The Celtic Coligny Calendar



The Gaulish 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. The Gaulish Coligny calendar is possibly the oldest Celtic solar/lunar ritual calendar. It was discovered in Coligny, France, and is now on display in the Palais des Arts Gallo-Roman museum, Lyon. It dates from the end of the second century AD, when the Roman Empire imposed the use of the Julian Calendar in Roman Gaul. The Coligny Calendar is an attempt to reconcile the cycles of the moon and sun, as is the modern Gregorian calendar. However, the Coligny calendar considers the phases of the moon to be important, and each month always begins with the same moon phase. The calendar uses a mathematical arrangement to keep a normal 12-month calendar in sync with the moon and keeps the whole system in sync by adding an intercalary month every 21⁄2 years. The Coligny calendar registers a five-year cycle of 62 lunar months, divided into a “bright” and a “dark” fortnight (or half a moon cycle) each. The months were possibly taken to begin on the new moon, and a 13th intercalary month was added every two and a half years to align the lunations with the solar year. 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 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 BC. The Coligny calendar achieves a complex synchronization of the solar and lunar months. Whether it does this for philosophical or practical reasons, it points to considerable degree of sophistication.

To the Celts, time was circular rather than linear. This is reflected in their commencing each day, and each festival, at dusk rather than dawn, a custom comparable with that of the Jewish Sabbath. It is also reflected in their year beginning with the festival of Samhain on 31 October, when nature appears to be dying down. Tellingly, the first month of the Celtic year is Samonios, ‘Seed Fall’: in other words, from death and darkness springs life and light. Another reason for the importance of night in the Celts’ reckoning of time lies in their regard for the moon and the feminine principle which it represents. Certainly, there is some evidence that they observed the solar festivals of solstices and equinoxes, and especially the summer solstice. It is also true that the Druids’ most sacred plant, mistletoe, was associated with the sun. However, the waxing and waning of the moon was of far greater importance.

The Celts showed their respect for the moon by using euphemisms such as gealach—meaning ‘brightness’—, and never referring directly to ‘the moon’. Manx fishermen followed this custom up until the nineteenth century, referring to the moon as ben reine ny hoie (‘queen of the night’). More persuasive, however, is the evidence to be found in the Celtic calendar.

The earliest-known Celtic calendar is the Coligny calendar, now in the Palais des Arts, Lyon. It dates probably from the 1st century BCE, and is made up of bronze fragments, once a single huge plate. It is inscribed with Latin characters, but in Gaulish. It begins each month with the full moon, and covers a 30-year cycle comprising five cycles of 62 lunar months, and one of 61. It divides each month into fortnights rather than weeks, with days designated from observation as MAT (good) or ANM (not good). Each year is divided into thirteen months.

The Coligny calendar achieves a complex synchronization of the solar and lunar months. Whether it does this for philosophical or practical reasons, it points to considerable sophistication.

The lunar months given on the Coligny calendar are as follows:


Celtic names

Modern months







Darkest depths






Stay-home time



Ice time



Windy time






Bright time