English summary: How Accurate was Star Oddi?

Among items of continental knowledge reported in medieval Icelandic manuscripts we find text inserts from the 12th century onwards describing independent observations of the annual motion of the sun. This choice of field of interest may not be accidental, the observer being located near the Polar Circle where the solar motion is both particularly conspicuous and important. The most important text insert is the so called Oddi's tale, a couple of pages in three sections, attributed to the farm labourer Star-Oddi living in the 12th century. The text clearly claims to be of Icelandic origin and there are no known foreign parallels.

The first section gives the time of summer and winter solstices through a leap year cycle with an accuracy of 3 hours. Its dating of the solstices is independent of the ecclesiastical calendar of its time, indicating own observations. However, the timing of the solstices within the day must be seen as an exercise in the Julian calendar which was being introduced in Iceland at the time. The second section describes how the solar motion increases in sight from winter solstice to summer solstice and then decreases to the next winter solstice. It involves an interesting mathematical method probably taken over from Europe, maybe only through oral channels. The numbers given are also of interest, indicating a mixture of independent observation and a predilection for symmetry and simplicity. The precision of the description is discussed in the paper in close relation to the symmetry. The third section tells us the direction of dawn and nightfall through the year. Its data depend on the latitude of the observer so that it is practically inconceivable that they should have been borrowed from lower latitudes. Whereas the first section of Oddi's tale would primarily have been useful as an exercise in Julian time reckoning, the latter two are probably related to navigational needs.

If the tentative analysis presented is right we have here an example of how the environment governs the knowledge gained by people. However, the initial seeds of an independent astronomy of the North were quenched by European knowledge imported in the 12th and 13th century. Thus we missed the opportunity to see what a full-blown astronomy of the North would have looked like.

Aðalsíða NorrŠn vÝsindi ß mi­÷ldum Ritsmíðar