In 775 AD, something happened on the Sun.
There were no satellites to record it, no power grids to collapse, no newspaper headlines.
But a record of what happened was preserved in tree rings — and it took more than twelve centuries to decipher it.
In 2012, researcher Fusa Miyake was analyzing a cross-section of a 1,900-year-old Japanese cedar when she noticed something unusual in one of its rings.
The ring from 774–775 AD contained a 12% increase in carbon-14, an isotope produced in the upper atmosphere when cosmic rays collide with it.
That jump was 20 times larger than the normal year-to-year fluctuations driven by the solar cycle.
Other teams soon confirmed the same anomaly in samples from Europe, North America, and Oceania, establishing that the phenomenon was global.
Here’s how it works: when an extreme solar storm reaches Earth, energetic particles bombard the upper atmosphere, producing carbon-14.
That isotope drifts down over months into the troposphere, where trees absorb it and store it in their wood.
Each ring is, in effect, a yearly snapshot of what happened in the sky above.
What Is a Miyake Event — And How Many Have Been Confirmed?
A Miyake event is an exceptionally powerful coronal mass ejection from the Sun.
These ejections carry charged particles capable of disrupting Earth’s magnetic field.
Since the initial discovery, Miyake and other researchers have confirmed five additional cases: 12,450 BC, 7,176 BC, 5,259 BC, 664–663 BC, and 993 AD.
That brings the total to six verified events over the past 14,500 years.
What worries scientists most is their unpredictability: they follow no discernible pattern, so there’s no way to know when the next one might strike.
The most recently pinpointed event dates to the 7th century BC.
By analyzing tree rings and polar ice cores, a team narrowed the date to 664 or 663 BC — finally fixing the timing of the one Miyake event that had remained uncertain.
The study, funded by NASA and the European Union, was published in Nature Communications Earth & Environment and drew on samples from Siberia.
Ten Times More Powerful Than the Worst Event on Record
The standard benchmark in space weather science is the Carrington Event — the most powerful geomagnetic storm in recorded history, which struck in 1859.
That storm destroyed telegraph systems across Europe and the Americas and produced auroras visible at tropical latitudes.
The 774–775 AD event was at least ten times more powerful.
The Carrington storm produced a carbon-14 increase of less than 1% in tree rings. The 775 AD event generated a spike of 12%.
That’s why researchers believe the Miyake event far exceeded the G5 category — the maximum on the geomagnetic storm scale.
Among the most recently proposed candidates is a possible event from 12,350 BC, identified in tree rings from the French Alps, whose magnitude could be more than double that of any other known Miyake event.
Why Scientists Are Sounding the Alarm
What concerns researchers isn’t just the historical record, but what would happen if one struck today.
A Carrington-scale event would cause worldwide electrical and communications outages lasting weeks. A Miyake-scale event could produce blackouts lasting months, crippling the infrastructure modern life depends on: power grids, satellite navigation, and the internet.
At best, space-weather monitoring would give us anywhere from a few minutes to a few hours of warning.
The blackout that struck the Iberian Peninsula in April 2025 — which cut 15 gigawatts of power in a single second and took up to ten hours to resolve — shows just how fragile our reliance on a constant power supply really is.
That outage was technical, not solar.
What a Miyake event could unleash is on another scale entirely.
Researchers note that tree rings let them measure the strength of these storms — but the data reveals no pattern they could use to predict the next one.
The energy these events release affects not just radiocarbon levels but the atmosphere’s chemistry as a whole — something scientists are still working to fully understand.
