The reconstruction rests on 23 auroral records within China for 11–19 September 1770, drawn from regional chronicles, official Qing historical compendia, and modern collections of ancient Chinese astronomical records. The survey covered longitudes from 73° to 135° E and latitudes from 18° to 54° N, with particular attention to southern provinces. European and American reports were added from the NASA Space Physics Data Facility historical aurora database, while Japanese and Korean observations came from an existing compilation. The southernmost Chinese account came from Dongtinghu in Hunan Province, at 29.14° N and 113.12° E. It described red vapor, hundreds of emerald-white rays, and a fiery display that illuminated the sky before fading at dawn.

Because the auroral oval is organized by magnetic rather than geographic coordinates, the investigators converted each location using the GUFM1 historical geomagnetic field model to locate the 1770 magnetic north pole, then transformed the coordinates with the AACGM-v2 algorithm, which includes non-dipolar field contributions. The historical account at Dongtinghu indicated a display extending to high elevation, but did not supply a numerical viewing angle. The researchers therefore selected a conservative elevation of 60° rather than the zenith value of 90°. This choice places the inferred equatorward auroral boundary farther poleward and yields a less intense storm estimate. Based on the viewing geometry, the boundary was placed at 20.40° N magnetic latitude at ionospheric altitude.

A nearly conjugate Southern Hemisphere observation provides a second spatial constraint. Captain Cook’s crew aboard HMS Endeavour reported an aurora near the Malacca Strait Narrows, at 10.45° S and 112.82° E, corresponding to a ground magnetic latitude of 20.39° S. Its viewing geometry implied an auroral boundary at 28.23° S. The less-than-40-degree separation between the northern and southern signatures was interpreted as evidence that the magnetosphere was severely compressed and eroded. This does not by itself establish storm intensity, but it is consistent with the extraordinary low-latitude visibility documented in East Asia. European reports for 1770 were comparatively sparse and concentrated in Germany and France, while Japan recorded the aurora as a major spectacle.

To translate auroral extent into an index of geomagnetic severity, the authors used a nonlinear least-squares relationship between the magnetic latitude of the auroral boundary and Dst. Their calibration contained 37 extreme storms from space-age and historical periods. Inverting that relationship produced the Qianlong XXXV estimate of −1,319 nT. Applying the identical procedure to auroral reports from the 1859 Carrington event yielded −1,025 nT, broadly consistent with earlier retrospective estimates of roughly −855 to −1,087 nT. The reconstructed Qianlong boundary was also farther equatorward than the Carrington boundary, which the method placed at 28.30° N. The study’s central comparison therefore favors a stronger 1770 disturbance, while the overlapping confidence intervals require a cautious interpretation.

The authors checked their framework against the May 2024 storm, for which direct measurements are available. Solar active region AR3664 produced several X-class flares and coronal mass ejections, followed by a G5-class geomagnetic storm with a peak Dst of −412 nT. The researchers considered unaided visual sightings while excluding observations detected only by sensitive cameras, thereby approximating the visibility conditions of the 18th century. A red aurora imaged at Hanle in Ladakh was classified as a stable auroral red arc, a phenomenon associated with ring-current energy dissipation rather than the active auroral oval. The southernmost accepted naked-eye report was from Alxa Youqi in Inner Mongolia, whose corresponding auroral boundary was estimated at 40.99° N magnetic latitude.

Historical reports present a major source of uncertainty because observers could not distinguish an active auroral oval from a stable auroral red arc. Such a misclassification could move a reconstructed Dst toward more negative values, especially because both phenomena can expand equatorward during extreme storms. The southernmost Qianlong XXXV report offers a partial safeguard: its emerald-green and white coloration is consistent with atomic oxygen emissions associated with the active auroral oval, whereas stable auroral red arcs are characteristically red. The authors consequently interpret the Qianlong estimate as a conservative lower bound on disturbance intensity. Other stated limitations include the selected viewing-angle assumption and the inability to retrieve the southward interplanetary magnetic field that controlled how efficiently the solar eruption coupled to Earth’s magnetosphere.

