A Mysterious Fog Dims the Sun for a Year

In March 536, residents of Constantinople observed an unusual atmospheric disturbance. The sun began to shed a weak, pale light without radiance, resembling a continuous eclipse. In his history of the emperor Justinian's war against the Vandals, the historian Procopius wrote that the sun gave its light without brightness, like the moon, for the whole year. Farther west in Italy, the Roman statesman Cassiodorus noted that the sun seemed to acquire a bluish tint, mid-day shadows disappeared from the ground, and summer arrived without its usual warmth. The abnormal gloom lingered across Europe and the Mediterranean for well over a year, confusing the natural progression of the seasons and spoiling agricultural harvests.

Similar accounts emerged across the globe in surviving records from East Asia to Ireland. Chinese chronicles described unseasonable cold, frosts and even summer snow that disrupted farming and caused severe famine. A southern Chinese record noted a yellow ash-like substance drifting from the sky that winter, while northern annals linked the sudden drop in temperature to catastrophic food shortages in the Guanzhong region. In Ireland, monastic chronicles recorded an acute failure of bread spanning several years from 536 onward. Even the Mandaean Book of Kings from Mesopotamia noted that modest portions of grain could not be acquired despite offerings of gold.