Unlike the Gregorian calendar that we all know and use, the Druidcraft calendar reconciles the cycles of the moon with the cycles of the sun, based on the 19 year cycle recorded by Meton of ancient Greece. Meton noticed that 19 solar years is the same as 255 synodic months (lunations of the moon).
This means that rather than having months all of different lengths (months of 28/29, 30 and 31 days), the Druidcraft calendar follows the phases of the moon, starting each new month on the new moon and alternating between months of 29 and 30 days. Here we can see the inspiration of the Coligny calendar which also uses alternating months of 29 and 30 days, yet it differs in so much as the Coligny calendar starts the month 8 nights before the new moon. The decision was made with the Druidcraft calendar to start the month on the new moon, as it better fits with the concepts of each month having a light half and dark half. The dark half starting with the new moon, and the light half starting with the full moon. Likewise, the year has a dark half and a light half, with the dark half beginning at the winter solstice. Even the 19 year Metonic cycle has a dark half and a light half. Traditionally, days stated at dusk, and so the first half of the day was the dark half too.
The reason we alternate between 29 and 30 days is because the actual time between one new moon and the next (the lunar synodic month or lunation period – the time it takes the moon to orbit the earth in relation to the sun) is 29.53 days on average. So, by adding a 30th day every other month, our months stay in sync with the lunar cycle.
This results in a lunar year of 12 months totaling 354 days, which is 11 days shorter than the solar year. To reconcile this, a 13th leap month is introduced approximately every two and a half years to bring the months back in line with the solar seasons.
When there are 4 full moons in a season, the 3rd is known as a Blue Moon. When there are 4 new moons in a season, then the third new moon is a leap month. In most years there are 3 new moons in each astronomical season. Leap months are always 30 days long.
Of the 255 months in the 19 year Metonic cycle if half of them are 30 days long, and half are 29 days long, that is 117.5 months each, so we make that 117 short months and 118 long months. Now we apply the rule that the 7 Blue Moons are all 30 days long and it results in a pattern of 110 short months and 125 long months per 19 year period. This keeps the lunar and solar cycles in sync, gaining only one day every 219 years.
In order to follow this pattern use the following rules:
- All Blue Moons are 30 days long
- The month after a Blue Moon should also be 30 days long.
- The first month in the 7th and and 16th year should be 30 days long.
- At all other times months should alternate between 29 and 30 days in length.
The month names that are used on the calendar were originally inspired by the Coligny calendar. But there are many traditions that name each of the moons. For this reason, no particular set of moon names has been selected for the Druidcraft calendar. Instead, all these sources have been used as inspiration and a set of 16 month names have been selected named after the astronomical season in which they occur. Most years are 12 months long, and all the leap moons are skipped. During a leap year, the 13th month can be included in which ever season it happens to fall.
First Winter Moon
Second Winter Moon
-Leap Winter Moon
Last Winter Moon
First Spring Moon
Second Spring Moon
-Leap Spring Moon
Last Spring Moon
First Summer Moon
Second Summer Moon
-Leap Summer Moon
Last Summer Moon
First Autumn Moon
Second Autumn Moon
-Leap Autumn Moon
Last Autumn Moon
Because a lunation cycle can’t be consistently evenly divided to a whole number, Druidcraft Calendar weeks are independent of the cycles of the moon. A quarter of a lunation period is between 7.25 and 7.5 days long. This makes it impossible to have a 7-day week that stays in sync with the moon phases, without including a leap day every two weeks to bring it back in sync, effectively creating alternating 7 and 8 day weeks. This is similar to the system used in the Coligny calendar. Rather than weeks, the Coligny Calendar’s basic unit is the fortnight. It uses a 14-day fortnight followed by either 14 or 15-day fortnight in alternating months. This results in the alternating 29 and 30 day months that track the moon phases. The Druidcraft Calendar already tracks this information with the Lunation ring.
There is another cycle of the moon that is 27.212 days long (lunar nodal period) that has not yet been mentioned, and that is the time it takes for the moon to transition from is most southerly rising and setting point, to its most northerly rising and setting point. The lunar equivalent of the solstices. 27.21 ÷ 4 = 6.8 so this could be measured with a 7-day week (7 x 4 = 28), but it would require a day be skipped every 5 months to stay in sync (the opposite of adding in a leap day).
Alternatively, the week can be divorced from the moon altogether. In order for the sun peg to complete a circuit of 56 holes in 365 days, it must move every 6.5 days, or twice in a 13-day period. The result is 6-day dark week and a 6-day light week, with a 7th extra “transition” day between the end of the second week, and the beginning of the first. Two of the holes are marked by circles that indicate that the sun peg should be moved.
Traditionally since Bayblonian times, the days of the week have been named after the planets. But the druidcraft calendar can’t use that scheme due to the lack of a 7 day cycle. Af first the days of the week on the Druidcraft calendar were named after selected Ogham trees. But there was very little basis for this and so they have been removed. At this point the Druidcraft calendar has no day names. This may change if relevant day names with a good basis are discovered in the future.
Among the pagan community, the exact timing of the new year is disputed. Some say Samhain is the start of the year, others say the winter solstice, others still use December the 24th, January the 2nd or any number of other dates. In the Druidcraft calendar, the winter solstice stands at the beginning of the dark half of the year, and so denotes the start of a new year. However, it could be considered that Samhain is the end of the year, and the period in-between is the time of death and journeying through the underworld.
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