Sister Moon and the Stars

Astronomy

Since man has been on earth, he has not been able to help but look up at the sky to admire its beauty. From the position of the stars and the movements of celestial bodies, he then intuited how to measure time and orient himself on land and sea.

The Church has always been interested in studying celestial motions both for its practical relevance – for example, for calculating Easter – and for its significant speculative and theological implications.

Astronomy from Antiquity to the Middle Ages

But what did the sons of Francis study to grasp the secrets of the sky? A significant example is a manuscript containing various mathematical-astronomical treatises, probably a manual for friar students. The codex includes a notable work, the Tractatus de Sphaera, attributed to the famous English Franciscan philosopher and theologian John Peckham, who masterfully combined Greek, Arab, and Latin astronomy and cosmology theories.

Among the “classics” of the discipline stands out the Almagest of the famous Greek astronomer and mathematician Ptolemy, a geometric-astronomical treatise of the highest technical content. Less complex is the Treatise on the Sphere by John of Sacrobosco (John Holywood), which in four chapters provides a brief description of the different parts of the spherical and finite universe.

The Modern Age

A mandatory reference for this period is Galileo Galilei, one of the fathers of the “new” science: on display are his Works printed in 1744 by Giuseppe Toaldo. After Galileo, many other scientists produced works of great scientific importance, among them the Neapolitan Francesco Fontana with his Novae coelestium, terrestriumque rerum observationes, a volume enriched with an intriguing set of images, describing the “curious” celestial novelties he observed. Of a completely different scope is the Astronomia Reformata by the Jesuit Giovanni Battista Riccioli, an eminent scientist of 17th-century Italy, who sought to answer the complex problems that engaged most astronomers of the time. The Franciscan astronomer Ilario Altobelli was the author of the curious Tabulae regiae. A friend and correspondent of many great scientists of his time – Galileo Galilei, Antonio Magini, Cristoforo Clavio, and Giovanni Battista Riccioli – he was probably the first in Europe, in 1604, to observe the appearance of a “new star,” a primacy that Kepler himself considered possible.

Astronomy and astrology

A curious aspect well represented in the volumes on display concerns the relationship between astronomy and astrology, which were intimately connected until the Enlightenment. This is evidenced by the Summa astrologiae iudicialis, a comprehensive treatise on “astrological theory” by Johannes Eschuid Ashenden, who drew on a multitude of sources and ventured predictions based on supposed influences of eclipses and planetary conjunctions.

A very interesting case is a manuscript from the early 17th century, probably compiled “for internal use” by some religious of the convent. The first of the treatises it contains is a brief introduction to astronomy, while the second, more extensive and articulated, discusses in detail ordinary “astrological questions.” The codex is rich in diagrams, calculations, astrological tables, and suggestive images that would raise more than a few doubts in the modern scientific eye.