Overview
- An OIST‑led group, publishing Friday in a Japan Academy journal, reports a sharp carbon‑14 jump that dates a major solar proton event to winter 1200 through spring 1201.
- Researchers paired Fujiwara Teika’s Meigetsuki, which notes a low‑latitude red aurora, with high‑precision tests of buried Aomori tree rings to target the right years.
- High‑energy particles from such solar outbursts create carbon‑14 in the atmosphere, which trees lock into annual rings, allowing scientists to time the blast to a single growth season.
- The event’s scale is estimated at more than ten times the largest directly observed modern counterpart from February 1956, pointing to rarer but far more extreme risks.
- The team found no carbon‑14 spike for the diary’s February 1204 aurora and inferred a shorter 7–8 year solar cycle then, underscoring that visible auroras do not always track global particle storms and that better links to forecasting for satellites and astronaut safety are still needed.