What the Monks Saw: A Medieval Mystery

Just to show that life is full of unexpected turns, on June 18, 1178, a group of medieval English monks threw a fine puzzle in the laps of astronomers that lingers to this day. On that day, shortly after sunset, five monks at the abbey of the Christ Church of Canterbury (on the site of Canterbury Cathedral,) noticed that something very odd was happening in the sky. Gervase, who was Canterbury’s…