The Nebra Disc as an Equinoctial Pointer?



The Bronze Age Nebra Disc, discovered in Germany in 1999 and housed at the State Museum of Prehistory in Halle, has an early reported diameter of 31.8cm and thus potentially with a circumference of three Northern Feet (39.6 inches, 1.006m).
 
Nebra Disc Components

Figure 1: The Components of the Nebra Disc
The Nebra Disc

It has been suggested that a circular pattern of stars high and at right of the disc’s vertical diameter may be a stylised form of the Pleiades star cluster in the constellation Taurus.

The thought here is that the disc might identify the star pattern at a specific time of the year, and the position of Pleiades could be significant, as one might then expect neighbouring constellations to be depicted - a hypothesis that no archaeo-astronomer contacted was prepared to discuss.

With the Pleiades in this position, the constellation most clearly identifiable is Orion to its east. Also seen, from east to west, are the constellations Canis Major, Canis Minor, Gemini, Auriga, Perseus, Andromeda, and Aries. Apart from the Pleiades (not particularly easy to spot), twenty or so stars in this view are clearly visible to the naked eye.
 
Depiction of the Autumn Sky

Figure 2: A Depiction of the Autumn Sky: A Nebra Star Plan?
Matching the Star Points to Constellations?

This readily identifiable panorama can be illustrated as in Figure 2, which is a limited representation of the southern night sky with the stars grossly exaggerated, seen in the northern hemisphere late in autumn and into winter (the figure is the view at midnight on November 30th). The panorama can be particularly impressive on clear nights. Note that Orion spans a large portion of the sky and is very easy to identify.

It could be that the stars on the disc were added at different times, yet might it be possible to interpret them to represent this particular sky view? Figure 2 illustrates one interpretation.
A Pointer to the Equinox?

Of course, such an arrangement could be accidental. Nevertheless, one might wonder at what time of the year this view would have been seen in Germany (and elsewhere in Europe) at about 2000 BC. Calculation suggests that this may well have occurred in September, which in view of what the Nebra Disc represents at its sides (the extents of the sun’s annual movement), may be particularly significant.
 
Autumn Sky 2000BC?

Figure 3: The Autumn Sky as it might have been c. 2000BC?
The Sky and Disc in Context?

In this respect, the disc could be a depiction of the night sky at the autumn equinox, perhaps even at midnight. In such case, the puzzling arc or ‘boat’ shape (at the bottom of the disc) may be Corona Borealis, which circles the northern sky (a hint of a megalithic argonautica?) and would probably be seen just above the horizon at this time (as at lower centre in Figure 6.1.4), though it is below the horizon in the present day. An arc of Eridanus, at due south, is probably too faint to depict this crescent or ‘boat’.
 
Nebra Disc Star Map?

Figure 4: A Possible Star Map for the Nebra Disc?
The Nebra Disc, Stars and Constellations?

A possible mapping of the stars to the disc can be seen at Figure 4. The determination of a date for this star mapping would have to be confirmed (hence attempts to interest professional archaeo-astronomers), but astronomy software appears to support the hypothesis. At time of writing, a free software download of Stellarium is available.

Checking the correct timing of the event can be achieved by setting the application date to September 22nd 2000 BC and the latitude and longitude to that of Nebra or its environs (there being no guarantee that the disc originated where found).

As the date may be out of synch, the equinox can be determined by stepping through the days and checking for the number of daylight hours (twelve), the positions of the rising and setting of the sun (at due east and west) and the sun’s local noon altitude (90 - latitude) to be sure of the actual day. Then, move forward or back twelve hours.

The view at south should be much as illustrated above and the view at north should have the Corona Borealis sitting on the horizon like a boat, as at the bottom of Figure 3.
 

Source: Bath G.J. Stone Circle Design and Measurement Vol.2.

© G.J. Bath


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