Japanese scientists have recently discovered an excess of carbon-14 and beryllium-10 in the rings of several trees in a Japanese cedar forest. These are very rare forms of these elements and are usually caused by an explosion in space. The scientists speculate that there may have been an explosion around the years 774-775 A.D. and the remaining particles were trapped in the rings of these trees.
http://news.yahoo.com/space-explosion-blame-tree-ring-mystery-astronomers-205516367.html
