When it comes to the Great Pyramid of Giza, our first thoughts tend to relate to the sheer size of this massive structure. However, beyond the size factor, the monument does flaunt its astounding accuracy when it comes to the alignment factor. To that end, the structure, rising to a height of 455 ft and boasting over a base area of around 570,000 sq ft (the equivalent of ten American football fields), is almost immaculately oriented with the four cardinal directions of North, South, East, and West. Simply put, the North-side alignment misses the magnitude of exact preciseness by just a tiny fraction of a degree (which equates to 3/60th of a degree of error).
Now in spite of this incredible feat of civil engineering, Egyptologists and other scholars in the field are still not sure how the ambit of preciseness was achieved by the ancient Egyptians. But an archaeologist might just have solved the 4500-year old puzzle – Glen Dash, who is also an engineer, has reckoned that the ancient architects used the fall (or autumnal) equinox for not only the Great Pyramid but all the major pyramids of Giza and the one at Dashur. He said –
The builders of the Great Pyramid of Khufu aligned the great monument to the cardinal points with an accuracy of better than four minutes of arc, or one-fifteenth of one degree. All three pyramids exhibit the same manner of error; they are rotated slightly counterclockwise from the cardinal points.
It should be noted that there are numerous hypotheses put forth by scholars and researchers when it comes to the alignment factor of these pyramids, with some of the conjectures based on the pole stars and others based on the sun path and shadow. Even equinox measurements were also considered by a few experts, though their assessments were relegated due to the presumed inaccuracy of the conditions. However, Dash has proven that autumnal equinox could have indeed played a crucial role in determining the alignment of the pyramids.
To that end, his experiment utilized a rod known as a gnomon that was placed on a wooden platform on September 22, 2016, thus coinciding with the day of the autumnal equinox (on this day the plane of Earth’s equator passes through the center of the Sun’s disc, and the length of day and night tend to be equal). The positional change of the rod’s shadow was then tracked throughout the day, and it was found to move along a smooth curve trajectory. A straight line between two points on this curve nearly presented the east-west alignment, in a method known as the Indian circle (as pictured above). Quite intriguingly, there is a degree of error in the counter-clockwise direction in this procedure, and the similar degree of error is also found in the alignment of the aforementioned pyramids.
On the literally brighter side, according to Dash (as told to Live Science), the technique would obviously require a more-or-less sunny day, a conducive weather pattern that is usually found at the Giza site. The ancient Egyptians were also aware of the annual date of the autumnal equinox by counting forward 91 days after the summer solstice. And moreover, this method seems to be relatively straightforward and uncomplicated, which would have made it ideal for massive construction projects. But unfortunately, while the hypothesis is sound, archaeologists still don’t possess any actual physical evidence of the alignment method used by the ancient Egyptians. As Dash made it clear –
The Egyptians, unfortunately, left us few clues. No engineering documents or architectural plans have been found that give technical explanations demonstrating how the ancient Egyptians aligned any of their temples or pyramids.
The original study was published in the Journal of Ancient Egyptian Architecture.
Featured Image Courtesy of Ricardo Liberato / All Gizah Pyramids