Our recent lunar eclipse was nothing that the Franks hadn’t seen before. The learned and literate believed in the Aristotelian egocentric “concentric spheres” model of the cosmos, which held sway until the 16th century. While we chuckle at the spheres, the model does put the moon in orbit around the earth, and thus does explain that eclipses are caused by the intersection of the earth, moon, and sun.
The understanding of a lunar eclipse by the common people was far more lively.
The common folk believed that the moon was under attack by some malevolent spirit or demon. Before you chuckle at that, consider the evidence: the moon, on the night it is full, so powerfully bright and white, is suddenly and unexpectedly turning an ominous red. This mystifying transition happens slowly, yet inexorably, turning the moon, normally a festive friend, the only real light after sundown, into a shadow of its former self.