On the dusty planes of Nabta in southern Egypt, ancient nomads stopped for a short time to bask in the Nile’s intense summer sunshine. Beneath the Tropic of Cancer, they erected stones that cast no shadows, aligned with the rising and setting of the sun.
The site, known as Nabta, is between 6,000 and 6,500 years old, or about 1,000 years older than Stonehenge. The Nabta site was discovered several years ago by a team led by Southern Methodist University anthropology Professor Fred Wendorf. It appears to have been constructed by nomadic cattle-herders living in southern Egypt. The complex isn’t circular like Stonehenge. It is .8 miles wide and 1.8 miles long. It includes 10 slabs some 9 feet high, 30 rock-lined ovals, nine burial sites for cows, each under a pile of 40 to 50 rocks weighing up to 200 or 300 pounds apiece, and a “calendar circle” of stones. Many of these features line up in five radiating lines, one of them running east-west. The calendar circle is a 12-foot-wide arrangement of slabs about 18 inches long, most of them lying down.
Because Nabta lies near the Tropic of Cancer, the noon sun is at its zenith about three weeks before and three weeks after the summer solstice, preventing upright objects from casting shadows. “These vertical sighting stones in the circle correspond to the zenith sun during the summer solstice,” said Malville, an archeoastronomer at the University of Colorado. “For many cultures in the tropics, the zenith sun has been a major event for millennia.” Two pairs of upright stones stand directly across the circle from each other, defining a view that would have displayed sunrise at the summer solstice. The circle also contains two other pairs of standing stones that defined a north-south view.
via nasa via dailygalaxy