Each time the Moon covers the Sun during a total solar eclipse — darkening daytime skies and briefly revealing the Sun’s ethereal outer atmosphere, the corona — it presents new opportunities to better understand our star and its influence on Earth.

On Wednesday, Aug. 12, as the next total solar eclipse sweeps over Greenland, Iceland, and Spain, NASA-funded science teams will be chasing the Moon’s shadow with a high-altitude jet and scientific balloons to investigate the Sun’s dynamics and how the temporary darkening of our skies affects our atmosphere.

“From our unique perspective on Earth during a total solar eclipse, scientists can study the Sun’s corona in a way we can’t from anywhere else in the solar system,” said Kelly Korreck, eclipse program manager at NASA Headquarters in Washington. “The Sun impacts our daily life, satellites, and astronauts in space, and we can take advantage of this moment to advance our understanding of that influence.”

High-flying jet to record solar dynamics

Soaring in the nose cone of NASA’s WB-57 high-altitude research aircraft is a suite of four cameras to take high-resolution images of the corona in several different wavelengths of visible and infrared light. Part of an instrument developed by the NASA Scientifically Calibrated In-Flight Imagery (SCIFLI) team at NASA’s Langley Research Center in Hampton, Virginia, the cameras will capture at least 20 images per second, recording structures, outflows, and rapid changes in the corona during the total solar eclipse.

With these images, scientists hope to learn more about the formation of prominences (solar material that gets suspended above the Sun’s surface), better understand the corona and how it gets heated to nearly a million degrees, and investigate how material in the corona and the solar wind are related, which flows out from the Sun across the solar system.

By chasing the Moon’s shadow, the jet will extend how long the cameras can observe the corona. On the ground, the longest anyone will be able to see the corona is two minutes and 18 seconds. But flying along the eclipse path at 460 miles per hour, the jet’s view of the corona will last nearly three minutes.

NASA’s WB-57 will fly at 50,000 feet, above any clouds that might obscure the view of the corona from the ground. The altitude also allows the cameras to observe some infrared wavelengths that get absorbed by the lower atmosphere before reaching the ground, and the corona only has been observed in those wavelengths a few times before.

The instrument, called SCIFLI Multispectral Airborne Imager, or SAMI, also flew on a WB-57 during the total solar eclipse on April 8, 2024, providing valuable imagery and information about the corona. However, the study’s principal investigator, Amir Caspi of the Southwest Research Institute in Boulder, Colorado, says each total solar eclipse provides new opportunities to learn more about the corona.

“The Sun is always changing,” Caspi said. “Every eclipse is different. So we could see things we didn’t see before. And we learn from each eclipse how to better observe the next one.”

Caspi’s team also is making some enhancements for the 2026 campaign based on lessons learned in 2024. For example, the team will adjust exposure times to better capture bright features that were overexposed in 2024 imagery. They will also leverage software developed since 2024 to process and analyze the data sooner than before.

The experiment is funded by NASA’s Heliophysics Low Cost Access to Space Program.

Balloons to watch atmospheric changes

When a total solar eclipse suddenly turns daytime skies dark, our atmosphere changes in ways we don’t yet fully understand.

The NASA-supported Nationwide Eclipse Ballooning Project, led by Angela Des Jardins at Montana State University, is sending students from several U.S. universities to Iceland and Spain to launch scientific balloons before, during, and after the eclipse to better understand those changes.

In Iceland, two teams will launch a total of 80 balloons starting 18 hours before the eclipse until eight hours afterward to study how the eclipse affects Earth’s “boundary layer,” the part of the atmosphere that touches the ground. The thickness of the boundary layer changes depending on factors such as surface temperature and moisture in the air.

Previous balloon flights during solar eclipses in October 2023 and April 2024 showed that the boundary layer collapsed, or decreased in thickness, in locations with clear skies but not where there were cloudy skies. Scientists wonder whether that will be different in Iceland in 2026. Changes in the boundary layer are driven by the day-night cycle. However, in Iceland in August, the days are long and nights are short, so the nighttime influences might not be as strong as in 2023 or 2024.

“Will this eclipse be able to collapse the boundary layer?” said Matthew Bernards, a chemical engineering professor at the University of Idaho, who leads one of the Iceland teams.

In Spain, three balloon teams will launch a total of six balloons with 360-degree cameras to image the eclipse shadow from above. These balloons also will include instruments designed to measure levels of ozone in the atmosphere, which requires sunlight to form. Similar balloon experiments showed that ozone decreased during totality in April 2024. Scientists wonder whether there will be differences with this eclipse, particularly since it happens at a later time of day and during a different season.

