From ancient Greece to medieval Europe
There are numerous surviving scientific discussions of eclipses written by Christians from across the medieval period.
In the 7th century, St Isidore of Seville explained in his encyclopedic Etymologies a lunar eclipse occurs when the Moon, not having its own light, moves into the shadow of the Earth. He also knew lunar eclipses could only occur on the 15th lunar day as they happen only when the moon is full.
Isidore drew on classical sources that translated the theories of ancient Greek astronomers into Latin, the language of the medieval Church in western Europe.