The source used for finding important dates in the Old Norse calendar is Andreas Nordberg’s book “Jul, Disting and Förkyrklig Tideräkning” (Christmas, Disting and Pre-Christian Chronology), 2006. This is, in my opinion, the most detailed, as well as the best, analyses of the Old Norse calendar. The eBook is available via the link (abstract in English) Jul, disting och förkyrklig tideräkning.
The basis of the Old Norse calendar is formed by the timing of the winter and summer solstices together with the autumn and spring equinoxes. It is the time at which the sun is at its most extreme positions, in summer and winter that decides the date of the winter and summer solstices. The equinoxes fall on the dates when the night and day are of equal length.
In each season of the year in Scandinavia sacrificial ceremonies, also known as blot, are performed. Some examples of blot are the Midwinter Blot and the Disablot, both of which take place in winter, and the Victory Blot during the spring. There probably many names for different blot, and the traditions around them almost certainly vary from region to region. It is likely that the blot fell on either the first full moon or new moon after the winter and summer solstices and after the autumn and spring equinoxes.
A third group of important dates are the new quarters. These probably date from the Roman Iron Age (0-400 AD), arriving at the same time as the days of the week were adopted in Scandinavia.
For the purpose of investigating whether standing stones have been used to mark important calendar days at the burial site, it has been necessary to make a number of assumptions based on Andreas Nordberg’s book.
- In contrast to today, each new day begins at sunset.
- The Blot took place either on the full moon, new moon when there was no visible moon or alternatively the first night of a visible crescent, at the earliest a half moon cycle and not later than one and a half moon cycles after the winter and summer solstices and the spring and autumn equinoxes. The four seasonal blot that I will be mentioning are the autumn blot, the winter blot, the vernal blot and the summer blot.
- The new quarter begins 28 days after the winter and summer solstices and the autumn and spring equinoxes.
How the winter and summer solstices and the vernal and spring autumnal were pinpointed during the Iron Age we have no idea. For the winter and summer solstices I shall use the current definitions. As for the autumn and spring equinoxes there are two possible alternatives to consider.
- The vernal and autumnal equinoxes fall when the suns height is exactly midway between its height at summer and winter solstices. This was the definition used in the Mediterranean lands in Antiquity and gives the same result as that used today. Known in these presentations as the “Height Model Equinox”.
- The vernal and autumnal equinoxes fall when day and night are of equal length. This falls on the day before in spring and the day after in the autumn as compared to the sun-height model above. It is the refraction of light in the atmosphere that causes the discrepancy of one day. Known in these presentations as the “Refraction Equinox”.
According to Andreas Nordberg’s analyses of Middle Age calendar staves, the spring quarter begins 30 days after the spring equinox. It is suggested that this may be a result of difficulties in determining the exact date of the equinox, causing it to be around two days late.
Examples from the oldest sources
We can be certain when the winter and summer solstices and the autumn and spring equinoxes will take place. Using Andreas Nordberg’s analyses we can also be fairly certain regarding the beginning of each new quarter. When it comes to blot days we cannot know if they occurred on the full moon, new moon or the first crescent. On the new moon the moon is not visible and it takes around two days before the first crescent moon can be seen.
Nordberg mentions that Egil’s saga, written at the beginning of the 13th century, “tells of a Norse disablot that took place in autumn when it was hereinafter darkness” He goes on to reference Tacitus, who in his Annuals I recounts “of a Germanic tribe who celebrated a great religious festival under a night illuminated by stars”. Both these examples indicate that it was on the night of the new moon, when the moon is invisible, that these festivals were held and not at the first sight of the crescent. I have not come across any case of the crescent moon being given as the time of the blot. That said, I have not made any thorough studies so there is a risk that my conclusions may be somewhat hasty.
Here I would also like to quote another example from the writings of Tacitus, regarding the Germanic peoples and their gatherings, again taken from Andreas Nordberg’s book:
Tacitus Germania, chapter 11 (circa 100 AD): On matters of less importance the chieftains are consulted, on important matters all of the people, although with the proviso that those matters to be decided by the people will be examined and discussed by the chieftains. As long as no unforeseen circumstances prevent it, assemblies take place on designated days, at the new moon or the full moon as these times are seen as the most favourable on which to begin their ventures. They do not, unlike us, measure time in days but in nights. It is in this way that they hold their councils and reach agreements; in their eyes it is the night that leads the day.