Space & Physics
In search for red aurorae in ancient Japan
Ryuho Kataoka, a Japanese auroral scientist, played a seminal role in searching for evidence of super-geomagnetic storms in the past using historical methods
Aurorae seen on Earth are the end of a complex process that begins with a violent, dynamic process deep within the sun’s interior.
However, studying the depths of the sun is no easy task, even for scientists. The best they can do is to observe the surface using space-based telescopes. One problem that scientists are attempting to solve is how a super-geomagnetic storm on Earth comes to being. These geomagnetic storms find their roots in sunspots, that are acne-like depressions on the sun’s surface. As the sun approaches the peak of its 11-year solar cycle, these sunspots, numbering in the hundreds, occasionally release all that stored magnetic energy into deep space, in the form of coronal mass ejections (CMEs) (which are hot wisps of gas superheated to thousands of degrees).
Super-geomagnetic storms, a particularly worse form of geomagnetic storm, can induce power surges in our infrastructure, causing power outages that can plunge the world into darkness, and can cause irreversible damages to our infrastructure
If the earth lies in the path of an oncoming CME, the energy release from their resultant magnetic field alignment can cause intense geomagnetic storms and aurorae on Earth.
This phenomenon, which is astrophysical and also electromagnetic in nature, can have serious repercussions for our modern technological society.
Super-geomagnetic storms, a particularly worse form of geomagnetic storm, can induce power surges in our infrastructure, causing power outages that can plunge the world into darkness, and can cause irreversible damages to our infrastructure. The last recorded super-geomagnetic storm event occurred more than 150 years ago. Known as the Carrington event, the storm destroyed telegraph lines across North America and Europe in 1859. The risk for a Carrington-class event to happen again was estimated to be 1 in 500-years, which is quite low, but based on limited data. Ramifications are extremely dangerous if it were to ever happen.
However, in the past decade, it was learnt that such super-geomagnetic storms are much more common than scientists had figured. To top it all, it wasn’t just science, but it was a valuable contribution by art – specifically ancient Japanese and Chinese historical records that shaped our modern understanding of super-geomagnetic storms.
Ryuho Kataoka, a Japanese space physicist, played a seminal role in searching for evidence of super-geomagnetic storms in the past using historical methods. He is presently an associate professor in physics, holding positions at Japan’s National Institute of Polar Research, and The Graduate University for Advanced Studies.
“There is no modern digital dataset to identify extreme space weather events, particularly super-geomagnetic storms,” said Professor Kataoka. “If you have good enough data, we can input them into supercomputers to do physics-based simulation.”
However, sunspot records go until the late 18th century when sunspots were actively being cataloged. In an effort to fill the data gap, Professor Kataoka decided to be at the helm of a very new but promising interdisciplinary field combining the arts with space physics. “The data is limited by at least 50 years,” said Professor Kataoka. “So we decided to search for these red vapor events in Japanese history, and see the occurrence patterns … and if we are lucky enough, we can see detailed features in these lights, pictures or drawings.” Until the summer of 2015, Ryuho Kataoka wasn’t aware of how vast ancient Japanese and Chinese history records really were.
“There is no modern digital dataset to identify extreme space weather events, particularly super-geomagnetic storms,” said Professor Kataoka.
In the past 7 years, he’s researched a very specific red aurora, in documents extending to more than 1400 years. “Usually, auroras are known for their green colors – but during the geomagnetic storm, the situation is very different,” he said. “Red is of course unusual, but we can only see red during a powerful geomagnetic storm, especially in lower latitudes. From a scientific perspective, it’s a very reasonable way to search for red signs in historical documents.”
A vast part of these historical red aurora studies that Professor Kataoka researched came from literature explored in the last decade by the AURORA-4D collaboration. “The project title included “4D”, because we wanted to access records dating back 400 years back during the Edo period,” said Professor Kataoka.
“From the paintings, we can identify the latitude of the aurora, and calculate the magnitude or amplitude of the geomagnetic storm.” Clearly, paintings in the Edo period influenced Professor Kataoka’s line of research, for a copy of the fan-shaped red aurora painting from the manuscript Seikai (which translates to ‘stars’) hangs on the window behind his office desk at the National Institute of Polar Research.
