Main Page


The New Celtic Calendar


Today's date in the New Celtic Calendar is: 5 Samhain, 3045 N.C.E.

Samhain 3045
Lu Ma Ci Ar Ao Sa Do
    
1
9/11
2
10/11
3
11/11
4
12/11
5
13/11
6
14/11
7
15/11
8
16/11
9
17/11
10
18/11
11
19/11
12
20/11
13
21/11
14
22/11
15
23/11
16
24/11
17
25/11
18
26/11
19
27/11
20
28/11
21
29/11
22
30/11
23
1/12
24
2/12
25
3/12
26
4/12
27
5/12
28
6/12
29
7/12
30
8/12
 

The New Celtic calendar is a notional lunisolar calendar that I have devised for my own interest and enjoyment. It is not meant to represent any real calendar that may or may not have ever existed at any time, it is a combination of various possible lunisolar calendars used by different Celtic civilisations. It is inspired by the Moonwise tree calendar and the Gaulish "Coligny" calendar. The Coligny calendar is named after a bronze tablet that was discovered near Coligny, France in 1897 that details the design of a lunisolar calendar (i.e. a lunar calendar that uses intercalary months to the years synchronised to the tropical solar year). The New Celtic Calendar is my attempt to create a lunisolar calendar that keeps in synchronisation with these cycles as closely as possible using a simple rule-based system.

Mean Months and Years

The system used to achieve this synchronicity is based on the 19-year Metonic cycle, whereby the Moon's phases occur on or around the same dates at 19-year intervals. To follow this cycle exactly, though, would result in the months drifting gradually later in the year over a long period of time (this is actually occurring in the Hebrew calendar, whereby the month of Nisan, which contains Passover, is drifting later such that Passover will eventually occur in the summer if it is not corrected). The aim, therefore, is to achieve a mean lunar month as close to the actual mean synodic month and a mean year as close to the actual mean solar year as possible.

A "standard" lunar year has 12 months with a total of 354 days, i.e. 11 days short of a normal solar year. To keep the year in sycnhronisation with the solar year seven of the years have an extra (intercalary) month of 30 days, so a total of 384 days in each year. Four of the other twelve years have an extra day, i.e. 355 days. S0, a standard 19-year cycle has 235 months totalling 6,940 days, which would give a mean lunar month of 29.53191 days (6,940 divided by 235), which is 0.00132 more than the actual mean synodic month of approximately 29.53059 days. This is reasonably accurate but over thousands of years the drift between the calndar and the lunar cycle would be noticeable. If a cycle only has three abundant years, i.e. a total of 6,939 days, then the average would be 29.52776, which is 0.00293 days too short, producing a larger drift over time. With respect to the solar year, a cycle of 6,940 days over 19 years would give an average year of 365.26316 days, which is 0.02078 days too long, whereas a 6,939-day cycle gives a mean year of 365.21053 days, 0.03185 days too short.

Cycles

To achieve greater accuracy, therefore, it is first necessary to use a "grand cycle" which contains multiple 19-year cycles, and then add 3 or 4 days as necessary in each cycle to obtain mean months and years that more closely match reality. This, however, is difficult to achieve using cycles that are exact multiples of 19 years. The answer is to "truncate" one of the cycles from 19 years to 11 years. If this is done in every 18th cycle we get a mean lunar month of 29.53062 days, which is only 0.00003 days longer than the actual mean lunar month, and a year of 365.24252 days, which is only 0.00014 days longer than the actual mean solar year at the present time. This is pretty accurate for a few thousand years before and after the present day.

Structure of the Calendar

The precise structure of the calendar is as follows:

  1. A "grand cycle" comprises seventeen 19-year cycles and one 11-year cycle, i.e. 18 cycles in all;
  2. If these 18 cycles are sub-divided into groups of three, the first and second cycles of each group of three have 6,940 days;
  3. The third cycle of each group of three has 6.939 days, except for the a8th cycle, which only has 4,016 days;
  4. Each of the 19-year cycles has 12 "regular" years of 354 or 355 days, and 7 "long" years of 384 or 385 days;
  5. Each of the 19-year cycles has four "abundant" years with an extra day, i.e. 355 or 385 days depending on whether it is a regular or a long year;
  6. The 11-year cycle has 7 "regular" years and 4 "long" years, and 2 of these are "abundant"
  7. For long-term adjustment, a day is subtracted in every 216th cycle (12 grand cycles), i.e. roughly once every 4,000 years, so that cycle will have an 11-year cuycle with just one abundant year..

