NASA, ESA, J. Hester, A. Loll (ASU) ===================================================================== Supernovas may have affected the Earth’s climate in the last 40,000 years. Tree-ring data suggests supernovas caused spikes in radiocarbon. Could the next nearby supernova cause a collapse of civilization? ====================================================================== Dendrochronology is a fancy word for tree-ring dating, where the age of a tree can be determined by the number of growth rings across its trunk. But there’s a lot more to learn from looking at a tree’s rings than simply its age. Like fingerprints, tree rings give scientists clues to what the world was like when a tree was alive....