Follow along

While the total solar eclipse won’t be visible in the U.S., some parts of the country will be able to see a partial solar eclipse. Learn more about where to see the eclipse and how to view it safely.

by Vanessa Thomas
NASA’s Goddard Space Flight Center, Greenbelt, Md.

Lee esta historia en español aquí.

Anthropic and OpenAI are clashing with the rest of the tech industry over whether “open-source” models from China should be freely available or restricted.

On July 3, one of NASA’s two Mars-destined ESCAPADE (Escape and Plasma Acceleration and Dynamics Explorers) spacecraft captured photos of Earth and the Moon in visible and thermal infrared light. At the time, the spacecraft was 363,250 miles (584,600 kilometers) from Earth and 115,600 miles (186,100 kilometers) from the Moon, making the Moon appear relatively large.

Taken with the Sun only partly illuminating Earth and the Moon, the visible light image shows the two bodies as crescents, with only around 8% of each face sunlit. Yet in the thermal infrared image, the shadowed hemisphere of Earth is illuminated by its own heat from both the atmosphere and surface, glowing at minus 10 to minus 44 degrees Fahrenheit (250 to 280 kelvins). Without the insulating blankets of oceans and atmospheres, the Moon’s far side remains at a much cooler minus 280 degrees Fahrenheit (100 kelvins).

The ESCAPADE mission used its Visible and Infrared Observation System cameras, provided by Northern Arizona University in Flagstaff, to capture the images, which are more than just road trip photo album snaps.

“We are thrilled that ESCAPADE was able to accommodate these excellent space-qualified cameras which will search for visible Martian aurora and investigate thermal properties of the Martian surface and atmosphere,” said Rob Lillis, the mission’s principal investigator at the University of California, Berkeley. “Since Earth and the Moon are well-known targets, imaging them provides an important calibration check for ESCAPADE’s cameras.”

The ESCAPADE spacecraft, which were built by Rocket Lab, are currently in a “loiter” orbit around Lagrange point 2, a location in space about a million miles from Earth. In November 2026, the spacecraft will fly by Earth to use the planet’s gravity to slingshot their way to Mars. When the spacecraft arrive in September 2027, they will study how a million-mile-per-hour stream of material flowing from the Sun, known as solar wind, interacts with the Martian environment and how that drives atmospheric loss at the Red Planet.

The ESCAPADE mission is funded by NASA’s Heliophysics Division and is part of the NASA Small Innovative Missions for Planetary Exploration program. The UC Berkeley’s Space Sciences Laboratory leads the mission with key partners Rocket Lab; NASA’s Goddard Space Flight Center in Greenbelt, Maryland; Embry-Riddle Aeronautical University; Advanced Space; and Blue Origin.

By Mara Johnson-Groh
NASA’s Goddard Space Flight Center, Greenbelt, Md.

The post NASA’s ESCAPADE Snaps Family Portrait of Earth, Moon appeared first on NASA Science.

On July 3, one of NASA’s two Mars-destined ESCAPADE (Escape and Plasma Acceleration and Dynamics Explorers) spacecraft captured photos of Earth and the Moon in visible and thermal infrared light. At the time, the spacecraft was 363,250 miles (584,600 kilometers) from Earth and 115,600 miles (186,100 kilometers) from the Moon, making the Moon appear relatively large.

Taken with the Sun only partly illuminating Earth and the Moon, the visible light image shows the two bodies as crescents, with only around 8% of each face sunlit. Yet in the thermal infrared image, the shadowed hemisphere of Earth is illuminated by its own heat from both the atmosphere and surface, glowing at minus 10 to minus 44 degrees Fahrenheit (250 to 280 kelvins). Without the insulating blankets of oceans and atmospheres, the Moon’s far side remains at a much cooler minus 280 degrees Fahrenheit (100 kelvins).

The ESCAPADE mission used its Visible and Infrared Observation System cameras, provided by Northern Arizona University in Flagstaff, to capture the images, which are more than just road trip photo album snaps.

“We are thrilled that ESCAPADE was able to accommodate these excellent space-qualified cameras which will search for visible Martian aurora and investigate thermal properties of the Martian surface and atmosphere,” said Rob Lillis, the mission’s principal investigator at the University of California, Berkeley. “Since Earth and the Moon are well-known targets, imaging them provides an important calibration check for ESCAPADE’s cameras.”