Applying a Gumbel extreme-value model to the reconstructed intensities, the researchers estimated a central recurrence interval of approximately 14,000 years for a storm matching Qianlong XXXV. The corresponding central estimate for Carrington-class storms was approximately 1,400 years. These are statistical return periods derived from a small set of historical extremes and a selected probability model, not observed waiting times or precise forecasts. The model’s assumptions limit how confidently it can describe the frequency of events beyond the instrumental era. Even so, the calculation illustrates how historical archives can extend the observational baseline for rare space weather and help constrain the tail of a storm-intensity distribution.

Sunspot evidence offers a possible explanation for the event’s exceptional scale. Historical records indicate a corrected area of about 6,000 millionths of the solar disk, roughly twice the size of the Carrington sunspot group, implying a large reservoir of magnetic energy. The active region was first observed near the eastern limb on 12 September and rotated toward, but not beyond, the central meridian during the storm’s peak, a geometry that could have directed coronal mass ejections toward Earth. The source also raises the possibility of investigating the event with annually resolved tree-ring carbon-14 records, whose continuous coverage now extends about 3,000 years. Such a multi-proxy approach could test whether a solar energetic-particle event accompanied the geomagnetic storm and tighten estimates derived from auroral observations.

The historical comparison also raises the role of Earth’s changing magnetic field. The dipole moment has weakened by approximately 14% since 1770 and by 7.4% since 1859, meaning that the 1770 magnetosphere began the storm under a stronger background field than the one present during Carrington. Under the study’s interpretation, reaching the same low magnetic-latitude auroral boundary in 1770 may have required a more powerful solar eruption than one capable of producing the 1859 disturbance. The result does not demonstrate that Carrington was the absolute upper limit of geomagnetic activity, and the authors do not treat the Qianlong central estimate as a replacement for direct measurement. Instead, the study presents a quantitative, archive-based candidate for a more extreme benchmark, while emphasizing the need for a larger catalog of historical storms, independent cosmogenic evidence, and physical modeling before either recurrence estimate can be used with high confidence.

Subject of Research: Archive-based reconstruction of the September 1770 Qianlong XXXV extreme geomagnetic storm

Article Title: The Qianlong XXXV event: a potential benchmark for extreme geomagnetic storms based on historical Chinese auroral archives

Article References: Yuan, D., Yin, T., Xu, X., Wang, B., Srivastava, A. K., Poedts, S., Nakariakov, V. M., Feng, X., Chen, W., & Luo, D. (2026). The Qianlong XXXV event: a potential benchmark for extreme geomagnetic storms based on historical Chinese auroral archives. Frontiers in Astronomy and Space Sciences, 13, Article 1857812. https://doi.org/10.3389/fspas.2026.1857812

Image Credits: AI Generated

DOI: 10.3389/fspas.2026.1857812

Keywords: Qianlong XXXV storm, geomagnetic superstorm, Chinese chronicles, auroral oval, Dst index, Carrington event, historical aurora, extreme space weather, Gumbel model, magnetic latitude, Qianlong, XXXV

The challenge in answering this question lies in the brevity of our observational record. The energy released by a solar flare can be measured directly only from outside Earth’s atmosphere, or determined indirectly from data and images gathered by space probes. Both approaches have been available only since the dawn of the space age roughly seventy years ago. In that entire period, the Sun has produced no superflare. Yet seventy years is a vanishingly small sliver of time for a star that has been burning for 4.6 billion years. As Natalie Krivova, an MPS scientist and lead author of the new study, explained, there is some evidence suggesting that the Sun, too, can produce superflares at great intervals, but there is no direct proof. The new research set out to close that evidentiary gap through an ingenious combination of modern solar observation and historical record-keeping stretching back centuries.

One line of evidence comes from the Sun’s stellar peers. Our galaxy contains many thousands of stars that resemble the Sun in key characteristics such as mass, temperature, and rotation rate. In late 2024, MPS researchers demonstrated that these Sun-like stars produce superflares approximately once every hundred years. If our star behaves like its counterparts, and there is good reason to think it might, then superflares should be a recurring, if rare, feature of solar activity. A second line of evidence comes from natural archives of solar history. Tree trunks preserved for millennia and ice cores extracted from the Arctic’s permafrost contain spikes in the concentrations of radioactive isotopes, isolated, short-lived, and exceptionally strong signals that suggest Earth has repeatedly been exposed to intense bombardment by high-energy solar particles in the distant past. These cosmogenic fingerprints are the only long-term traces such events leave behind, because a flare itself, no matter how powerful, leaves no lasting physical record on the Sun or in its immediate surroundings.

