Location of burial chambers is not the only riddle that has always fascinated researchers who worked on the pyramids of ancient Egypt. The three largest, those of Cheops and from Kephren in Giza and the red pyramid in Dahshur, are perfectly aligned with the four cardinal points – that is, each of the four corners of their base points perfectly in a direction (north, south, east, west), somewhat like a compass.
But how did the Egyptians manage to achieve such precision in their construction more than 4,000 years ago and without any modern technology? ScienceAlert returns to theory engineer and archaeologist Glen Dashthat could answer this question.
“The builders built the great pyramid of Giza aligned with the cardinal points with an accuracy of more than four minutes of arc or a fifteenth degree”the researcher explained in a study from 2017† All three pyramids have the same flaw: they are rotated slightly counterclockwise from the cardinal points.
Many hypotheses have been put forward to understand how the Egyptians accomplished this feat. Some have suggested the use of the shadow of the sun, others that of the evening star. For Glen Dash, they may have used the autumnal equinox, one of the two times of the year when the length of the day equals that of the night.
The “Indian Circles” method
The hypothesis of using the equinox as an alignment method had long been discarded because it was considered too imprecise. But the researcher puts forward the idea that with a rod called “leprechaun”, it is actually very likely. He experienced it himself during the autumnal equinox of September 22, 2016.
The technique is said “Indian Circles”† Take a stick. At regular intervals, mark the end of the shadow cast by it with a dot. Using a rope attached to a stick, select two points of the curve thus created to connect them. You get an almost perfect line from east to west.
Animation of the Indian circles method. † The Journal of Ancient Egyptian Architecture
There is no evidence to confirm the technique used at the time, it is all guesswork. But some are more likely than others, and this is one of the most consensual. To back this up, Glen Dash has also argued that the margin of error is very slightly counterclockwise, just as we see for the three pyramids.
In addition, the Egyptians only had to count 91 days from the summer solstice to find the equinox, but also and above all to hope for clear weather.