The ESCAPADE spacecraft, which were built by Rocket Lab, are currently in a “loiter” orbit around Lagrange point 2, a location in space about a million miles from Earth. In November 2026, the spacecraft will fly by Earth to use the planet’s gravity to slingshot their way to Mars. When the spacecraft arrive in September 2027, they will study how a million-mile-per-hour stream of material flowing from the Sun, known as solar wind, interacts with the Martian environment and how that drives atmospheric loss at the Red Planet.

The ESCAPADE mission is funded by NASA’s Heliophysics Division and is part of the NASA Small Innovative Missions for Planetary Exploration program. The UC Berkeley’s Space Sciences Laboratory leads the mission with key partners Rocket Lab; NASA’s Goddard Space Flight Center in Greenbelt, Maryland; Embry-Riddle Aeronautical University; Advanced Space; and Blue Origin.

By Mara Johnson-Groh
NASA’s Goddard Space Flight Center, Greenbelt, Md.

Around 4.6 billion years ago, an immense cloud of gas and dust in space collapsed in on itself. As it collapsed, gravity pulled most of the material toward several small points, one of which would eventually become our Sun. The other points formed other stars in what scientists call an open cluster. 

During this early stage of the Sun’s life, it was surrounded by a swirling disk of leftover material aligned with its equator, known as a protoplanetary disk. Eventually, this disk condensed to form the planets that make up our solar system. This process normally results in a system with a star at its center, and the planets orbiting the plane of the star’s equator. 

However, scientists have found that this scenario doesn’t quite hold for our solar system. The planets in our solar system orbit the Sun in a single plane offset from the Sun’s equator by approximately 6°. The fact that the planets are in the same orbital plane suggests that the protoplanetary disk model of solar system formation is correct, since the odds of the Sun capturing 8 rogue planets in this arrangement are astronomically low. So, what threw the planets in our solar system off-kilter?

To determine what caused the solar system to tilt, Daohai Li at Queen Mary University of London recently used the computer program NBODY6++ to model different versions of the open cluster from which the Sun came. In these simulations, he varied the number of stars in the cluster, from 500 to 2,000 to 8,000. He also varied the radius of the cluster, from 0.25 to 1 to 4 parsecs (8 to 30 to 100 trillion kilometers or 5 to 20 to 70 trillion miles). Finally, he varied the percentage of stars with a binary companion from 10% to 50% to 90%. Li assigned each star a randomly generated initial mass, starting position, and velocity, and simulated their interactions for 400 million years.

First, Li examined the simulations to identify stars with masses approximately equal to the Sun’s. From this group of solar-massed stars, Li found ones that left the cluster after 400 million years as a single star, after either forming alone or having lost a former companion star. He proposed that these stars were the most similar to the Sun and could thus host a simulated solar system.

Li then simulated the planets and their orbits as they would have formed on these potential host stars. To simplify this process, Li only simulated the 4 giant planets, Jupiter, Saturn, Uranus, and Neptune, which dominate planetary behavior in our solar system. He modeled these solar systems independently for 200 million years to ensure they would remain intact and used those that did for statistical analysis of the solar system’s past.

Overall, Li discovered 2 scenarios that could explain the solar system’s tilt. In the first, the primordial solar system was jostled by many distant neighboring stars in its cluster. This jostling tilts the planets’ orbits, but it does so randomly. Therefore, this scenario would make it unlikely for the planets to remain in the same orbital plane. It would also cause them to orbit the Sun faster and more chaotically than in our solar system.

In the second scenario, the Sun had a temporary companion star that it either formed with or briefly encountered before separating. When this occurred, the simulated planets’ orbits all tilted together. Stars that formed with a binary companion had a 10% chance of tilting their planets’ orbits by 6° or more, while stars that formed alone had a less than 0.1% chance. 

Li concluded that the solar system could have tilted as a result of interactions between the Sun and a temporary companion star within its parent cluster. However, he acknowledged that the model strongly depends on how closely a star passes by the Sun, since the closer a star passes, the more it disturbs the solar system. Despite this uncertainty, it’s possible that somewhere in space is the Sun’s twin or former neighbor that we haven’t seen in eons, and that’s what made our solar system crooked!

The post The Sun’s twin star may have tilted the planets’ orbits appeared first on Sciworthy.

Planetary researchers have found the first evidence that bursts of energetic particles from the Sun could warm the lower atmosphere of Mars during massive dust storms, hinting at an unexpected link between space weather and Martian climate.

The post Space Weather May Warp Martian Weather during Dust Storms, Planetary Scientists Suggest appeared first on Sci.News: Breaking Science News.