The relationship between these extreme particle eruptions and superflares remains an active area of investigation. According to Valeriy Vasilyev, an MPS scientist and lead author of a companion review article also published in Philosophical Transactions of the Royal Society A, the current state of research indicates that extreme particle eruptions and particularly intense flares often, but not always, occur together. This partial overlap means that isotope spikes in tree rings and ice cores are suggestive but not conclusive evidence of past superflares. What was needed was a way to connect the physics of flare production to measurable quantities that humans have been recording for far longer than the space age. The new study led by Krivova provides exactly that bridge, and it does so by exploiting one of the most carefully maintained observational datasets in all of science.

The first step of the analysis relied on modern instrumentation. The team examined observational data collected by NASA’s Solar Dynamics Observatory between 2010 and 2016, a period of intense solar monitoring during which the spacecraft continuously tracked the Sun’s surface, magnetic field, and atmosphere. From this dataset, the researchers identified the 300 strongest flares of the observation window and correlated the amount of energy each flare released with the size of the corresponding active region on the Sun’s visible surface. Active regions are areas where the magnetic field is particularly strong and structurally complex, and they are intimately associated with sunspots, the dark, cooler patches that dot the solar surface when magnetic fields suppress convection. Active regions are widely considered the potential starting points for eruptions, and quantifying the relationship between their size and flare energy is a cornerstone of modern flare forecasting.

Of course, as Krivova noted, the researchers knew that no superflares had occurred during the observation period. The power of the approach lies in the statistical relationship they uncovered: the link between released energy and active region size should hold true for more powerful events as well, extrapolating the physics observed in ordinary flares into the extreme regime that has never been witnessed on the Sun directly. This empirical scaling allowed the team to convert a measurement of active region area into an estimate of maximum possible flare energy, effectively turning the solar surface into a historical archive of eruptive potential.

The second step reached deep into the observational past. Sunspots have been systematically and regularly recorded for about 400 years, beginning with the telescopic observations of the early seventeenth century. As Theodosios Chatzistergos, an MPS scientist and co-author of the new study, explained, these records offer another way to look into the history of our star. Because sunspots are the visible manifestation of the magnetic complexity in active regions, the size of a sunspot group can be used to infer the size of the associated active region, and from there the strength of a possible eruption. The researchers combed through four centuries of sunspot records with particular interest in the rare outliers, the exceptionally large spots that stood apart from the ordinary run of solar activity and represented the most extreme magnetic configurations the Sun has displayed in the modern era.

One such outlier towers over the historical record: the giant sunspot of April 1947. This behemoth covered approximately 0.6 percent of the visible solar disk, and its diameter was about forty times that of Earth. It remains one of the largest sunspots the Sun has displayed since the beginning of systematic solar observations. Remarkably, no superflare erupted from this region during its transit across the solar disk. The Sun, in other words, loaded the barrel but never fired. Yet the new study demonstrates that a sunspot of this size is statistically capable of triggering a superflare in rare cases. The implication is sobering: the machinery for the most extreme bursts of radiation in the stellar repertoire exists on our own star, and it has assembled itself within living memory.

As Krivova put it, our Sun has superflare potential. It can produce massive sunspots that, in principle, can serve as the starting point for the most extreme bursts of radiation. The finding reframes the question from whether the Sun could ever generate a superflare to whether it has done so, and how often. The statistical frequency suggested by Sun-like stars, roughly once per century, means that a superflare could occur within a human lifetime, and that the absence of one during the space age is not evidence of safety but a matter of timing. Whether a superflare has actually erupted on the Sun in the historical period remains one of our star’s open mysteries, but the new work transforms that mystery from speculation into a quantifiable risk that can be studied, modeled, and prepared for.

