Astronomical Images : Revolution and sphericity of the heavens, and refraction

Johannes Sacrobosco

Astronomical Images

<p style='text-align: justify;'>Very little is known about Johannes Sacrobosco except that he was probably British, taught astronomy at Paris University, and died there in the second quarter of the thirteenth century. <i>Sphaera mundi</i>, his major work, was an extraordinarily popular astronomical textbook for several generations. Manuscripts of it circulated through all the main European centres of learning. It was first published in 1472 in Ferrara, and went through dozens of editions up to the mid-seventeenth century. In this edition of Sacrobosco's <i>Sphere</i>, marginal additions (<i>scholia</i>) were supplied by Francesco Giuntino (1523-90), who was born in Florence, but spent most of his mature life in Lyon. He was a Carmelite friar with a strong interest in astrology. The growth of commentaries on Sacrobosco is effectively emphasised by the fact that his text was accompanied by separate <i>scholia</i> not only by Francesco Giuntino, but also by Elias Vinetus. This group of figures relate to questions of whether the sky is spherical, and why the celestial objects are allegedly enlarged when seen through diaphanous bodies. An analogy is made with coins (<i>moneta nova</i>) seen in water appearing larger from a certain angle.</p>