How superstorm Gannon squeezed Earth’s plasmasphere to one-fifth its size

New study shows how a major space storm dramatically shrank Earth’s protective plasma layer and slowed its recovery, helping improve solar storm forecasts and protect space infrastructure we rely on.

Nagoya University

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Scientists have captured the first detailed observations of how a superstorm compresses Earth’s plasmasphere and reveal why recovery took more than four days, affecting navigation and communication systems.

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Credit: Institute for Space-Earth Environmental Research (ISEE), Nagoya University

A geomagnetic superstorm is an extreme space weather event that occurs when the Sun releases massive amounts of energy and charged particles toward Earth. These storms are rare, occurring about once every 20-25 years. On May 10-11, 2024, the strongest superstorm in over 20 years, known as the Gannon storm or Mother’s Day storm, struck Earth.  

A study led by Dr. Atsuki Shinbori from Nagoya University's Institute for Space-Earth Environmental Research has captured direct measurements of this extreme event and provided the first detailed observations of how a superstorm compresses Earth's plasmasphere—a protective layer of charged particles that encircles our planet. Published in Earth, Planets and Space, the findings show how the plasmasphere and ionosphere react during the most violent solar storms and help forecast disruptions to satellites, GPS systems, and communication networks during extreme space weather events. 

Right place, right time: How Arase captured historic data 

Launched by the Japan Aerospace Exploration Agency (JAXA) in 2016, the Arase satellite orbits through Earth's plasmasphere measuring plasma waves and magnetic fields. During the May 2024 superstorm, it was positioned perfectly to observe the extreme compression and slow recovery of the plasmasphere in unprecedented detail. This was the first time scientists obtained continuous, direct measurements of the plasmasphere shrinking to such a low altitude during a superstorm. 

“We tracked changes in the plasmasphere using the Arase satellite and used ground-based GPS receivers to monitor the ionosphere—the source of charged particles that refill the plasmasphere. Monitoring both layers showed us how dramatically the plasmasphere contracted and why recovery took so long,” Dr. Shinbori explained. 

The plasmasphere works with Earth’s magnetic field to help limit harmful charged particles from the Sun and space, protecting satellites and supporting Earth’s natural shielding system against intense radiation. It normally extends far from Earth, but during the superstorm the outer boundary moved from approximately 44,000 km above Earth's surface to just 9,600 km. 

The superstorm was triggered by many massive eruptions from the Sun that hurled billions of tons of charged particles toward Earth. Within nine hours, the storm squeezed the plasmasphere to about one-fifth of its normal size. Recovery was very slow and took more than four days to refill, the longest recovery scientists have seen since they started monitoring the plasmasphere with the Arase satellite in 2017. 

“We found that the storm first caused intense heating near the poles, but later this led to a big drop in charged particles across the ionosphere, which slowed recovery. This prolonged disruption can affect GPS accuracy, interfere with satellite operations, and complicate space weather forecasting,” Dr. Shinbori noted. 

Visual evidence: Storm pushes auroras further to the equator 

During the most intense phase of the superstorm, extreme solar activity compressed Earth’s magnetic field, allowing charged particles to travel much farther along magnetic field lines toward the equator. This produced impressive auroras at unusually low latitudes.  

Auroras typically occur near the polar regions because Earth’s magnetic field guides solar particles into the atmosphere there, but the strength of this storm shifted the auroral zone from its usual position near the Arctic and Antarctic circles down to mid-latitude regions such as Japan, Mexico, and southern Europe—places where auroras are rarely seen. The stronger the geomagnetic storm, the farther toward the equator auroras can appear. 

Impact of negative storms on plasmasphere recovery 

About an hour after the storm struck, charged particles in Earth’s upper atmosphere surged at high latitudes near the poles and streamed toward the polar cap. When the storm began to subside the plasmasphere started to refill with particles from the ionosphere.  

Normally, this process takes a day or two, but in this case recovery stretched over four days because of a phenomenon called a negative storm. During a negative storm, particle levels in the ionosphere drop sharply across wide areas when intense heating changes the atmosphere’s chemistry. This decreases oxygen ions that help produce hydrogen particles needed to refill the plasmasphere. These storms are invisible and detected only by satellites. 

“The negative storm slowed recovery by altering atmospheric chemistry and cutting off the supply of particles to the plasmasphere. This link between negative storms and delayed recovery had never been clearly observed before,” Dr. Shinbori said. 

The findings give us a clearer picture of how the plasmasphere changes and how energy moves through it. During the storm, several satellites experienced electrical issues or stopped transmitting data, GPS signals were disrupted, and radio communications were affected. Knowing how long Earth’s plasma layer takes to recover after such events is key for forecasting space weather and safeguarding space technology.