Many observations of solar flares suffer from saturation and blooming, causing crucial information to be lost. Researchers recently validated a technique for retrieving information from saturated flare images, unlocking a treasure trove of powerful solar flares for examination.

Solutions for Saturation

Since 2010, the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory (SDO) has been capturing nearly continuous extreme-ultraviolet images of the Sun’s disk, revealing our star’s dramatic high-energy behavior. Though SDO/AIA’s observations have transformed our understanding of the Sun’s activity, they have limitations: powerful solar flares can saturate the detector, spilling charge into nearby pixels.

This saturation and overflow compromises our ability to study the most energetic solar flares — but the “lost” information may actually be recoverable. When light from an intense flare enters SDO’s instruments, not all of it pools in the saturated region of the detector: some of the light is diffracted by the optics, and by mathematically inverting this pattern of diffracted light, researchers can attempt to extract the encoded information about the saturated region. Researchers have used this technique for more than a decade, but options for validating the results were limited until now.

Solar Orbiter Lends a Hand

Launched almost 10 years to the day after SDO, the Solar Orbiter spacecraft provides an excellent opportunity to test inversion techniques for recovering information from saturated solar images. Solar Orbiter’s Extreme Ultraviolet Imager snaps brief photos of the Sun at a rapid cadence, and its images remain unsaturated even when faced with energetic solar flares.

As described in a recent research article by Sabrina Guastavino (University of Genoa; Italian National Institute for Astrophysics) and collaborators, the ideal setup for testing the inversion technique arose on 19 March 2024, when SDO and Solar Orbiter both viewed a solar flare while separated by just 1 degree in longitude.

Guastavino’s team aligned and reprojected the data, accounting for the slightly different viewing angles of the two spacecraft, then applied an algorithm called Adaptive SE-DESAT to reconstruct the flux within the saturated portion of the SDO image. The team compared the desaturated SDO images to the unsaturated Solar Orbiter images over the course of the flare, finding the same flare morphology and similar time evolution between the two data sets.

A Treasure Trove of Desaturated Data

Overall, these results demonstrate the effectiveness of the inversion technique, though Guastavino and coauthors noted that improvements could be made during the impulsive phase of the flare, when the emission is increasing. The team identified several reasons why the results may not match during this phase, including rapid evolution of the flare during individual exposures.

Despite these areas that require further attention, the validation of this technique unlocks 16 years of solar flare observations from SDO. This especially enhances our sample of powerful solar flares, increasing the available records of the most energetic solar flares by orders of magnitude.

Citation

“Validation of an Extreme-Ultraviolet Desaturation Technique for the Atmospheric Imaging Assembly on Board the Solar Dynamics Observatory Using Observations from the Extreme Ultraviolet Imager on Board Solar Orbiter,” Sabrina Guastavino et al 2026 ApJL 1005 L50. doi:10.3847/2041-8213/ae7d2e

The post When the Spacecraft Align: Rescuing Saturated Images of Solar Flares appeared first on AAS Nova.

One of Taika Waititi's greatest strengths as a director is his unique voice; he's able to bring a light touch to tragedy (Jojo Rabbit) and a gentle sadness to offbeat comedy (Our Flag Means Death). That makes him an excellent choice to direct Klara and the Sun, based on the novel by Kazuo Ishiguro. Sony Pictures just released the first trailer, and it's giving strong Hunt for the Wilderpeople vibes—a good thing, from my perspective, since that's my favorite Waititi film.

Per the official premise:

Based on the bestselling novel from Nobel Prize winner Kazuo Ishiguro and written and directed by Academy Award winner Taika Waititi, Klara and the Sun introduces audiences to Klara (Jenna Ortega), an Artificial Friend who wants nothing more than to find the perfect home. When Klara meets Josie (Mia Tharia), each immediately senses a kindred spirit in the other. Josie has a fraught relationship with her mother (Amy Adams), and they’ve suffered great loss, but Klara’s innocent wonder and unwavering loyalty begin to heal the family and bring light to Josie’s complicated world.

The cast also includes Natasha Lyonne as an artificial friend (AF) store manager; Rachel House as the housekeeper, Melania; Aran Murphy (son of Cillian Murphy) as Josie's best friend, Rick; and Sophia Bryant-Taukiri as Josie's older sister, Sal. Steve Buscemi and Harry Greenwood also appear in as-yet-undisclosed roles.

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They make much of the gear that goes into giant data centers. Demand for their products is shifting the balance of tech power.

These results could benefit space weather forecasts.