The painting fascinated Professor Kataoka, since it depicted an aurora that originated during a super-geomagnetic storm over Kyoto in 1770. However, the painting did surprise him at first, since he wondered whether the radial patterns in the painting were real, or a mere artistic touch to make it look fierier. “That painting was special because this was the most detailed painting preserved in Japan,” remarked Professor Kataoka. “I took two years to study this, thinking this appearance was silly as an aurorae scientist. But when I calculated the field pattern from Kyoto towards the North, it was actually correct!”
Fan-shaped red aurora painting from the ‘Seikai’, dated 17th September, 1770; Picture Courtesy: Matsusaka City, Mie Prefecture.
The possibility to examine and verify historical accounts using science is also a useful incentive for scholars of Japanese literature and scientists partaking in the research.
“This is important because, if we scientists look at the real National Treasure with our eyes, we really know these sightings recorded were real,” said Professor Kataoka. “The internet is really bad for a survey because it can easily be very fake,” he said laughing. It’s not just the nature in which science was used to examine art – to examine Japanese “national treasures” that is undoubtedly appealing, but historical accounts themselves have contributed to scientific research directly.
“From our studies, we can say that the Carrington class events are more frequent than we previously expected,” said Professor Kataoka. There was a sense of pride in him as he said this. “This Carrington event is not a 1 in 200-year event, but as frequent as 1 in 100 years.” Given how electricity is the lifeblood of the 21st century, these heightened odds do ingrain a rather dystopian society in the future, that is ravaged by a super-geomagnetic storm.
Professor Kataoka’s work has found attention within the space physics community. Jonathon Eastwood, Professor of Physics at Imperial College London said to EdPublica, “The idea to use historical information and art like this is very inventive because these events are so rare and so don’t exist as information in the standard scientific record.”
There’s no physical harm from a geomagnetic storm, but the threat to global power supply and electronics is being increasingly recognized by world governments. The UK, for instance, identified “space weather” as a natural hazard in its 2011 National Risk Register. In the years that followed, the government set up a space weather division in the Met Office, the UK’s foremost weather forecasting authority, to monitor and track occurrences of these coronal mass ejections. However, these forecasts, which often supplement American predictions – namely the National Oceanic and Atmospheric Administration (NOAA) – have failed to specify previously where a magnetic storm could brew on Earth, or predict whether a coronal mass ejection would ever actually strike the Earth.
Professor Kataoka said he wishes space physicists from other countries participate in similar interdisciplinary collaborations to explore their native culture’s historical records for red aurora sightings
The former occurred during the evacuation process for Hurricane Irma in 2017, when amateur radio ham operators experienced the effects of a radio blackout when a magnetic storm affected the communications network across the Caribbean. The latter occurred on another occasion when a rocket launch for SpaceX’s Starlink communication satellites was disrupted by a mild geomagnetic storm, costing SpaceX a loss of over $40 million.
Professor Kataoka said he wishes space physicists from other countries participate in similar interdisciplinary collaborations to explore their native culture’s historical records for red aurora sightings. He said the greatest limitation of the AURORA-4D collaboration was the lack of historical records from other parts of the world. China apparently boasts a history of aurora records longer than Japan, with a history lasting before Christ himself. “Being Japanese, I’m not familiar with British, Finnish or Vietnamese cultures,” said Professor Kataoka. “But every country has literature researchers and scientists who can easily collaborate and perform interdisciplinary research.” And by doing so, it’s not just science which benefits from it, but so is ancient art whose beauty and relevance gains longevity.
Space & Physics
Indian-Belgian Team Develops Portable Detectors to Image Mountains and Monuments Using Cosmic Rays
Portable cosmic-ray detectors could help researchers examine mountains, tunnels and historical monuments without invasive procedures, opening new possibilities for scientific imaging and infrastructure inspection.
An international team of researchers from India and Belgium has developed portable particle detectors that could help scientists examine the interiors of mountains, tunnels and historical monuments without damaging them. The technology uses naturally occurring cosmic-ray particles to map variations in the density of objects, offering a potential approach to non-invasive imaging of large structures.