The practical stakes are considerable. A Carrington-class event alone would stress twenty-first-century technological infrastructure in ways the nineteenth century never experienced, and a superflare, releasing orders of magnitude more energy, would represent a hazard of a different category entirely. Satellites in orbit, astronauts beyond the protection of Earth’s atmosphere, aviation routes over the poles, and continental power distribution networks would all face exposure. By establishing an empirical link between the largest sunspots in the historical record and the energy scales of superflares, the MPS-led team has given space weather researchers a concrete observational benchmark: when the next giant sunspot rounds the eastern limb of the Sun, scientists will be able to assess its eruptive potential with a rigor that was impossible before this study. The Sun’s most violent capabilities, long hidden in the statistics of distant stars and the chemistry of ancient trees, are now written in its own spotted face, waiting to be read.

Subject of Research: Solar superflare potential inferred from historical sunspot records and flare energy statistics

Article Title: Sun: New evidence of superflares

Article References: Sun: New evidence of superflares. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: Sun, superflares, solar flares, sunspots, space weather, Solar Dynamics Observatory, Max Planck Institute for Solar System Research, Carrington Event, active regions, solar activity, stellar flares, Philosophical Transactions of the Royal Society A

The research, published in the journal Space Weather, was co-authored by space weather historian William B. Cade III of Baylor University’s Institute for Aviation Sciences, together with colleagues from Lancaster University in the United Kingdom, the British Geological Survey, Natural Resources Canada, RMIT University in Melbourne, Australia, and RAL Space in the United Kingdom. The team combined scientific observations with railway timetables, archival documents, and nineteenth-century newspaper reports to reconstruct what actually happened on that October night. Their conclusion is elegantly simple: the original account most likely contained a typographical error, with the year 1848 mistakenly printed as 1841. When the correct date is restored, every piece of evidence, from magnetic records to aurora sightings to sunspot observations, falls neatly into place.

The trail begins with an article published by Nature in 1871, which described a very intense magnetic disturbance on October 18, 1841, that interfered with telegraph equipment along the South Devon Railway. In the early days of railway operation, telegraph operators relied on electrical signals to communicate whether sections of track were clear before a train was allowed to proceed. According to the account, the instruments malfunctioned so severely that the superintendent in Exeter initially suspected that someone was playing tricks with the equipment. Unable to determine whether the track near the village of Starcross was safe, railway officials held the train at the station. If the date had been correct, the episode would have stood as the earliest documented case of space weather affecting modern technology, predating even the celebrated Carrington Event of 1859.

Cade, whose research focuses on the history of space weather science, had rediscovered the forgotten Nature article years earlier and brought renewed attention to its possible historical significance. He has spent considerable time examining articles and newspapers from the 1600s to the 1800s to understand how scientific understanding of solar-terrestrial connections progressed, and in 2013 he published a paper citing the Exeter account as the earliest example he could find of space weather impacting technology. The mystery deepened when a research team uncovered a significant discrepancy: the railway line from Exeter through Starcross did not open until 1846, nearly five years after the reported incident. The team also found no evidence of unusual geomagnetic activity over England on October 18, 1841. They invited Cade to join the investigation to help identify possible space weather events that could have inspired the original account and to provide historical context.

The key to solving the puzzle came from an unlikely source: the train’s scheduled departure time. The researchers examined historical railway timetables to determine if and when a 10:05 p.m. train left Exeter for communities along the route. That particular schedule was in place during 1848 and 1849, narrowing the window of possibility considerably. Their attention soon turned to October 18, 1848, the same month and day reported by Nature, but exactly seven years later than the printed date. This time, the evidence lined up with remarkable precision, transforming a frustrating archival contradiction into a satisfying historical detective story.

The corroborating records are striking. Magnetic records from the Greenwich Observatory showed powerful disturbances beginning during the evening of October 18, 1848, exactly the kind of geomagnetic turmoil that would wreak havoc on telegraph circuits. Newspaper reports described brilliant auroras visible across England, while astronomical observations documented a large group of sunspots facing Earth at the time. Together, these independent lines of evidence point to a period of intense solar activity capable of driving electrical currents through the telegraph lines and earth of the era, currents strong enough to render signaling instruments unreliable. The researchers concluded that the original Nature article most likely contained a typographical error, a single mistaken digit that distorted the historical record for generations.