NASA’s Parker Solar Probe completed its 28th close approach to the Sun on June 8, again matching its record distance of 3.8 million miles from the solar surface. The flyby allowed the spacecraft to continue its measurements of the solar wind and solar activity at their source, while adding to our understanding of how the Sun’s atmosphere changes throughout the solar cycle.

The spacecraft checked in with flight controllers at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland — where Parker Solar Probe was designed and built — on Thursday, transmitting a beacon tone that indicated its systems were operating normally. Zooming around the Sun on a trajectory that limited communications with Earth, Parker had been out of contact and operating autonomously for nine days around its closest approach, as planned.
 
During this solar encounter, which started June 3 and ends Saturday, June 13, Parker’s four scientific instrument packages gathered data from inside the Sun’s atmosphere, or corona. Parker will begin returning detailed spacecraft telemetry on June 14, with science data transmission set to run from Wednesday, June 17 to Tuesday, June 30.
 
Parker’s observations of the solar wind and solar events, such as coronal mass ejections and the aftermaths of flares, are critical to advancing humanity’s understanding of the Sun and the phenomena that drive high-energy space weather events that pose risks to astronauts, satellites, air travel, and even power grids on Earth. Understanding the fundamental physics of space weather enables more reliable prediction of astronaut safety during future deep-space missions to the Moon and Mars.
 
Parker also equaled its record-setting speed of 430,000 mph — a mark that, like Parker’s distance to the Sun, was set during a close approach on Dec. 24, 2024, and matched during five flybys since, most recently on March 11. Parker will continue matching these speed and distance records during future flybys.
 
Through all six close approaches, mission leads say, the spacecraft has remained in excellent condition. While Parker doesn’t have a temperature sensor on the front of its heat shield — known as the Thermal Protection System, or TPS — the team can estimate through models that the heat shield reaches temperatures of about 1,700 degrees Fahrenheit at closest approach.

“The heat shield material is incredibly light and fragile, but the thermal design, as well as the software that keeps the spacecraft pointing the TPS toward the Sun, have been outstanding,” said John Wirzburger, Parker Solar Probe mission systems engineer at APL. “It’s a real tribute to the team that designed, built, and operates Parker Solar Probe.”
 
Meanwhile, the team can measure the temperature of the barrier blanketing below the heat shield, and the actual spacecraft temperature has remained consistent on each pass.
 
“That temperature consistency is a major indicator of spacecraft health,” said Wirzburger. “It tells us the heat shield isn’t degrading. If it were cracking or weakening, we’d see temperatures drift upward as more heat leaked through.”
 
Parker launched in August 2018. At the time, the Sun was near the minimum of its 11-year activity cycle. In 2024, representatives from NASA, the National Oceanic and Atmospheric Administration (NOAA), and the international Solar Cycle Prediction Panel announced that the Sun had reached its solar maximum period. Parker’s 28 encounters with the Sun reflect this change over time, sampling the Sun’s atmosphere from quiet to very active periods. Parker Solar Probe will remain in this orbit around the Sun and continue making observations into the declining phase of solar activity.
 
The next steps for the mission in late 2026 and beyond are under NASA review.
 
Parker Solar Probe was developed as a part of NASA’s Living With a Star (LWS) program to explore aspects of the Sun-Earth system that directly affect life and society. The LWS program is managed by the agency’s Goddard Space Flight Center in Greenbelt, Maryland, for NASA’s Science Mission Directorate in Washington. Johns Hopkins APL manages Parker Solar Probe for NASA and designed, built, and now operates the mission.
 
Mike Buckley, Johns Hopkins Applied Physics Laboratory

The post Parker Solar Probe Makes 28th Close Pass of Sun appeared first on NASA Science.

Eugene Parker, pioneer of theoretical solar and plasma astrophysics, was born June 10, 1927. Parker revolutionized the field of heliophysics, notably by first proposing the existence of the solar wind — a stream of charged particles ejected from the Sun — in 1958. His theory was confirmed by Mariner II in 1962. Among many otherContinue reading "June 10, 1927: The birth of Eugene Parker"

The post June 10, 1927: The birth of Eugene Parker appeared first on Astronomy Magazine.

The Sun’s activity history, the sources of tiny jets, and how magnetic fields might impact space weather forecasts: today’s Monthly Roundup introduces a trio of recent research articles from the Astrophysical Journal that tackle hot topics in solar physics.

From 1755 to 2020: Reconstructing Centuries of Solar Activity

Since the 1970s, regular monitoring of the Sun’s magnetic field has allowed researchers to decipher the Sun’s behavior as it cycles through periods of low and high activity. But what resources exist for studying the Sun’s past behavior? To investigate the long-term behavior of the Sun, researchers reach for historical records of sunspots, which stretch back to the 1700s.

