Several prehistoric monuments are known from abroad with levels pointing in significant astronomical directions, in particular from the Middle East. However, these cultures had a written language which can tell us - in present day - about their science. No written language existed in Northern Europe, and we have to base our knowledge of the past on archaeological evidence as well as on the few existing accounts of journeys written by literary people.
Danish historians do not yet accept astronomical explanations to prehistoric findings; instead, they prefer other interpretations. In other countries the subject is more accepted . In England the subject was taken seriously after the interpretation of Stonehenge as a Sun-Moon observatory (Hawkins, 1963). Since then, several stone-monuments have been explained in a similar way. In Germany, the subject has been taken seriously for many years, and a few years ago many Swedish stone-monuments got an astronomical interpretation. The big difference in the significance of the subject can be seen in a comparison of "The Big Danish Encyklopaedia" with the Swedish "Nationalencyklopaedin"; in the Swedish encyclopaedia, 15 times as much is written about the subject as in the Danish encyclopaedia.
From Adam of Bremen (dead 1076) we know that the Swedes in Uppsala had big celebrations every 9th year. Thietmar of Merseburg (dead 1018) mentions corresponding celebrations in Lejre. Nine years is the period of time from which the Moon has its largest difference in rising azimuth to the least difference (½ a Saros period).
It should not come as a surprise that the Sun and the Moon were observed in prehistoric times, because it was the only way to regulate the calendar and the religious feasts.
We know that the horizon around year 1000 in Iceland was divided in eighths, ættir, and the time from the Sun was over one mark to the next was called an eykt; they also used a division in sixteenths, a division we today find in the compass. This method to divide the day must have its roots back in the Nordic history. We find this division of the day on several medieval Sun-dials from Denmark and England.
quite a few stonecarvings. Here is the Sun and
the sixteen divisions at Madsebakke.
with levels pointing in suspicious astronomical directions.
Klosterbakken, Little Hareforrest. In the forest there are many stone-constructions, normally with a big groove-stone in the middle; around the constructions are a number of black squares which show traces of burned bones. The following lines of sight have been found: Sunrise at the equinoxes and the solstices and the rising azimuth of Sirius. In Great Hareforrest a construction with sights to the azimuth of the Moonrise at its extremes has been found.
The Landscape Calendar with its center at Ole Rømer's Hill (the name derives from the belief that Rømer had his countryside observatory at the top; the original name of the hill was the Kings Hill). The hill is a special constructed type, formed as a pyramid, flat at the top, no borderstones and no graves inside. From the hill, you see the sunrise in the direction of Risby Thinghill at summer solstice; in direction of a small hill in Herstedøster at the equinoxes; Sunset in the direction of Beaconhill at the equinoxes; rise of Sirius in the direction of Polehill and the Sunrise in the direction of Ole Rømer's Road (a road, which dates back many years). All the hills are of the above mentioned type.
Sources of information:
Hugh Thurston, Early Astronomy, Springer Verlag New York 1994.
Astronomisk tidsskrift nr. 4/1986, 2/1987 og 2/1994.
Jens Vellev, Danske solure fra middelalderen, Hikuin, 6/1980.
Eden and Lloyd, The book of Sun-dials, Bell & sons, 1900.
E. Laumann Jørgensen, Stjerner, Sten og Stænger, Arkæo-Astronomi i Danmark, Hernov 1994.