A rare low-latitude aurora photographed at Rikubetsu, Japan, during the May 2024 super geomagnetic storm, the strongest in over 20 years. This storm caused extreme compression of Earth’s plasmasphere, documented for the first time through direct satellite measurements.

Credit

Nozomu Nishitani, Institute for Space-Earth Environmental Research (ISEE), Nagoya University

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Journal

Earth Planets and Space

DOI

10.1186/s40623-025-02317-3 

Subject of Research

Not applicable

Article Title

Characteristics of temporal and spatial variation of the electron density in the plasmasphere and ionosphere during the May 2024 super geomagnetic storm

Article Publication Date

20-Nov-2025

 

Use of head CT scans in ERs more than doubles over 15 years

American Academy of Neurology

 

MINNEAPOLIS — A new study shows large increases in the use of computed tomography (CT) scans of the head in emergency departments across the United States from 2007 to 2022. The study, which was published on November 19, 2025, in Neurology®, the medical journal of the American Academy of Neurology, also found disparities in use of head CTs by race, type of insurance and hospital location. 

“Head CT scans are a critical tool for diagnosing neurological emergencies, but their growing use raises concerns about cost, radiation exposure and delays in the emergency department,” said study author Layne Dylla, MD, PhD, of Yale School of Medicine in New Haven, Connecticut. “It’s important to balance the benefits of these scans with the risks and costs.”

For some situations, CT scans are considered unnecessary, as guidelines have shown that the images add little value to diagnosis but bring additional costs and radiation exposure. However, in other situations, CT scans are critical for time-sensitive diagnoses and treatments.

The study looked at a national hospital database, with results weighted to provide national estimates. In 2007, 7.84 million head CT scans were performed in emergency departments across the country. By 2022, that number had more than doubled to 15.98 million scans. This was an increase from head CTs done in 6.7% of all emergency department visits to 10.3%.

After adjusting for other factors that could affect the use of CT scans, such as age and the reason people went to the hospital, researchers found that Black people were 10% less likely to receive a head CT scan than white people. People who were on Medicaid insurance were 18% less likely to receive a head CT scan than those who were on Medicare or private insurance. People who received care in a rural hospital were 24% less likely to receive a head CT scan than those in urban areas.

People 65 years old and older were six times more likely to receive a head CT scan than people younger than 18 years old.

“Overall, these results highlight the need for more equitable access to neuroimaging in emergency care and further evaluation of the appropriateness of every head CT according to clinical recommendations,” Dylla said. “It’s important to recognize the tension between underuse of scans, leading to missed diagnosis, and overuse, resulting in radiation exposure and additional financial and patient care strains on the health care system.”

A limitation of the study is that the database does not include detailed information such as the patient’s medical history and how long they have had symptoms and how severe the symptoms are, making it challenging to determine whether the head CT scan was medically appropriate, according to Dylla.

Discover more about brain health at Brain & Life®, from the American Academy of Neurology. This resource also offers a website, podcast, and books that connect patients, caregivers and anyone interested in brain health with the most trusted information, straight from the world’s leading experts in brain health. Follow Brain & Life® on Facebook, X, and Instagram.

The American Academy of Neurology is the leading voice in brain health. As the world’s largest association of neurologists and neuroscience professionals with more than 40,000 members, the AAN provides access to the latest news, science and research affecting neurology for patients, caregivers, physicians and professionals alike. The AAN’s mission is to enhance member career fulfillment and promote brain health for all. A neurologist is a doctor who specializes in the diagnosis, care and treatment of brain, spinal cord and nervous system diseases such as Alzheimer's disease, stroke, concussion, epilepsy, Parkinson's disease, multiple sclerosis, headache and migraine.

Explore the latest in neurological disease and brain health, from the minds at the AAN at AAN.com or find us on Facebook, X, Instagram, LinkedIn, and YouTube.

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Journal

Neurology

Center for Open Science awarded grant from Robert Wood Johnson Foundation to preserve and safeguard publicly funded scientific data

Center for Open Science

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The Center for Open Science (COS) has been awarded a grant from the Robert Wood Johnson Foundation (RWJF) to develop a community-driven strategic plan for ensuring the long-term preservation, accessibility, and usability of federally-funded scientific data.

COS has long championed policies and practices that increase the openness, integrity, and trustworthiness of research. The success of the open science movement relies on the integrity, sustainability, and resilience of infrastructures that promote access to research outputs, like scientific data. In 2025, the sudden removal of public data from multiple federal agency websites underscored the urgent need for sustainable systems to safeguard and maintain public access to scientific data generated by federally funded researchers.

The RWJF-funded project, Ensuring the Preservation, Accessibility, and Usability of Public Data, will be led by COS, with co-direction from a stakeholder planning committee composed of leaders from across the research and scientific data communities.