Bibhuti Kumar Jha (Southwest Research Institute) and collaborators explored whether historical records and modern statistics could be used to reconstruct the behavior of the solar magnetic field centuries into the past. Jha’s team used recorded sunspot numbers from 1755 to 2020 as an input for their newly developed Synthetic Active Region Generator, which generates synthetic solar active regions based on known statistics of these regions. This catalog of active regions becomes the input for the Advective Flux Transport model, which simulates the active regions as they emerge and evolve, allowing for an estimation of the magnetic field across the Sun’s disk.

Jha and coauthors found that this method successfully reproduced the expected large-scale behavior of the Sun’s magnetic field across multiple solar cycles, such as the reversal of the polarity of the solar magnetic field near the peak of the activity cycle. While this work highlights the impressive results obtained from combining historical sunspot records with modern sunspot statistics, the team pointed out that this method cannot accurately reproduce all quantities because of the nonlinear nature of the underlying physics. Future work will refine the model further, and in the meantime, the team’s simulated historical magnetic field maps will be made publicly available.

Where Do the Tiniest Coronal Jets Come From?

The Sun’s atmosphere is filled with an ever-shifting maze of magnetic field lines, which reconfigure and release pent-up magnetic energy in a process called magnetic reconnection. Magnetic reconnection can launch particles and heat plasma, and it’s thought to be responsible for driving jets on a variety of scales in the Sun’s tenuous outer atmosphere, or corona. Annu Bura (Indian Institute of Astrophysics; Pondicherry University) and coauthors investigated the physical origins of the smallest of these reconnection driven jets, picoflare jets, using data from the Extreme Ultraviolet Imager on board Solar Orbiter. Solar Orbiter has ventured within 0.3 au of the Sun, and its Extreme Ultraviolet Imager has returned exceptionally precise high-energy images of our home star.

Bura and collaborators identified picoflare jets by the presence of a hot, bright spire coupled with a cool, dark streak, forming a structure shaped like the letter “Y” upside down. They found that the bright and dark features were on average 650 and 490 kilometers wide, respectively, with a typical jet length of 16,900 kilometers. They also found that the bright features moved more quickly than the dark features, and the jets tended to last about 6 minutes. Overall, these measurements place the jets in between the scales expected for picoflare jets and slightly larger features called jetlets, though the energies are consistent with expectations for picoflare jets.

Using radiation magnetohydrodynamics simulations, the team explored the origins of their sample of jets. The simulations suggested that the bright features arose from hot, tenuous coronal plasma, while the accompanying dark features were due to cooler, denser plasma venturing upward from deeper in the Sun’s atmosphere, in the chromosphere. Overall, the simulations and observations support a picture in which picoflare-scale jets are driven by magnetic reconnection after magnetic flux emerges through the Sun’s surface. This echoes the formation route of larger coronal jets, suggesting that this process may apply to a wide range of physical scales.

Investigating the Influence of the Solar Polar Magnetic Field

The vast majority of our observations of the Sun have come from within a few degrees of the ecliptic plane, either from telescopes situated on Earth’s surface or from spacecraft that stuck close to the plane of our solar system. With rare but notable exceptions — the Ulysses spacecraft, which measured the Sun’s magnetic field and plasma environment from a near-polar orbit, and Solar Orbiter, which took the first-ever image of the Sun’s poles in November 2025 — the Sun’s poles have remained hidden from our instruments.

Our limited knowledge of the Sun’s polar magnetic field has consequences for our ability to model space weather events like coronal mass ejections. A team led by Xiao Zhang (Chinese Academy of Sciences; University of Chinese Academy of Sciences) has used numerical simulations to investigate how solar polar magnetic field conditions influence the propagation of a coronal mass ejection (CME) through the solar system.

The team simulated a CME from 4 December 2021, which was observed by the BepiColombo spacecraft at Mercury and Tianwen-1 and MAVEN at Mars. The simulations showed that as the polar magnetic field strength increases, the CME’s movement through the solar system becomes slower. CMEs typically expand as they billow outward from the solar corona and sweep past the planets; increasing the polar magnetic field strength slowed the CME’s expansion as well. A stronger polar magnetic field also alters the background solar wind, making it slower and denser. Overall, these results demonstrate that the strength of the Sun’s poorly constrained polar magnetic field can have a significant impact on the movement and evolution of a CME. In future work, Zhang’s team plans to expand their investigation to a larger sample of CMEs.

