The Anglo-Saxon Lunar Calendar

Like the Anglo-Saxon solar calendar, this is a notional calendar based on the Anglo-Saxon month names which, as far as we know, were used in the solar calendar. However, it is likely that this was preceded by a lunar calendar which was kept in step with the tropical year by using the solar months to name the lunar months. This calendar is my attempt to recreate this.

There are traditional names for the full moons during a year, which are designated according to the month in which they fall, e.g. the September full moon is the Harvest Moon and the October full moon is the Hunter's Moon, etc. On looking at this further, however, it will be seen that the April full moon was the Egg Moon, which has become linked to Easter. It is probable that this full moon was the first one following the northern spring equinox, and was the original date of the Easter (Eostre) festival before it was Christianised and made to fall on a Sunday.

The Before Yule and After Yule full moons would have been the same, i.e. the last full moon before the winter solstice and the first full moon after the winter solstice respectively. So it seems that the names of the full moons could actually be linked to these events of the tropical year, and that the Harvest Moon, for example, was the one following the autumnal equinox, i.e. in the month of Hærfestmonað (Harvestmonth), also known as Halegmonað (Holimonth), which runs from 23rd August to 22nd September. If a full moon occurs twice in any month, then that month is effectively doubled, and is, in effect, an intercalary month.

Based upon this, then, I have devised the following, notional, table of the full moon names along with the times they occur.

The name of the moon is determined by the date and time that opposition occurs, times being UTC. On this basis, I have named the moons for the years 1561-4 A.S.E. (2005-8) as follows, with the date for each full moon. (N.B. These are "nominal" full moons - see below.)

N.B. If there are ever two full moons in Rethemonth, then only the second one becomes the Lenten Moon, as there cannot ever be two Lenten Moons. The first one would thus become a second Snow moon. Likewise, there are never two Egg Moons. In this event, the first one in Eastermonth is the Egg Moon, and the second one becomes the first Milk Moon, with a second Milk Moon later following it. This happens in 2008.

Calculation of Lunar Months

The dates of the new and full moons are established not by observing th real moon, but by using a system of epacts, like the Gregorian lunar calendar that is used to establish the date of Easter. Under this system, each year in a 19-year Metonic cycle is assigned a number called an epact, which is essentially the age of the moon at the beginning of the year. By labelling all of the dates in the year in a certain way, the new moon in each month can be established by the label identified by the epact for that year (see below).

The Epacts

Because the Gregorian calendar (and the Anglo-Saxon solar calendar) do not have a constant frequency of leap years (one is skipped every century year not divisible by 400), the epacts change from time to time. The table below shows the epacts for the current period, i.e. 1900 to 2199. The years for the current 19-year cycle are also shown.

The dates in each month are then labelled with numbers, counting downward from 30, with a day doubled every month to account for 29-days months. The labels are shown in tables at the bottom of this page (for these purposes the year is taken as starting on 21st March):

From the tables above, the date of the new moon in Ostermonth 1564 (2008) can be worked out by taking the new moon epact for that year (14) from the first table, which indicates 17th Ostermonth (6th April) in the second table. In Thrimilch new moon would be on the 15th (5th May) and in Forelithe the 14th (4th June). The full moon epact is calculated by adding 14 to the new moon epact (because the nominal full moon is considered as falling on the 15th of the month). So, the full moons will fall on 2nd Ostermonth (22nd March), 1st Thrimilch (21st April), 30th Thrimilch (20th May) and 29th Forelithe (19th June).

The full set of labels for each date in the year isshown below.