Planning committee members are Maria Gould (DataCite), Joel Gurin (CODE), Robert Hanisch (Campostella Research and Consulting), Kristi Holmes (Northwestern University), Lynda Kellam (University of Pennsylvania, Data Rescue Project), Christine Kirkpatrick (San Diego Supercomputer Center, UC San Diego, GO FAIR US), Chris Marcum (Data Foundation), Mark Parsons (ESIP), and Katherine Skinner (IOI). Alex Wade is serving as the project’s lead consultant.

The project aims to complement and coordinate with existing community-driven initiatives—including the Internet Archive, the Inter-university Consortium for Political and Social Research (ICPSR), and the Data Rescue Project—by developing a framework for long-term stewardship of federally-funded data. The resulting strategic plan will guide how the research community monitors, preserves, and sustains access to at-risk datasets and repositories.

Areas for initial focus and exploration include:

• Monitoring at-risk repositories: Clarifying methods for identifying repositories that may face data loss due to funding, staffing, or policy changes.
• Ensuring FAIRness and resilience of preserved datasets: Establishing processes and building capacity to promote the FAIRness (findability, accessibility, interoperability, and reusability) and resilience of preserved datasets and associated tools to support their continued discoverability and use in a distributed data ecosystem.
• Dashboard for data health: Creating a shared framework to inform decision making that data stewards and communities can use to score and monitor data health across multiple dimensions, including preservation, resilience, FAIRness, usability and utility for different audiences, and availability of interactive tools.
• Building governance and sustainability: Outlining models for coordinated community action, avoiding duplication of effort, defining best practices for preservation, and ensuring sustained stewardship of preserved data.
• Developing an outreach and advocacy framework: Raising awareness and catalyzing action among researchers, funders, policymakers, and the broader public about the importance and vulnerability of public data and associated infrastructures, including guidance on accessing preserved datasets, reporting at-risk resources, and ways to support and advocate for more sustainable and resilient infrastructures.

“Together with our expert strategic planning partners, COS is committed to meeting the moment to promote the resilience of the scientific data system. We’re looking forward to continuing to build on the great progress we’ve made to promote greater openness, transparency, and integrity to ensure science continues to serve the public good,” said project co-lead Maryam Zaringhalam, PhD, COS Senior Director of Policy.

The project will run through September 2026. Insights generated during the planning process will also inform COS’s own data infrastructure work through the Open Science Framework (OSF) and related advocacy efforts that support transparency and sustainable data management.

For more information about the project or to get involved, visit the Ensuring the Preservation, Accessibility, and Usability of Public Data webpage.

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About COS
Founded in 2013, COS is a nonprofit culture change organization with a mission to increase openness, integrity, and reproducibility of scientific research. COS pursues this mission by building communities around open science practices, supporting metascience research, and developing and maintaining free, open source software tools, including the Open Science Framework (OSF).

 

Trapping particles to explain lightning

ISTA scientist captures tiny particles for clues on cloud electrification

Institute of Science and Technology Austria

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A green spectacle. With protective eyewear, ISTA PHD student Andrea Stöllner takes a glimpse into the experimental chamber (in the foreground) where two laser beams trap a single particle. One electron at a time, the scientist hopes that her work will reveal mysteries about how tiny particles behave and advance the scientific inquiry into cloud electrification. As the green glow of the captured particle dims, Stöllner promptly restarts her setup to catch another one. 

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Credit: © ISTA

Using lasers as tweezers to understand cloud electrification might sound like science fiction but at the Institute of Science and Technology Austria (ISTA) it is a reality. By trapping and charging micron-sized particles with lasers, researchers can now observe their charging and discharging dynamics over time. This method, published in Physical Review Letters, could provide key insights into what sparks lightning.

Aerosols are liquid or solid particles that float in the air. They are all around us. Some are large and visible, such as pollen in spring, while others, such as viruses that spread during flu season, cannot be detected by the naked eye. Some we can even taste, like the airborne salt crystals we breathe in at the seaside. 

PhD student Andrea Stöllner, part of the Waitukaitis and Muller groups at the Institute of Science and Technology Austria (ISTA), focuses on ice crystals within clouds. The Austrian scientist uses model aerosols—tiny, transparent silica particles—to explore how these ice crystals accumulate and interact with electrical charge.

Stöllner, alongside former ISTA postdoc Isaac Lenton, ISTA Assistant Professor Scott Waitukaitis and others, has developed a way to catch, hold, and electrically charge a single silica particle using two laser beams. This approach holds potential for application in different areas, including demystifying how clouds become electrified and what sparks lightning.

