Egyptians were not alone in their early turning to the sun. Far beyond the great Nile valley and even the Mediterranean, on the distant edge of the Eurasian continent, a little-understood people also figured out a close approximation of the solar year a few centuries after the Egyptians. We know this only because they left behind what appears to be an enormous calendar constructed out of immense slabs of bluestone, standing upright to form megaliths, some of them topped by lintels called henges. Standing on the barren Salisbury plain, this structure, Stonhenge, was used for over two thousand years by ancient Britons, who aligned the stones so that at the precise moment of the summer solstice a ray of sun shines down the main avenue and into its centre. But what was this for? Is Stonhenge truly an enormous calendar? Or is it an observatory, a fortress, a temple, a Bronze Age place of assembly - or all of the above?
No one knows for sure, though the layout leaves no doubt that the people who built it were astronomically sophisticated enough to buiild a device to accurately measure the solar year. Further evidence comes from stones erected in patterns around Stonehenge that align with the sun at both solstices and at the equinoxes, and with the moon as it runs through its orbit around the earth. This giant calendar would have allowed an ancient Briton to anticipate astronomic cycles and events as accurately as the Egyptians watching Sirius - or, for that matter, a modern astronomer using solar and star charts. Some have claimed that Stonehenge can also foretell eclipses of the moon, which occur regularly after those months when the full moon rises precisely down the main avenue.
David Ewing Duncan. The Calendar.