Citation

“Historical Reconstruction of Solar Surface Magnetism from Cycles 1–24 Using the Synthetic Active Region Generator and the Advective Flux Transport Model,” Bibhuti Kumar Jha et al 2026 ApJ 997 279. doi:10.3847/1538-4357/ae279a

“On the Origin of Coronal Picoflare Jets,” Annu Bura et al 2026 ApJ 1000 94. doi:10.3847/1538-4357/ae48e6

“Influence of Solar Polar Magnetic Fields on the Propagation of Coronal Mass Ejections,” Xiao Zhang et al 2026 ApJ 1000 200. doi:10.3847/1538-4357/ae4c54

The post Monthly Roundup: Science of the Sun appeared first on AAS Nova.

Revealed in high resolution, researchers have spotted complex twisting and braiding motions in fine threads of plasma suspended above a sunspot. The flow of material that followed this braiding provides evidence for magnetic reconnection.

Heating Up the Corona

One of the leading challenges for the field of solar physics is explaining how the temperature of the Sun skyrockets from roughly 6000K at its surface, or photosphere, to more than 10⁶K in its wispy corona. The top candidates for the resolution to this mystery are magnetohydrodynamic waves and magnetic reconnection, in which nearby field lines reorganize into a lower-energy configuration and release magnetic energy.

One way for magnetic reconnection to heat the corona is along magnetic fields that loop up into the corona and are anchored to the solar photosphere. The footprints of these field lines — the spots where they land in the photosphere — wiggle around in random ways. As this happens, the arcing magnetic field lines become braided together, and the twisted magnetic field can then undergo magnetic reconnection, heating the corona.

Braiding and Unbraiding

This process has been explored theoretically, but it’s been challenging to observe directly. As increasingly capable Sun-studying instruments have come online, though, researchers have been able to attain the high resolution needed to see this process at work.

Recently, Hechao Chen (Yunnan University; Peking University; Yunnan Key Laboratory of Solar Physics and Space Science) used data from the New Vacuum Solar Telescope, the Interface Region Imaging Spectrograph, and the Solar Dynamics Observatory to study the braiding and unbraiding of fine magnetic structures above a sunspot.

The images show a bundle of narrow strands of plasma stretching about 17,000–22,000 miles (28,000–36,000 kilometers). These plasma threads trace magnetic field lines as they emerge from the sunspot before diving down again in a network region, where the magnetic field is slightly enhanced at the border of a giant convective cell.

Driven by Reconnection

The plasma threads appear to lie nearly parallel to one another at the beginning of the observation. Images from all three facilities showed the plasma threads intertwining, providing evidence for the twisting of magnetic field lines predicted to happen when their footprints move around. (As further evidence for this footprint motion, the team also observed complicated flow patterns near one of the footprints.) This intertwining was followed by a sudden brightening where the threads were most tightly knotted, creating two bright “blobs” that traveled outward toward the footprints. Afterward, the threads resumed their nearly parallel state.

The team witnessed these bright points form and travel outward repeatedly, moving with projected velocities of 20–230 km/s. They posited that the motion and heating of these blobs of plasma was driven by the release of magnetic tension, and that the threads returned to a parallel configuration once reconnection was complete. They estimated that each of these events produced 10¹⁷ Joules, roughly the energy expected for small-scale reconnection events.

This work beautifully illustrates the process of magnetic reconnection on the Sun, showing how random motions can set the stage for the buildup of magnetic tension. The heating and acceleration of plasma that follows demonstrates how small-scale reconnection events like the ones shown here can provide the energy needed to heat the solar corona.

Citation

“Witnessing Magnetic Reconnection in Tangled Superpenumbral Fibrils Around a Sunspot,” Hechao Chen et al 2025 ApJ 995 94. doi:10.3847/1538-4357/ae12e9

The post Astronomers See Braided Magnetic Fields Above a Sunspot appeared first on AAS Nova.

What happens when pileups of solar wind plasma collide with Earth’s protective magnetosphere? New work uses machine learning to examine how strongly these events affect our planet’s magnetic field.

Plasma Pileups

Geomagnetic storms driven by solar activity paint night skies with glowing aurorae, but they also threaten spacecraft electronics with showers of high-energy particles. While immense eruptions of solar plasma and magnetic fields called coronal mass ejections are the most infamous example of solar activity, a team led by Yudong Ye (Sun Yat-Sen University) recently focused on another, less destructive form of activity: stream interaction regions.

