast," Aschbacher said at AFP's headquarters in Paris.

"We are on the right path" to getting this done, he added.

'Paradigm shift'
The ESA has already announced a shortlist of five European aerospace companies bidding to build the continent's first reusable rocket launch system.

That number will be narrowed down to two—or even one—at the agency's ministerial council in the German city of Bremen next month, Aschbacher said.

"Ariane 6 is an excellent rocket—it's very precise," Aschbacher said. "We have now had three launches," with two more expected before the year's end, he added.

Despite finally getting Ariane 6 and the new, smaller Vega C launcher off the ground, the ESA has decided on a "paradigm shift," Aschbacher said.

Marking a defining moment in the “historic shift” away from fossil fuels, renewable energy surpassed coal to become the world’s largest source of electricity in the first half of 2025.

The latest report from Ember shows that solar and wind power grew faster than global electricity demand, with solar alone covering 83 percent of the increase and shattering records worldwide. Amidst this global rise, output from renewables overtook coal for the first time on record for the first six months of this year. 

“We are seeing the first signs of a crucial turning point,” Małgorzata Wiatros-Motyka, Senior Electricity Analyst at Ember, said in a statement. “Solar and wind are now growing fast enough to meet the world’s growing appetite for electricity. This marks the beginning of a shift where clean power is keeping pace with demand growth.”

Solar power is growing faster than ever, with a record 31 percent increase in the first half of 2025. China accounted for 55 percent of this growth, followed by the US (14 percent), the EU (12 percent), India (5.6 percent), and Brazil (3.2 percent), while the rest of the world contributed just 9 percent. 

Nevertheless, several countries set new records in terms of solar power. Among the top 20 solar producers, seven nations – including Hungary, Greece, the Netherlands, Pakistan, Spain, Australia, and Germany – generated at least 20 percent of their electricity from solar in the first six months of 2025.

Fungi are best known for returning dead, organic matter to the Earth, but materials scientists are exploring whether they could someday help our bodies repair, in the form of special hydrogels.

To play a role in biomedical settings, a hydrogel needs a multilayered structure like our own skin, cartilage and muscles. While some engineers are working on synthetic versions that mimic biology, University of Utah scientists have found a hydrogel that literally has a life of its own.

Marquandomyces marquandii is a common species of soil mold, and a promising candidate for the job. This fungus has had a bit of an identity crisis, being misclassified as Paecilomyces marquandii until it was reassigned to its own genus in 2020. Soon, it may be able to add the role of 'bio-integrated hydrogel' to its resume.

Bio-integrated hydrogels are created from organisms that we know form crosslinked, intricate network structures that may be capable of standing in for our own soft tissues.

"Hydrogels are regarded as a promising alternative for applications in tissue regeneration and engineering, cell culture scaffolds, cell bioreactors, and wearable devices, owing to their ability to closely mimic the viscoelastic properties of soft tissues," writes lead author Atul Agrawal, an engineer at the University of Utah, and his collaborators.

Sometimes the best families are the ones you make for yourself—this elephant has formed a herd of her own with a group of buffalo who have learned to understand her. 🐘

The brain seems to “rescue” weak memories when they are tied to a significant or surprising experience. This new understanding of how emotion shapes recall could lead to better memory treatments and smarter learning strategies.

Why Some Memories Stick While Others Fade
Some memories come rushing back with vivid clarity, as if they happened only moments ago. Others feel distant and incomplete, like faint outlines on a page, while some remain completely inaccessible, no matter how hard we try to remember. Why does the brain preserve certain experiences so firmly while allowing others to fade away?

Researchers at Boston University may have uncovered an explanation. Their new study suggests that ordinary memories become more durable when they are linked to a meaningful or emotionally charged event—something unexpected, rewarding, or intense. For instance, if you suddenly realize your Powerball numbers have won, you are likely to recall the mundane details of what you were doing just before that moment. The findings, published in Science Advances, could pave the way for new methods to help people with memory impairments and even improve how students retain challenging information.

Stabilizing Fragile Memories Through Emotion
“Memory isn’t just a passive recording device: Our brains decide what matters, and emotional events can reach back in time to stabilize fragile memories,” says Robert M.G. Reinhart, a BU College of Arts & Sciences associate professor of psychological and brain sciences. “Developing strategies to strengthen useful memories, or weaken harmful ones, is a longstanding goal in cognitive neuroscience. Our study suggests that emotional salience could be harnessed in precise ways to achieve those goals.”