The following table shows how each cycle is structured according to the mumber of days in each year if the cycle. The 1st, 2nd and 3rd cycles of each group of three within each grand cycle follow this pattern. The last column shows the structure of each 18th cycle, so this cycle replaces the 3rd cycle in this instance.

Year
1st cycle
2nd cycle
3rd cycle
18th cycle
1
354
354
354
354
2
385
384
384
384
3
354
354
354
354
4
354
355
354
355
5
384
384
384
384
6
354
354
355
354
7
355
354
354
354
8
384
384
384
384
9
354
355
354
355
10
384
384
384
384
11
354
354
355
354
12
354
354
354
 
13
385
384
384
 
14
354
355
354
 
15
354
354
354
 
16
384
384
385
 
17
354
354
354
 
18
385
384
384
 
19
354
355
354
 

By dropping one of the extra days that would normally be added in every 216th cycle (being a multiple of 18), the mean lunar month becomes 29.5306 days, just 0.00001 days of a difference from reality, and a mean solar year of 365.24229, just 0.00008 of a difference. This produces an extremely accurate calendar with regard to the mean lunar month. However, over time the cycles will still drift slightly earlier, such that by the year 10,000 C.E. they will be occurring approximately two days earlier in the Gregorian calendar than at the beginning of the calendar in the year 1,207 B.C.E., approximately 11,000 years earlier. Another small adjustment will therefore have to made at some point to keep the calendar aligned with the solar year, but as it stands the calendar is good for several millennia without adjustment and will correspond more than adequately to the phases of the moon for quite some time.

Structure of the Months

The months in the calendar are as follows:

#
Moon Pronunciation Meaning Days
1
Samhain Sah-vin (Summer's End/Seed Fall?) 30
2
Dumhainn Doo-vin (World Darkness/Darkening?) 29
3
Riùr Roor (Cold & Ice?) 30
4
Naghaid Nah-id (Staying at Home?) 29
5
Uarain Oo-urr-un (Cold/Cold's End?) 30
6
Cuithe Kwee-huh (Wind) 29 {30}*
7
Geamhain Geh-vin (Winter's End?) 30
8
Siùfainn Shoo-fin (Half-spring/Brightening?) 29
9
Eacha Ech-uh (Horse?) 30
10
Eilmì Ell-mee (Claim?) 29
11
Aodhrain Urr-un (Arbitration?) 30
12
Cadal Cad-ull (Song?) 29
13
{Eadràn} Ed-rahn (Intercalary/Between?) {30}**
* Has 30 days in in "abundant" years.
** Is added in years 2, 5, 8, 10, 13, 16 and 18 of every cycle, apart from every 18th cycle, when a month is added in years 2, 5, 8 and 10.

Translation of the names of the months

There is much debate about the names of the months. In fact it is not known even if the months occurred at the times of the year depicted in this calendar, for example "Samonios' may not be cognate with "Samhain". However, the associations and translations used are those generally accepted as being most likely, but it should be noted that nobody actually knows with certainty when in the year the months occurred nor what the true translations of the names are. For example Cadal in modern Scots Gaelic means "to sleep" or "sleeping", but the name of the 12th month may have come from an older word cognate with the Gaulish Kantlos.

New Moon or Full Moon

Another debate is whether the months would have begun at new moon or full moon. In fact, in relation to the Gaulish calendar Pliny the Elder says in Natural Histories, 16, 249: "the sixth day of the lunar cycle - this is from when these tribes count the first days of the months and the year", so the suggestion here is that each new month began on the sixth day following the new moon. However, most known lunar calendars begin each month at or just after new moon (i.e. lunar-solar conjunction) or at first sighting of the new lunar crescent. I have therefore adopted the practice that each month begins at or near new moon.

