What happened
A Basel broadsheet by Samuel Coccius, a student of Holy Scripture and the liberal arts, describes several unusual phenomena from the summer of 1566. At the end of July, the sky was said to have turned blood-red at sunrise and sunset, and the sun and moon looked unnatural. The most famous description concerns the morning of August 7: at dawn, a multitude of large black globes appeared in the sky, racing toward the sun at tremendous speed, turning back, and seemingly fighting among themselves. Some of them reportedly turned red and fiery before vanishing. Like the author of the Nuremberg broadsheet, Coccius treated the phenomena as a warning of God’s wrath. The print was illustrated with a woodcut showing black globes above the city’s rooftops.
Witnesses
According to the broadsheet, many residents of Basel; the account was written by Samuel Coccius.
Explanations and hypotheses
Researchers have proposed several explanations: optical phenomena with the sun low in the sky, clouds of smoke or dust, swarms of insects or flocks of birds, and even dark spots in the eyes after looking at the sun. Many historians point out that 16th-century broadsheets were a moralizing genre and described phenomena through the lens of religious signs. For proponents of the UFO hypothesis, it is – alongside Nuremberg – a classic example of a sighting from before the age of aviation.
Disputed A likely explanation exists, but some of the facts are still disputed.
More: Wikipedia (en)