sphaera

Sphaera is the Latin word for sphere and is used in scholarly contexts as a title or designation related to spherical astronomy. The most well-known use is the medieval astronomical treatise commonly referred to as De sphaera, attributed to Johannes de Sacrobosco (John of Sacrobosco).

De sphaera was likely composed in the early 13th century and became a standard introductory text in European universities. It presents a concise overview of the geocentric model of the cosmos and the concept of the celestial sphere, outlining the order of the heavens, the zodiac, and the motions of the Sun and Moon. The work also covers practical topics such as calendar calculations and timekeeping, and it serves as an accessible entry point to the mathematics and observational astronomy of the period.

The text achieved wide circulation through manuscript copies and, later, printed editions beginning in the late 15th century. Its clear structure and emphasis on fundamental concepts helped integrate Aristotelian and Ptolemaic ideas into medieval education and influenced generations of students and scholars before the scientific developments of the Renaissance and the Copernican revolution.

In modern scholarship, Sphaera is used to refer to this influential pedagogical tradition as well as to the broader historical study of medieval spherical astronomy. The term itself continues to appear in discussions of the Latin linguistic heritage in science. See also Sacrobosco and De sphaera.