Abstract: Astronomy, Space, and Time in Medieval Churches
It is a commonplace that in the Middle Ages the Christian church – as an institution – was the primary center of education, including education in the sciences. Less well known is the fact that Christian churches – as physical structures – embodied and portrayed elements of astronomical learning in a way that was accessible to, and used by the general populace.
This astronomical learning was practical in focus and concerned areas where astronomy intersected with the ritual and practical concerns of medieval society with the organization of time and space. Medieval people expressed two principal aspects of time in the construction and decoration of their churches: the time of year and the time of day.
Churches provide two different expressions of the time of the year. One, which only becomes apparent from the examination of large groups of churches, is the practice of orienting churches to face sunrise at the time of the vernal equinox, which was traditionally believed to be the time of Creation. More easily seen, but perhaps not so easily recognized by modern observers, are the many depictions of the signs of the zodiac and the corresponding labors of the months, which reflect the influence of the annual apparent motion of the Sun through the signs of the zodiac upon the changes of the seasons.
Since antiquity, the ability to measure the changing time of day by observing the motion of the Sun was seen as separating man from the beasts. Clerics and layfolk needed to know the times to pray, so it is not surprising that a range of sundials of varying degrees of complexity adorn medieval churches. With the development of mechanical timekeepers these also found their place in medieval churches. Some were simple timekeepers, but others went beyond mere timekeeping to provide models of the cosmos, displaying the motions of the Sun, Moon, and planets, the changing time of Easter and even the times of solar and lunar eclipses. As mechanical timekeepers came to display the regular passage of time, a simpler, but more precise, form of astronomical timekeeper emerged to synchronize these manmade timekeepers with the machina mundi, the machine of the universe. These meridian lines marked the passage of the Sun directly to the south to identify the moment of noon.
We are familiar with the notion that the religious imagery that adorned medieval churches served as books in stone and paint and glass and provided a way to teach medieval people religious lessons. The astronomical elements embodied in medieval churches complemented this religious imagery by teaching the basic astronomical relations of space and time.