Circular chromlech at Nabta
Other subterranean complexes
are also found in Nabta Playa,
one of which included evidence
of perhaps an early Egyptian
attempt at sculpture.
One of the world's earliest known examples of archeoastronomy
By the 5th millennium BC these peoples had fashioned one of the world's earliest known archeoastronomical devices (roughly contemporary to the Goseck circle in Germany and the Mnajdra megalithic temple complex in Malta), about 1000 years older than but comparable to Stonehenge (see sketch above). Research suggests that it may have been a prehistoric calendar which accurately marks the summer solstice.
The research done by the astrophysicist Thomas G. Brophy suggests that these monoliths might tell much more. The calendar circle itself is made up of one doorway that runs north-south, a second that runs northeast-southwest marking the summer solstice, and six center stones (see sketch above).
Brophy's hypothesis proposes first that the southerly line of three stones inside the calendar circle represented the three stars of Orion’s Belt and the other three stones inside the calendar circle represented the shoulders and head stars of Orion as they appeared in the sky. These correspondences were for two dates -- circa 4,800 BC and at precessional opposition -- representing how the sky "moves" long term. Brophy proposes that the circle was constructed and used circa the later date, and the dual date representation was a conceptual representation of the motion of the sky over a precession cycle.
Near by the calendar circle, which is made of smaller stones, there are alignments of large megalithic stones. The southerly lines of these megaliths, Brophy shows, aligned to the same stars as represented in the calendar circle, all at the same epoch, circa 6270 BC. The calendar circle correlation with Orion's belt occurred between 6400 BC and 4900 BC, matching the radio-carbon dating of campfires around the circle.
Brophy found that the lines made to these megaliths match the spots in the sky where the various stars rose in vernal equinox heliacal rising. In analyzing the varying distances, mulling through assumptions such as that they represented the brightness of the stars, he inadvertently found that they matched the distance of the stars from Earth on a scale of roughly 1 meter = .8 light years within the margin of error for astronomical distances calculated today.