The first scientific treatise on aurora borealis was published by Marcello Squarcialupi, an Italian medical doctor working in the court of the Hungarian Prince of Transylvania. His book, De coelo ardore, described the aurora of 10 September 1580 in great detail, providing exact data from his personal observations on the time, direction, shape, colour, and variability. He invoked a rational explanation, bringing up only natural causes, and confronted these with the ruling Aristotelian view. The original Latin text describing the aurora is provided, with an English translation. [ABSTRACT FROM AUTHOR]