Reversals in Wartime: Alcuin and Charlemagne discuss Retrograde Motion
Mary Garrison|Thomas Charles McLeish
The apparent retrograde motion of the planets was a puzzle for astronomers from ancient world to final establishment heliocentric cosmology in early modern period, but enjoyed an especially rich discussion Carolingian Renaissance. We explore first stirrings eighth-century response this epistemological challenge remarkable series letters between Alcuin York and Charlemagne, sent while latter on campaign against Saxons 798 CE. Their exchange constitutes longest phenomenon Mars' West up that date. Our consideration relevant explores Alcuin's ability marshal diverse complex explanatory narratives observational traditions around problem planet Mars, even as he unable fully reconcile them. Attention his ultimately unsuccessful (and at times contradictory) attempts explanation suggest relied knowledge sources beyond those previously recognized, which we identify. Charlemagne's curiosity about matter can be located much longer context tradition imperial royal concern with heavenly phenomena; same time, heralds ninth-century expansion astronomy away computists' preoccupation solar lunar calendrical data required calculate date Easter towards more wide-ranging observed planetary irrelevant dating computistical calculations. functional, if not geometrical, assumption centrality sun merits further examination general sense lost ideas sustained medieval echoes.
Interfaces: A Journal of Medieval European Literatures|DOAJ (DOAJ: Directory of Open Access Journals)|White Rose Research Online (University of Leeds)