The Sun may have unleashed a major radiation blast around 1200 CE, and researchers in Japan say ancient trees kept the score.

The new work ties together two very different archives of the past: carbon-14 locked inside old wood and written accounts of strange red skies. Researchers traced a spike in carbon-14 from buried tree rings and matched it with historical reports that describe vivid red auroras. Together, those clues point to a powerful solar event that struck Earth roughly 800 years ago.

The finding turns buried wood and old sky records into a shared timeline of a forgotten solar outburst.

The study does more than flag one dramatic episode. It also suggests the Sun behaved differently in that era than many scientists assumed. Reports indicate the solar cycles around that time may have run unusually short, a sign of intense and unstable activity. That matters because solar storms do not just paint the sky; they can flood near-Earth space with radiation and reshape the atmospheric record that trees quietly preserve.

Key Facts

  • Researchers linked a carbon-14 spike in ancient tree rings to a solar radiation event around 1200 CE.
  • Centuries-old observations of red auroras helped anchor the timing of the event.
  • The findings suggest the Sun was unusually active, with shorter solar cycles during that period.
  • The research draws on natural records and historical documents to reconstruct space weather from the medieval era.

The discovery adds weight to a growing idea in solar science: Earth’s past holds evidence of extreme space weather that modern records never captured. Tree rings, ice cores, and old chronicles can reveal how often the Sun produces rare but dangerous outbursts. In this case, the match between chemical signals and sky observations gives researchers a sharper picture of a storm that had faded from view.

Next comes the harder question: how often do events like this happen, and what would one mean for a world built on satellites, power grids, and constant connectivity? Researchers will likely test other ancient records for the same fingerprint. If the Sun did swing through bursts of stronger activity than expected, that history could reshape how scientists judge future space-weather risk.