An exceptionally powerful geomagnetic storm generated a massive, brilliant aurora display that was visible across central and southern Europe, turning the night sky a deep crimson over cities like Prague and London. Coming immediately in the wake of escalating religious tensions and the Battle of Lepanto, the blood-red sky was widely interpreted by the public as an explicit supernatural sign of impending apocalyptic warfare, mass slaughters, and divine judgment on human heresy.

The terrifying display spawned a massive wave of illustrated broadsheets and early news poems across Germany and England. It provided late-Renaissance writers with a rich, dramatic vocabulary of celestial blood and fire that heavily influenced the dark, portentous imagery found in Jacobean tragedy and religious verse.