Illustrations to the Theoricae novae planetarum

Created to accompany Georg von Peuerbach’s Theoricae novae planetarum (1454), this codex attests to the enduring relevance of Ptolemaic astronomy in the early Renaissance. The volvelles (rotating discs) on these pages represent the solid “orbs” associated with the sun; like Ptolemy, Peuerbach believed that celestial bodies orbited within spherical shells. Page 7 shows the deferent orb of the sun (the circle around which its epicycle moves) between the two deferent orbs of the sun’s apogee (the point in its orbit at which it is furthest from the Earth). Page 8 combines the two deferent orbs on the middle disc, showing that they are concentric with the outermost sphere of the world (Primum Mobile). These delicate constructions of paper and thread are rarely as well preserved as in this manuscript.

Peuerbach’s text is essentially an updated version of the anonymous thirteenth-century Theorica planetarum, a popular university text often bound with Sacrobosco’s Tractatus de sphaera (as in MS. Codex 1881). The Theoricae novae planetarum, which incorporates information from the Alfonsine Tables,was first printed in 1472 under the supervision of Peuerbach’s student Regiomontanus; nearly sixty editions followed before the spread of heliocentric astronomy in the seventeenth century. Supplementary volvelle manuscripts such as this one may have been inspired by Peuerbach’s Speculum planetarum, a short text on astronomical volvelles.