The Coligny Calendar

 

The earliest-known Celtic calendar, the Gaulish "Coligny calendar" (discovered in Coligny, France), is dated to the 2nd century CE (when the Roman Empire imposed the use of the Julian Calendar in Roman Gaul) and as such firmly within the Gallo-Roman period. The Coligny calendar is possibly the oldest Celtic lunisolar ritual calendar. (The astronomical format of the calendar year that the Coligny calendar represents may well be far older, as calendars are usually even more conservative than rites and cults. The actual date of its inception is unknown, but correspondences of Insular Celtic and Continental Celtic calendars suggest that some early form may date to Proto-Celtic times, roughly 800 BCE.) It is made up of bronze fragments, but was once a single huge plate. The Coligny calendar achieves a complex synchronization of the solar and lunar months. The lunisolar Coligny calendar was used by Celtic countries to define the beginning and length of the day, the week, the month, the seasons, quarter days, and festivals. Some feast days of the medieval Irish calendar have sometimes been speculated to descend from prehistoric festivals, especially by comparison to terms found in the Coligny calendar.