Tree-ring data from A.D. 774 show a sudden spike in radioactive carbon 14, pointing to a burst of charged particles or high-energy radiation that struck Earth. A relatively nearby gamma-ray burst could be the culprit. John Matson reports
Gamma-Ray Burst Fingered for Carbon 14 Spike in A.D. 774 | 60-Second Space podcast - Listen or read transcript on Metacast