In their paper, Reinhart and his team illustrate this idea with a scene from Yellowstone National Park: a hiker unexpectedly encountering a herd of bison. According to the researchers, the awe of that experience can help preserve not just the extraordinary sight itself but also the smaller, seemingly insignificant details surrounding it—like noticing a rock on the trail or catching a glimpse of an animal in the brush.

“The question is, What are the mechanisms for that?” says Reinhart, who’s also a College of Engineering associate professor of biomedical engineering and a faculty member at the BU Center for Systems Neuroscience. “That’s what we tried to uncover, how the brain selectively strengthens those fragile memories.”

Betelgeuse, the brilliant red star marking Orion's shoulder, has long been suspected of harbouring a secret. I have to confess, Betelgeuse holds a special place in my heart as the first star I ever looked at through a telescope as a child, so learning that astronomers theorised this massive supergiant wasn't alone made it even more intriguing. Proving it, however, required catching a fleeting alignment and deploying some of our most powerful space telescopes in a race against time. Now, researchers from Carnegie Mellon University have finally confirmed what many suspected, Betelgeuse does indeed have a companion star, though not quite the type anyone expected.

The challenge of detecting anything near Betelgeuse cannot be overstated. The star is roughly 700 times larger than our Sun and thousands of times brighter, making it extraordinarily difficult to spot nearby objects. It's rather like trying to photograph a firefly hovering next to a car headlight, perhaps worse! The brightness difference between Betelgeuse and its tiny companion is, as Anna O'Grady, a McWilliams Postdoctoral Fellow at Carnegie Mellon, put it, "absolutely insane."

The breakthrough came during a critical observational window around 6th December, when the companion, affectionately nicknamed "Betelbuddy," reached its maximum separation from the supergiant before disappearing behind it for another two years. The timing demanded swift action. O'Grady and her team secured Director's Discretionary Time on both NASA's Chandra X-ray Observatory and the Hubble Space Telescope, reserved time typically granted only for the most exceptional research opportunities. Having two such proposals accepted simultaneously speaks to the significance of the discovery.

Using Chandra's X-ray observations, the deepest ever taken of Betelgeuse, O'Grady's team searched for evidence of accretion, the telltale signature of compact objects like neutron stars or white dwarfs pulling material from their surroundings. They found nothing. No accretion signature appeared in the data, ruling out these possibilities. Instead, the findings published in The Astrophysical Journal point to something more ordinary yet equally fascinating, a young stellar object roughly the size of our Sun.

Glaciers appear to be resisting the effects of climate change by cooling the air that comes into contact with their icy surfaces. But this natural defense may not last much longer. Researchers from the Pellicciotti group at the Institute of Science and Technology Austria (ISTA) have assembled and reanalyzed an extensive global dataset of glacier observations, offering new insight into this temporary phenomenon.

According to their study, published in Nature Climate Change, glaciers are expected to reach the height of their self-cooling ability within the next decade. After that point, near-surface temperatures are projected to climb more rapidly, leading to faster melting and retreat.

Postdoctoral researcher Thomas Shaw vividly recalls a summer day in August 2022 that marked one of his key field experiences. Working under Francesca Pellicciotti at ISTA, Shaw stood atop Switzerland’s Glacier de Corbassière, 2,600 meters above sea level, gathering crucial data about the glacier’s condition. The weather was deceptively mild, with clear skies and a temperature of 17 degrees Celsius, unusual for someone standing on a glacier.

So, are glaciers “keeping their cool” a little too well? While average global temperatures continue to rise, glacier surfaces appear to warm more slowly. In the Himalayas, some of the world’s largest glaciers even send frigid air cascading down their slopes, forming cold winds that help protect their ecosystems. Yet scientists caution that this self-cooling process does not signal long-term resilience. Instead, it may be a fleeting response to a warming world.

A new study led by Shaw demonstrates that this reaction of glaciers is likely to reach its peak in the 2030s. “The more the climate warms, the more it will trigger the glaciers to cool their own microclimate and local environments down-valley,” says Shaw. “But this effect will not last long, and a trend shift will ensue before the middle of the century.” From then on, the glaciers’ melting and fragmentation due to human-caused climate change will intensify, and their near-surface temperatures will rise more rapidly, hastening their decline.