Ancient Japanese writings are guiding using fashionable cutting-edge expertise, as researchers examine medieval solar storms for essential clues to the security of house flight at the moment.
While risky photo voltaic exercise could produce lovely auroras, solar flares, and coronal mass ejections also can create space weather circumstances which are harmful to our near-earth and even ground-based infrastructure.
As the industrial house financial system grows, protecting that infrastructure and human astronauts protected from solar storms turns into an more and more urgent concern. Now, a new examine printed within the Proceedings of the Japan Academy, Series B, goals to assist by offering a long-term understanding of the phenomenon.
Tracking Solar Storm Dangers
Solar storms have come near coinciding with crewed NASA missions prior to now. Between the Apollo 16 and 17 moon missions, the Sun produced main photo voltaic proton occasions (SPE), blasting lethal radiation within the type of high-energy particles at charges approaching the pace of sunshine. Such an occasion would have been catastrophic to the crew aboard these missions, and would nonetheless be at the moment.
In gentle of this, Okinawa Institute of Science and Technology (OIST) researchers have developed a new technique to trace historic photo voltaic climate occasions again to the medieval interval, offering a broader timescale dataset on these essential cosmic occasions. With their new method, the OIST researchers have already conclusively recognized an SPE occasion someday between the winter of 1200 CE and the spring of 1201, as revealed within the new examine.
“Previous studies on historical SPEs have focused on rare, extremely powerful events. Our paper provides a basis for detecting sub-extreme SPEs — events that occur more frequently and are around 10-30% of the size of the most extreme cases, but still hazardous,” mentioned Professor Hiroko Miyahara from the OIST Solar-Terrestrial Environment and Climate Unit.
“Sub-extreme SPEs are more challenging to detect, but our method now allows us to efficiently identify them and better understand the conditions under which they are more likely to occur,” he added.
A New Method to Identify Ancient Solar Storms
The group’s new technique begins by looking historical texts for descriptions of occasions resembling SPEs, then by looking for proof by way of carbon-14 measurements of buried asurano bushes. Notably, carbon-14 compounds type when the handful of SPEs that handle to pierce the Earth’s magnetic area encounter atmospheric gases. Measuring the quantity of those compounds in preserved natural materials offers knowledge on the final 10,000 years of photo voltaic exercise.
Previous strategies for learning these historical occasions captured solely essentially the most excessive carbon-14 spikes, missing the granularity to offer a full image of photo voltaic turbulence over time.
It took the group greater than a decade, however they developed an ultra-precise measurement method able to registering a lot smaller fluctuations than beforehand attainable. These readings permit scientists to establish, for the primary time, sub-extreme historical SPE occasions.
“The high-precision data not only allowed us to accurately date sub-extreme solar proton events, but it also lets us clearly reconstruct the solar cycles of the period,” provides Miyahara. “Today, the Sun’s activity fluctuates over eleven-year-long cycles, but we’ve found that the cycle was just seven to eight years long back then, indicating a very active Sun.”
“The SPE we have dated occurred at the peak of one of these cycles,” he provides.
Solar Storms in Ancient Writing
Where the traditional writing is available in is that the brand new technique is extraordinarily time-intensive, so the group must zero in on possible locations to look relatively than casting a broad web.
Fujiwara no Teika, who lived from 1162 to 1241, was an essential courtier and poet whose writing nonetheless survives. In considered one of his journals, the group famous the February 1204 CE description of “red lights in the northern sky over Kyoto.”
As the photo voltaic floor grows extra turbulent, a number of risky occasions are more likely to co-occur. SPEs could not produce aurora because the diary seems to explain, but they’re more likely to seem similtaneously the photo voltaic flares and coronal mass ejections that produce the colourful occasions.
As the researchers suspected, a pattern of asunaro wooden from Aomori Prefecture, when analyzed with the brand new measurement method, displayed a minor carbon-14 spike, suggesting a sub-extratreme SPE. Comparing tree-ring knowledge from the area allowed the group to slender the occasion’s time interval to between late 1200 CE and early 1201 CE.
“Historical literature provides a candidate time window, and dendroclimatology enables direct intercomparison between detected SPE and reports of sunspots and auroras recorded in literature. Integrated approaches like these are necessary to accurately reconstruct past solar activity, helping us better understand the characteristics of extreme space weather,” concluded lead author Professor Hiroko Miyahara.
“For example, while the SPE we found occurred near the peak of the solar cycle, some of the prolonged low-latitude aurora recorded in the literature seems to fall near the minimum of our reconstructed solar cycle,” he added.
“This is unexpected,” Miyahara concludes, “and we’re excited to look further into what solar conditions could cause this.”
The paper, “Extremely Active Sun from 1190 to 1220 in the Medieval Period: Intercomparison of Historical Records and Tree-ring Carbon-14,” appeared in Proceedings of the Japan Academy, Series B on April 10, 2026.
Ryan Whalen covers science and expertise for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificates in Data Science. He may be contacted at [email protected], and observe him on Twitter @mdntwvlf.