The physics behind the disruption is well understood today. Space weather refers to changing conditions in the near-Earth environment caused by activity on the sun. Solar eruptions can send bursts of charged particles and enhanced magnetic fields toward Earth, and when these structures strike the planet’s magnetosphere, they drive rapidly varying electric currents in the ionosphere. Those currents induce secondary currents in long conductors on the ground, including telegraph wires and, in the modern era, power lines and pipelines. In the 1840s, the electric telegraph was an emerging technology used by railways for communication and signaling, and as the networks expanded, the rise in solar activity exposed a vulnerability that few people knew existed. The Exeter delay captures the precise moment when humanity’s first large-scale electrical infrastructure collided with the sun’s capacity for disruption.

The corrected date also rewrites a small but meaningful chapter of technological history. The Exeter incident was not, in fact, the first recorded technological disruption caused by space weather. That distinction belongs to an event on March 19, 1847, when geomagnetic activity interfered with the Midland Railway’s telegraph system during a vivid auroral display. Still, the Exeter delay remains one of the earliest known examples of space weather affecting infrastructure, occurring more than a decade before the famous Carrington Event of September 1859, when an extreme solar storm caused widespread telegraph disruptions around the world, reportedly shocking operators and allowing messages to be transmitted even after the batteries were disconnected. The 1848 episode now sits in proper chronological context within the early history of solar-terrestrial physics, in the years when scientists were only beginning to suspect that auroras, magnetic compass fluctuations, and sunspots were connected phenomena.

Beyond the correction itself, the study offers a lesson that extends well beyond space science. Historical accounts, even those published in respected scientific journals, can contain errors that persist for generations, and the Exeter story demonstrates how a single typographical slip can reshape the accepted narrative of a field. By comparing magnetic measurements with transportation records, solar observations, and local news reports, the team was able to reconstruct what likely happened on that October night with a confidence that no single source could provide. As Cade observed, the episode is a clear demonstration that as soon as humans developed the first electricity-based technology, it became susceptible to disruption by large space weather events, a vulnerability that has continued and increased to this day with power grids, satellites, communications systems, GPS navigation, and space travel. The result is both a scientific correction and a compelling glimpse into the dawn of our technological dependence on systems that the sun can, and periodically does, disturb.

Subject of Research: Historical correction of the earliest recorded space weather disruption of railway telegraph technology in nineteenth-century England

Article Title: A train, a solar storm and an 185-year-old mystery

Article References: A train, a solar storm and an 185-year-old mystery. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: space weather, geomagnetic storm, telegraph, railway history, solar activity, aurora, sunspots, Carrington Event, Greenwich Observatory, history of science, Baylor University, Space Weather journal

The mystery began with a short report published in Nature describing a very intense magnetic disturbance on 18 October 1841. According to that account, the disturbance interfered with train signals and delayed the 10:05 p.m. departure from Exeter by sixteen minutes. If true, the event would predate the famous Carrington Event of 1859 by nearly two decades and would stand as the first documented case of solar activity disrupting critical infrastructure. Generations of space weather researchers have cited the episode as a historical curiosity, but no one had systematically checked whether the story could actually have happened when the anonymous author claimed it did.

That is precisely what a team led by Lancaster University set out to do, working with scientists from RMIT University, the British Geological Survey, Natural Resources Canada, Baylor University and the United Kingdom’s national space laboratory, RAL Space. Their investigation, published in the American Geophysical Union journal Space Weather, combined an unusually broad set of evidence: railway timetables, historical newspaper reports, records of solar observations, accounts of auroral displays and digitised geomagnetic measurements. The approach treated the question less like a routine literature review and more like a historical detective case, in which every document had to be cross-checked against the physical reality of the railway network in the 1840s.

The critical clue turned out to be startlingly simple. As RMIT University space weather expert Associate Professor Brett Carter explained, the railway line referenced in the Nature account did not even exist at the time of the alleged incident. The Exeter to Starcross line, which the report described, did not open until 1846, almost five years after the supposed 1841 event. In other words, the celebrated first space weather impact on technology rested on what was almost certainly a typographical error in a paper published in 1871. A single wrong digit in a date had propagated through the historical record for more than 150 years.

