The Great Midwinter Sacrifice and the Royal Mounds at Uppsala

     Old Uppsala (Gamla Uppsala), a few kilometres north of the modern city of Uppsala, was the old, Swedish, heathen, cult-centre, famous for its three, large, "royal", burial mounds. In 1986, I noticed that these three mounds had been carefully aligned and had the same orientation as the majority of the Swedish passage graves. It was also possible to relate this orientation to the lunisolar calendar that was used to determine the date of the periodic sacrifice of humans and animals at the midwinter full moon every eight years, according to the lunar, eight-year cycle. Representatives from the whole country had to take part in this sacrifice, in which 8 males - one human and seven animals - were hanged in a holy tree every day for nine days.
     The oldest description of this sacrifice was written by a German missionary, Adam of Bremen, in 1075. According to him, there was a great sacrifice in Uppsala every ninth year, but this interval is probably due to a misunderstanding. In the old Nordic language, the first year was counted from the first day of that year and after eight years the ninth year was reached. Therefore the meaning of the text is that this sacrifice took place every eighth year, as we would say.
     The three mounds are oriented in the direction in which the sun set on 3 November and 8 February. In ancient Sweden, the year started at the first new moon after the 21st of October, according to the modern calendar. This means that the first full moon of the year could earliest appear at the 4th of November, only one day after the sun set in the direction in which the northern sides of the three mounds were oriented. This difference is insignificant because the dates of the full moon were fixed to only 19 of 30 days in a month, computed according to the principles preserved on the runic-calendar sticks (runstavar).
     Three lunar months later, on 8 February, the sun sets again in the same direction. Another three lunar months later, on 29 April, the sun rises in the opposite direction. This is the pagan Walpurgis night which is still an important celebration in Sweden and especially in Uppsala (Valborgsmässoafton). Every 19th year, the moon will be full on all three of these days.
     By comparing historical events with computations of full moons, it has been possible to identify the unique, eight-year cycle for this important midwinter sacrifice (Henriksson 1991, 1992). It took place at the full moon that occurred in our calendar between 28 January and 26 February, the so-called Disa Thing period (Distingsperioden). The first day of the sacrificial period, 28 January, may have been defined by observations of the setting sun at the top of Tunåsen, the highest natural hill in the otherwise flat landscape, from an upright stone on Tingshögen, the fourth large but flat mound.
     The same dates were already important in the Neolithic calendar that was marked by grooves in the bed rock on the island of Gotland in the Baltic and by the orientation of the passage graves in Västergötland. The oldest grooves were made on 27 January 3294 BC and the passage graves can be dated to 3300 BC (Henriksson 1983, 1985, 1989, 1992, 1994).
     On the last day, 26 February, the sun set on top of the originally smaller, Middle Mound, the oldest of the three "royal" mounds. This mound has been dated by Sune Lindqvist to AD 450-500 and may be the tomb of the semi-legendary King Aun or Ane the Old, who is believed to have reigned sometime in this period, (Lindqvist 1955). There was a 304-year period, called Aun's period after this king, at the beginning of which the full moon would occur one day earlier in the Julian calendar, (Rudbeck 1689). Such an event took place in the year 1692. Counting backwards in 304-year intervals, we arrive at the year 476 as a likely starting-point for the cycle, if it is to be connected with King Aun. This would mean that the Julian calendar must have been introduced into Sweden no later than this year (Henriksson 1992).

Summary from 'Riksbloten och Uppsala högar', Tor 27, 1995, by Göran Henriksson.