Epoch and New Year Dates

The epoch of the calendar is 8th November -1026 Gregorian (i.e. 1,027 B.C.E.). This date was not chosen specifically but was arrived at by working back from the start date of the current cycle, 9th November 1999. The latter date was chosen for personal reasons, and as a result each cycle has been starting on or around the 9th November. The calendar is structured, however, to keep the average start date nearer the 5th-6th November, which is the mid-point between the autumnal equinox and the winter solstice. Within a 19-year cycle, the date of the start of each year thus varies from around 22nd October to 19th November.

The date of each new year, therefore, will usually be the nearest new moon to the halfway point between the autumnal equinox and the winter solstice. Some traditions would place the new year date, i.e. the start of the month of Samhain, earlier than this so that it is the full moon that is closest to the midpoint that Samhain is celebrated. In my version, however, Samhain is celebrated at the nearest new moon, as there is nothing that says that all festivals were held at night or that a full moon was required to do so. True, they did not have electric light, but they had fire, and at Samhain fires are often lit as part of the festivities. It is not without credence, therefore, that they did this to light up the darkness and worship the artificial light that would be needed over the winter period. This ritual may have similar origins to Diwali, the Hindi festival of lights, which coincides with the Celtic new year in most years. The short answer is "nobody knows", but the new moon system is the one that I have chosen to go with.

The following table shows the starting dates of each year in the current trio of lunar cycles.

Year
Cycle 163
Cycle 164
Cycle 165
1
8 Nov, 1980
9 Nov, 1999
9 Nov, 2018
2
28 Oct, 1981
28 Oct, 2000
29 Oct, 2019
3
17 Nov, 1982
16 Nov, 2001
16 Nov, 2020
4
6 Nov, 1983
5 Nov, 2002
5 Nov, 2021
5
25 Oct, 1984
26 Oct, 2003
25 Oct, 2022
6
13 Nov, 1985
13 Nov, 2004
13 Nov, 2023
7
2 Nov, 1986
2 Nov, 2005
2 Nov, 2024
8
23 Oct, 1987
22 Oct, 2006
22 Oct, 2025
9
10 Nov, 1988
10 Nov, 2007
10 Nov, 2026
10
30 Oct, 1989
30 Oct, 2008
30 Oct, 2027
11
18 Nov, 1990
18 Nov, 2009
17 Nov, 2028
12
7 Nov, 1991
7 Nov, 2010
7 Nov, 2029
13
26 Oct, 1992
27 Oct, 2011
27 Oct, 2030
14
15 Nov, 1993
14 Nov, 2012
15 Nov, 2031
15
4 Nov, 1994
4 Nov, 2013
3 Nov, 2032
16
24 Oct, 1995
24 Oct, 2014
23 Oct, 2033
17
11 Nov, 1996
12 Nov, 2015
12 Nov, 2034
18
31 Oct, 1997
31 Oct, 2016
1 Nov, 2035
19
20 Nov, 1998
19 Nov, 2017
19 Nov, 2036

Important Dates

The most important dates in the Celtic year are based on the four cross-quarter days (mid-point between solstices and equinoxes), except that they are movable and based on the lunar calendar. For example, in 2018 these dates were:

  • Là Fhéill Brìde (1 Naghaid): 16th February
  • Bealtainn (1 Geamhain): 16th May
  • Là Lùnast (1 Eilmì): 13th August
  • Féill na Shamhna (1 Samhain): 9th November

Dates and the Day Count

The day count is a series of four numbers, separated by full stops, denoting the cycle, year, month and day. The day count today is 165·1·1·5.

The day count is used purely to work out where the current month is located in years and cycles so that the correct number of days can be applied according to the rules. It is not meant to be used as an alternative date notation, as is the case with the Mayan Count, the normal date notation is day-number month-name year, i.e. 5 Samhain, 3045 N.C.E. (N.C.E. stands for Notional Celtic Epoch).

The date and day count of a particular date in the Gregorian calendar can be calculated using the calculator at the following link: Celtic Calendar Date Calculator.


Main Page