Stream interaction regions arise when slow-moving solar wind is struck from behind by faster-moving solar wind emitted later. The collision of the two solar wind streams creates a tangle of compressed plasma and strong magnetic fields capable of peeling back Earth’s protective magnetosphere and dumping in high-energy charged particles, with beautiful yet harmful results.

Machine Learning Method

Though stream interaction regions are less disruptive than coronal mass ejections, they’re far more common; they frequently needle Earth’s magnetosphere, especially during the calmer years of the Sun’s activity cycle. Predicting how strongly a stream interaction region will influence Earth’s magnetosphere — in other words, how geoeffective it is — is challenging, however. When two streams of solar wind collide, their properties combine in complex and nonlinear ways that traditional statistical investigations have struggled to pin down.

Now, Ye and collaborators have used machine learning to study the properties and impact of stream interaction regions in a physically meaningful way. They performed their study on a sample of 879 stream interaction events for which there is abundant information, such as temperature, magnetic field strength and direction, and solar wind conditions before and after the event.

Ye’s team based their framework on a support vector machine classifier: a classical machine learning algorithm that draws a mathematical boundary between groups of data while maximizing the distance between the boundary and the data points nearest to the dividing line. The support vector machine algorithm is well-suited to the task of modeling the geoeffectiveness of stream interaction regions because it doesn’t require a particularly vast dataset, can tolerate misclassified events, and allows for a physical interpretation of the results.

A Physical Interpretation

The team first reined in the model’s complexity by identifying the most important features in the dataset. They then determined which features or combination of features had the largest contribution to the output — in other words, which physical parameters most strongly determined the geoeffectiveness of the event.

Ye and collaborators found that the strongest determinants of an event’s geoeffectiveness were how long the solar wind was directed southward, the strength of the solar wind electric field, and the average and minimum strengths of the southward-pointing solar wind magnetic field. These results align with the current understanding of how energy is transferred from the solar wind to Earth’s magnetosphere through magnetic reconnection, a release of magnetic energy driven by rearrangement of magnetic fields. This shows how classical machine learning methods can enhance our ability to predict the outcome of oncoming space weather while simultaneously examining the physical drivers of the event.

Citation

“Assessing the Geoeffectiveness of Stream Interaction Regions Through Physically Interpretable Machine Learning,” Yudong Ye et al 2025 ApJ 993 10. doi:10.3847/1538-4357/ae0454

The post When Winds Collide: Predicting the Effects of Stream Interaction Regions appeared first on AAS Nova.

Editor’s Note: For the remainder of 2025, we’ll be looking at a few selections that we haven’t yet discussed on AAS Nova from among the most-downloaded articles published in AAS journals this year. The usual posting schedule will resume January 2nd.

The Sun Reversed Its Decades-Long Weakening Trend in 2008

Published September 2025

Main takeaway:

Jamie Jasinski (NASA’s Jet Propulsion Laboratory) and Marco Velli (NASA’s Jet Propulsion Laboratory and the University of California, Los Angeles) analyzed solar wind data from 2008 to 2025 and found that many solar wind parameters such as speed, density, temperature, and magnetic field strength increased over that time period. This increase ran counter to expectations that the Sun may be entering a historically low period of activity in 2008.

Why it’s interesting:

The Sun undergoes an 11-year activity cycle that is driven by a change in its internal magnetic field structure. As the Sun’s magnetic activity changes, the number of sunspots, the frequency of solar flares and coronal mass ejections, and the intensity of the solar wind vary as well. Atop these mostly regular 11-year changes are longer-term variations. A recent example of this longer-term behavior began in the 1980s, when an overall weakening trend was stamped upon the usual 11-year cycle. This decline led to an exceptionally deep solar minimum in 2008, leading researchers to suspect that the Sun’s activity level might remain low for decades.

The historical context for a prolonged weak period:

Though the Sun reversed its weakening activity trend in 2008, a prolonged period with little solar activity wouldn’t have been unprecedented. Astronomers have monitored and counted sunspots for centuries, allowing modern-day researchers to investigate the Sun’s behavior long before spacecraft began to study our home star. In the historical record, there are two instances of weak solar activity spanning multiple decades: the Maunder minimum in 1645–1715 and the Dalton minimum in 1790–1830. Compared to the 11-year solar cycle, these longer-term behaviors are more difficult to predict, and their causes are uncertain.

Citation

Jamie M. Jasinski and Marco Velli 2025 ApJL 990 L55. doi:10.3847/2041-8213/adf3a6

The post Selections from 2025: The Sun Changed Course in 2008 appeared first on AAS Nova.