The detectors, developed using glass-based Resistive Plate Chambers (RPCs), achieved a particle-detection efficiency exceeding 95% during testing, according to a report published by Research Matters on October 24, 2026. The findings demonstrate the potential of compact detector systems to investigate dense materials and support future applications in geology, archaeology and infrastructure assessment.
The collaboration includes researchers from India’s National Institute of Science Education and Research (NISER), Bhubaneswar, and the Homi Bhabha National Institute (HBNI), alongside researchers from Belgian institutions, including Université catholique de Louvain and the Inter-University Institute for High Energies.
How cosmic rays reveal hidden structures
The technology uses muons, high-energy particles produced when cosmic rays interact with Earth’s atmosphere. These particles continuously reach the Earth’s surface and can penetrate substantial thicknesses of rock, concrete and other materials.
As muons travel through an object, some are absorbed or deflected depending on its density and thickness. By measuring the number and trajectories of particles passing through a structure, researchers can identify variations in internal density and reconstruct images of otherwise inaccessible areas.
The technique, known as muography, is comparable in principle to X-ray imaging, but uses naturally occurring particles instead of an artificial radiation source. It has previously been used to investigate geological formations, including volcanoes, and to explore archaeological structures.
However, conventional muon detectors can be bulky, difficult to transport and challenging to operate in remote locations. The new glass-based detectors aim to address some of these limitations through a compact design and sealed operation, reducing dependence on continuous gas supplies.
Testing the detector system
The researchers developed three glass RPC prototypes using thin glass electrodes separated by gas-filled gaps. When a muon passes through a chamber, it ionises the gas, generating an electrical signal that can be recorded to determine the particle’s position.
Electronic readout systems capture these signals and help reconstruct the trajectories of incoming particles. During testing, the detectors achieved an efficiency exceeding 95%, with a timing resolution of approximately 1.8 nanoseconds, according to the research report.
To examine the system’s ability to detect dense materials, the team conducted an absorption experiment using one prototype. During an open-sky measurement, researchers recorded nearly 55,000 muon tracks. After placing a lead block in the experimental setup, the recorded count fell to 30,894, demonstrating how dense material reduced the number of particles reaching the detector.
Representational image.Image credit:Pexels
The experiment provided proof of principle that the system could measure muon attenuation and support radiographic imaging. However, imaging complex structures such as mountains or monuments requires measurements from multiple directions and further computational reconstruction.
Applications and challenges ahead
Portable muon detectors could eventually help researchers investigate hidden cavities, examine geological formations, inspect tunnels and study the internal structures of historical monuments. Engineers could also explore their application in assessing infrastructure such as dams and bridges, although these uses would require additional testing and validation.
For cultural heritage conservation, muography could offer a valuable alternative where drilling or other invasive investigations risk damaging fragile structures. A 2025 review published in iScience highlighted the technique’s potential as a complementary, non-destructive method for studying cultural heritage objects, while noting that the relatively low flux of naturally occurring muons can require lengthy data-collection periods.
The technology is not yet a universal replacement for existing inspection methods. Its practical application will depend on factors such as spatial resolution, detector size, measurement duration and the complexity of the structure being examined.
The researchers have proposed further improvements, including lighter structural materials, larger detector areas and enhanced readout systems. These developments could make the detectors easier to deploy and improve the quality of reconstructed images.
Space & Physics
How Scientists Traced the Flow of Matter Around a Dead Star Using X-rays
By studying changes in X-ray signals from Centaurus X-3, researchers at Bengaluru’s Raman Research Institute have found evidence of an unusual way in which matter reaches a neutron star. The discovery could change how scientists explain the radiation coming from this distant system.
When a massive star dies, its core can collapse into an extremely dense object called a neutron star. Despite being only about the size of a city, it can have a mass comparable to that of the Sun. Its powerful gravity can pull matter away from a nearby companion star, releasing energy in the form of X-rays as the material falls towards it.
Scientists at Bengaluru’s Raman Research Institute (RRI) have studied these X-ray signals from Centaurus X-3, a star system about 24,000 light-years from Earth. By examining changes in the signals, the researchers identified a stream of matter flowing towards the neutron star and found evidence of a rotating disk of material around it. This is an unusual finding because such disks are not commonly expected in this type of star system. The discovery could help scientists better understand how matter moves around neutron stars and how these distant objects produce X-rays.
