This stunning set of images come from a 16th-century treatise on comets, created anonymously in Flanders (now northern France) and now held at the Universitätsbibliothek Kassel. Commonly known as The Comet Book (or Kometenbuch in German), its full title translates as “Comets and their General and Particular Meanings, According to Ptolomeé, Albumasar, Haly, Aliquind and other Astrologers”. As the title (and indeed medieval origins of the book) suggests the focus is on the meaning of comets, the associated folklore and superstitions as played out on Earth, as opposed to an exploration from a scientific standpoint (the telescope would not be invented until the following century). Comets then are seen in terms of their mysterious terrestrial effects, which as a rule firmly occupy the disastrous category ("disaster" being Latin for "bad star") — devastating fires, wrecking winds, bloodshed, pestilence, famines, and a fair few celebrity deaths. As any dinosaur would tell you, the association of comets and meteors with calamitous events are not entirely unfounded — one comet, named here “Veru” (depicted as a fiery lance) and now known as Swift-Tuttle, has been described as "the single most dangerous object known to humanity" (though the chances of it hitting Earth are still extremely small).
According to a 1977 article by Jean-Michel Massing, most of The Comet Book's chapters have their origins in an anonymously authored treatise Liber de significatione cometarum [A book on the meaning of comets] made in Spain around 1238. In the fifteenth century this was translated into French, a translation which itself spawned various illustrated abridged versions that same century. It is one of these abridged versions which, a century on, would have provided the basis for The Comet Book, not just for the text but also imagery. The latter however have been spectacularly upgraded. While, according to Massing, the formal depiction of the comets themselves don't change so much, in this 16th-century version they have been pulled from their positions inline with the text and flung into the skies of a series of stunningly coloured full-page landscapes.
The stylised depictions of the comets echo the fantastical bent of the text — "Veru" as a lance, "Domina capillorum" as burning wheel, "Rosa" with beaming face, and "Scutella" as some kind of heavenly Asclepius’s staff. In the landscapes below which the comet's stream we see some evidence also of their perceived effects — for example, in the print for "Aurora", which was thought to be an omen of impending conflagrations, a city rages with fire. As the keen observer will note, fiery emissions are not limited only to the skies or burning cities. In the image for "Miles" — whose effects include an upset of social norms — a Bruegel-esque character can be spied defecating in the bottom right corner.
This Comet Book is in fact one of two near identical treatises. The second version (now in the Warburg Library in London) is very likely the work of the same scribe and artist, the main difference being that the Warburg copy sports an additional chapter and a slightly different running order for the comets (the result of a mistake when the Kassel copy was bound in 1969).
Lastly, for a book about fiery apparitions, it is perhaps not entirely inappropriate to learn that this Kassel copy comes to us today with some heat damage — not from comets but bombs. In September 1941, a hundred allied planes flattened Kassel in a raid in which 350,000 or so (almost 90%) of the State Library’s books and printed materials were destroyed. Thankfully the glorious Comet Book survived.