Approximately 14,000 years ago, the unprecedented solar event—now judged to be the most powerful known to have occurred—marked Earth’s transition into the Holocene epoch, according to the findings of an international team of scientists. The team traces the event to around 12,350 BC using a new climate-chemistry model specifically designed to reconstruct ancient solar particle activity. This expands the known timeline for ancient solar storms and raises the bar on the upper boundaries of their intensity. Although the event in question was already known from past observations of radiocarbon spikes in ancient wood samples, its scale and magnitude remained unknown....