Star That Pulls in Matter
Centaurus X-3 is in the constellation Centaurus. It belongs to a class of systems known as high-mass X-ray binaries. These systems contain a neutron star and a massive companion star held together by gravity.
A neutron star forms when the core of a massive star collapses at the end of its life. It packs roughly the Sun’s mass into a sphere only about the size of a city. Its gravity is so strong that it can pull in material from a nearby companion star. As this material falls towards the neutron star, it releases enormous amounts of energy, including X-rays. Scientists study this radiation to understand how the material behaves and how the system works.
Centaurus X-3 is also a pulsar. Its neutron star rotates and sends out radiation from regions near its magnetic poles. As the star spins, these beams sweep across space. When a beam passes an observing satellite, the satellite detects a pulse of radiation, much as a lighthouse produces a repeating flash as it turns. These regular pulses provide scientists with a way to study the neutron star and its surroundings.
What the Changing Signals Revealed
The radiation from Centaurus X-3 does not come only from the neutron star itself. Some of it interacts with nearby material, including the surface of the companion star, gas flowing away from it and matter surrounding the neutron star. This material absorbs radiation and emits it again. Scientists call this secondary radiation.
Changes in this radiation can help researchers work out what is happening around the neutron star. However, Centaurus X-3 is so far away that telescopes cannot clearly distinguish its surrounding structures. It appears as a single point of light. Scientists must therefore piece together the system’s structure from the signals they receive.
Earlier observations had shown that the intensity of certain secondary X-ray emission lines changed as the neutron star rotated. An emission line is a feature in a spectrum that can reveal information about the material producing or interacting with the radiation. A research team led by Kinjal Roy of RRI examined four such emission lines in detail. The researchers found that the structure producing these changes must be rotating along with the neutron star.
The pattern helped them identify the likely source which is a stream of matter moving towards the neutron star.
Following the stream of matter
This stream is part of a process called accretion, in which a compact object draws in material from its surroundings. In Centaurus X-3, the stream carries matter from an accretion disk towards the neutron star. The disk is a rotating structure of gas and other material that moves around the star before being drawn inwards. The neutron star’s magnetic field then guides the incoming matter towards its magnetic poles.
The stream also changes what an observing satellite sees. As it moves around the neutron star, it can come between the satellite and the star, partially blocking the direct radiation. When this happens, the primary X-ray signal weakens. At the same time, radiation from the stream itself becomes stronger in the observed signal.
The researchers used these changing signals to connect the observed variations to the movement of matter around the neutron star. The evidence for an accretion stream also points to an accretion disk feeding it. This matters because scientists generally expect high-mass X-ray binaries to gather material in a different way.
Why an accretion disk matters
In many high-mass X-ray binaries, a neutron star captures gas directly from the stream of material blown away by its companion star. This is known as stellar-wind accretion. An accretion disk involves a different arrangement: material gathers into a rotating structure before flowing towards the neutron star. The findings from Centaurus X-3 indicate that this disk-based process is taking place in a system where it is not generally expected.
That difference matters when scientists calculate how the system produces and releases radiation. If their models leave out the disk, they may fail to account for some of the radiation coming from the surrounding material.
“Accretion disk is not expected to occur in [HMXBs] So, if an accretion disk is forming in this system, emission models have to be modified,” Roy said in the Department of Science and Technology’s announcement. He added that future models of Centaurus X-3 would need to account for radiation from the disk.
The research does not mean that scientists have directly photographed the disk. Instead, they have used the changing X-ray signals to infer the presence and behaviour of structures that remain too distant to resolve clearly. Published in The Astrophysical Journal, the study adds to the understanding of Centaurus X-3, one of the most widely studied binary pulsars. It also shows how small changes in radiation can reveal the movement of matter around objects that are otherwise beyond the reach of direct observation.
By identifying the flow responsible for the changing signals, the researchers have provided a more detailed picture of how this neutron star draws in material. That picture will help scientists refine their models of Centaurus X-3 and examine whether similar processes occur in other high-mass X-ray binaries.
Space & Physics
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