The Day the Sun Turned Blue: A Volcanic Eruption in the Early 1460s and Its Possible Climatic Impact—A Natural Disaster Perceived Globally in the Late Middle Ages?

Abstract

Strange atmospheric phenomena visible all over Europe in September 1465 are interpreted as the result of a volcanic dust veil, possibly originating from a re-dated eruption of Kuwae in Vanuatu, in the southwestern Pacific. There is ample evidence (concerning temperature and precipitation) of years without summers from 1465 to 1469 and their subsequent agricultural, economic, and social impact. A second look raises doubts about assigning any clear pattern and reveals a fuzzier picture: an unusually coloured sun was more frequent in the Middle Ages and Early Modern time than originally thought. It is only non-European evidence that proves the events of 1464–1465 were truly global and most likely the result of a tropical volcanic eruption, though its consequences seem to be less cataclysmic than we would normally expect of a Tambora-like event.