Laser tweezers lock aerosol particle in place

Andrea Stöllner stands in front of a large desk covered with shiny metal gadgets. Green laser beams cut across the space, bouncing around through a series of small mirrors. A squishing sound comes from the table, like air escaping from a tire. “It’s an anti-vibration table,” Stöllner explains, noting its crucial role in absorbing any vibrations from the room and nearby equipment—essential for precision work with lasers.

The beams zigzag around a type of obstacle course, eventually converging into two streams that funnel into a container. Here, the two beams meet and create a ‘trap,’ where tiny objects are held steadily by light alone, acting as “optical tweezers.” Inside this magical box, particles drift past these tweezers. Suddenly, boom! A green flash appears, signaling success: A perfectly round, vibrant green glowing aerosol particle has been caught and is being held tightly by the tweezers.

“The first time I caught a particle, I was over the moon,” Stöllner says as she recalls her Eureka moment two years ago, just before Christmas. “Scott Waitukaitis and my colleagues rushed into the lab and took a short glimpse at the captured aerosol particle. It lasted exactly three minutes, then the particle was gone. Now we can hold it in that position for weeks.”

It took Stöllner almost four years to get the experiment to the point where it could provide reliable data, starting with a previous version of the setup developed by her former ISTA colleague Lenton. “Originally, our setup was built to just hold a single particle, analyze its charge, and figure out how humidity changes its charges,” explains Stöllner. “But we never came this far. We found out that the laser we are using is itself charging our aerosol particles.”

Kicking out electrons

The scientist and her colleagues discovered that lasers charge the particle through a “two-photon process.”

Typically, aerosol particles are close to neutrally charged, with electrons (negatively charged entities) swirling around in every atom of the particle. The laser beams consist of photons (particles of light traveling at the speed of light), and when two of these photons are absorbed simultaneously, they can ‘kick out’ one electron from the particle. In this way, the particle gains one elemental positive charge. Step by step, it becomes increasingly positively charged.

For Stöllner, uncovering this mechanism is an exciting discovery that she can leverage in her research. “We can now precisely observe the evolution of one aerosol particle as it charges up from neutral to highly charged and adjust the laser power to control the rate.”

This observation also reveals that, as the particle becomes positively charged, it begins to discharge, meaning that it occasionally releases charge in spontaneous bursts.

Way above our heads, something similar might also be happening in clouds. 

Lifting the lid on lightning?

Thunderstorm clouds contain ice crystals and larger ice pellets. When these collide, they exchange electric charges. Eventually, the cloud becomes so charged that lightning forms. One theory suggests that the first little spark of a lightning bolt could be initiated at the charged ice crystals themselves. However, the exact science behind the phenomenon of lightning formation remains a mystery. Alternative theories meanwhile suggest cosmic rays initiate the process as the charged particles they create accelerate from pre-existing electric fields. According to Stöllner, however, the current understanding in the scientific community is that – in either case – the electric field in clouds seems too low to cause lightning.

“Our new setup allows us to explore the ice crystal theory by closely examining a particle’s charging dynamics over time,” Stöllner explains. While ice crystals in clouds are much larger than the model ones, the ISTA scientists are now aiming to decode these microscale interactions to better understand the big picture. “Our model ice crystals are showing discharges and maybe there’s more to that. Imagine if they eventually create super tiny lightning sparks—that would be so cool,” Stöllner says with a smile. 

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Journal

Physical Review Letters

DOI

10.1103/5xd9-4tjj 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Using optical tweezers to simultaneously trap, charge and measure the charge of a microparticle in air

Article Publication Date

20-Nov-2025

Video: Catching a particle [VIDEO] 

Catching a particle. Thousands of tiny model aerosols pass through optical tweezers when suddenly, boom! One particle becomes trapped. The aerosol particle is glowing green as it scatters the laser light. 

Credit

© Andrea Stöllner / ISTA

  

Adjusting the experimental setup. Andrea Stöllner fine-tunes the orientation of laser beams, mirrors, and cameras on an anti-vibration table. 

ISTA PhD student Andrea Stöllner in front of her experimental setup. Beyond the lab, the physicist and “cloud scientist” finds relaxation in yoga, baking, and playing the flute in an orchestra. Lately, she cannot get the dramatic symphonic poem “The Witch and the Saint” out of her head. 

Sketch of the experimental setup. The trapping laser (532 nm) is split into two beams by a polarizing beam splitter and coupled into single-mode optical fibers. The beams eventually enter the grounded experimental chamber through one-inch windows on either side. Inside, they are focused by two lenses with a focal length of 8 mm to form a one-micrometer trap.

Credit

© Stoellner et al. / Physical Review Letters

Optical Trap. Catching a micron-sized particle is challenging. To get the job done, two laser beams come in handy. Acting like tweezers, they can trap, secure, and charge a solitary particle. 

Credit

© Andrea Stöllner / ISTA