Ancient text may describe cosmic-ray event

Nature : An Anglo-Saxon historical text may shed light on a mysterious radiation spike recorded in Japanese cedar tree rings in AD 774 or 775, writes Richard Lovett for Nature. The connection was made by a biochemistry undergraduate at the University of California, Santa Cruz. After hearing about a team of researchers in Japan who had found the odd spike, Jonathon Allen did “a quick Google search.” In the eighth-century pages of the Anglo-Saxon Chronicle, whose online version is part of Yale University’s Avalon Project , he found a reference to a “red crucifix” that appeared in the sky “after sunset.” In a Nature Correspondence, Allen proposes that the phenomenon could have been a supernova explosion that created a burst of high-energy radiation, which struck Earth’s upper atmosphere and was recorded in the Japanese tree rings.