With the 1841 date debunked, the team turned to the archival record to establish when the Exeter delay actually occurred. By matching the available evidence from timetables, newspapers and geomagnetic data, they concluded that the incident most likely took place on 18 October 1848 rather than 1841. The corrected date changes the historical significance of the event. The Exeter delay remains one of the earliest well-documented examples of space weather disrupting technology, but it can no longer claim to be the first. That distinction currently belongs to an earlier episode: interference with telegraph systems on the Midland Railway in March 1847, which is now the earliest credible report known to researchers.

To understand why the 1840s matter so much, it helps to recall what was happening in the world of technology at the time. The first electric telegraph networks were being constructed during that decade, and telegraph operators quickly began to experience unexplained electrical effects caused by disturbances in the Earth’s magnetic field. Solar activity can induce currents in long conductors on the ground, and the expanding web of telegraph wires criss-crossing Britain and other countries provided exactly the kind of infrastructure that geomagnetic disturbances could disturb. The 1840s, Carter noted, marked a crossing point of no return in the relationship between electronic technology and space weather, a natural phenomenon that has always existed but had never before had human systems to affect. Since that line was crossed, he observed, humans have not looked back.

The most famous early demonstration of that vulnerability came just over a decade later. A massive solar flare and coronal mass ejection in 1859, now known as the Carrington Event, produced aurora borealis as far south as Hawaii and Central America. The displays were so bright that people could read newspapers by their light, and gold miners in the Americas mistook the glow for dawn and began cooking breakfast shortly after midnight. Telegraph systems around the world failed. Sparking lines gave electrical shocks to operators and even caught fire, and some systems continued operating without batteries, driven only by the geomagnetic currents induced in the wires themselves. The Carrington Event remains the benchmark against which extreme space weather is measured, but the newly corrected Exeter story shows that the encounter between solar storms and technology began well before 1859.

Study lead author Professor Jim Wild of Lancaster University said the research challenges the assumption that space weather is a purely modern concern. What the work highlights, he explained, is that space weather is not a new threat but a long-standing natural hazard, and that society has been experiencing its effects on technology for almost as long as electrical technologies have existed. The Exeter train delay, he noted, is fascinating precisely because it sits at the point where emerging technologies first began to encounter the realities of the space environment. By combining historical archives with scientific observations, the team was able to show that the event almost certainly happened in 1848 rather than 1841. Although that means it is not the earliest recorded space weather impact, it remains one of the first clear examples of solar activity disrupting critical infrastructure, and the study demonstrates the value of combining scientific records with contemporary newspaper reports and archival documents when reconstructing historic space weather events.

Dr Mike Hapgood, visiting scientist and space weather expert at RAL Space, described the investigation as feeling like a detective story. He emphasised that the work underscores the importance of preserving older records, which provide the evidence base researchers need to interpret past events and strengthen future predictions. The point is not merely historical. Nearly two centuries after the Exeter delay, railways and other critical infrastructure remain vulnerable to space weather, although through very different technologies, including power systems, signalling equipment, satellite navigation and communications networks. Hapgood cautioned that while today’s space weather capabilities are far more advanced than anything available in the 1800s, the modern technologies society depends on are also much more vulnerable to solar storms, making a deep understanding of past events essential for preparing for and mitigating future impacts, especially as a new solar cycle arrives in the 2030s.

The corrected story of the 10:05 p.m. train from Exeter is a reminder of how easily errors can become embedded in the scientific record, and of how archival work can set that record straight. A typo in an anonymous 1871 Nature report turned a real 1848 incident into a phantom 1841 event, obscuring the true chronology of humanity’s first encounters with space weather for generations. The real history is arguably more compelling than the myth: within a few years of the first telegraph lines being strung across the countryside, the Sun was already reaching out to disrupt them, delaying trains and confusing signals. The study, published in Space Weather under the title asking whether space weather delayed the 10:05 p.m. train departure from Exeter on 18 October 1841, answers its own question with a definitive no, and in doing so gives the technological age a more accurate account of its first stormy meeting with the Sun.

Subject of Research: Historical reconstruction of an 1840s geomagnetic disturbance that disrupted railway telegraph signals in Exeter, England

Article Title: 1840s space weather mystery finally solved

Article References: 1840s space weather mystery finally solved. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: space weather, geomagnetic disturbance, telegraph, railway history, Exeter, Carrington Event, solar storms, Nature 1871, archives, Midland Railway, aurora, Space Weather journal