Ancient Text Gives Clue to Mysterious Radiation Spike

Ancient Text Gives Clue to Mysterious Radiation Spike

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An eerie “red crucifix” seen in Britain’s evening sky in AD 774 may be a previously unrecognized supernova explosion — and could explain a mysterious spike in carbon-14 levels in that year’s growth rings in Japanese cedar trees.

A few weeks ago, Jonathon Allen, a biochemistry major at the University of California, Santa Cruz, was listening to the Nature podcast when he heard about a team of researchers in Japan who had found an odd spike in carbon-14 levels in tree rings. The spike probably came from a burst of high-energy radiation striking the upper atmosphere, increasing the rate at which carbon-14 is formed. But there was a problem: the only known causes of such radiation are supernova explosions or gigantic solar flares, and the researchers knew of no such events in ad 774 or 775, the dates indicated by the tree rings. Allen did a quick Google search and found the eighth-century entries in the Anglo-Saxon Chronicle at the Avalon Project, an online library of historical and legal documents hosted by Yale University. Scrolling down to the year ad 774, Allen found a reference to a “red crucifix” that appeared in the heavens “after sunset”.

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