An Astronomical Interpretation of the Nebra Sky Disc

Abstract

We agree with the interpretation of W. Schlosser, that the Nebra Sky Disc is a reminder of a method of determining a start date (and possibly also an end date) of the farming year. We extend this interpretation. We think that we found the constellation Taurus on the Disc, which forms by addition of three stars from the constellation Gemini the pattern of a plough of Bronze Age. Moreover we found a line on the disc consisting of the stars epsilon Gem, theta Aur, beta Aur and alpha Aur, which we called the Auriga line. We think that the Nebra people used the Auriga line to determine the day (which we call beta day) on which the Pleiades are vertically below beta Aur at dusk in February. We found a second representation of the Auriga line on the Disc where the distance ratios between the stars are very precisely equal to the distance ratios in the sky, and where the Pleiades are vertically below beta Aur. This proves that the Nebra people must have measured the distances, and that our hypothesis is correct. The beta day could have been used to harmonize a lunisolar calendar with the solar year. However, the most likely possibility seems to us that a good sowing date could be determined by setting the sowing on the second round lunar phase after the beta day. (By round lunar phases we mean the full moon and the new moon.) Such a sowing date makes it possible to start a week count based on the lunar phases with the sowing in order to determine other agricultural dates. The astronomical knowledge for this procedure can be gained by astronomical observations only. No mathematical calculations and import of knowledge from a Mediterranean culture are necessary.