Researchers have spent centuries wondering just how the Ancient Egyptians managed to build the pyramids, and in particular, how they managed to build and align them so accurately and with such precision. A new theory, published in The Journal of Ancient Egyptian Architecture, suggests that those who built the pyramids used the autumnal equinox to manage this incredible achievement.The ‘Indian circle’ methodThe four angles of the Great Pyramid of Giza are surprisingly accurate and almost perfectly aligned with the four cardinal points. The three pyramids themselves are also aligned with each other in almost perfect proportions. Although nowadays it is possible for us to observe this by using drones and satellite data, at the time, this wouldn’t have been such an easy feat.In 2018, archaeologist and engineer Glen Dash proposed a simple yet elegant hypothesis: the Egyptians used the autumnal equinox to establish their measurements using a gnomon (a vertical rod used to track the movement of the sun on the equinox).Using a series of measurements taken from the equinox on 22nd September 2016, Dash managed to demonstrate that the so-called ‘Indian circle' method allowed them to obtain the orientation of the cardinal points with incredible accuracy.From one rod to a huge pyramidUsing this gnomon, it would have been possible to follow and trace the trajectory of the sun across the sky by tracking the regular shadows projected by the rod from the sun. Once these shadows had formed a smooth curve, all the Egyptians would have needed to do is draw a circle with the gnomon at its centre and mark the two points of intersection between the circle and the curve. Then, they would have needed to draw a straight line from one point to another and they would have a line travelling from east to west (or vice versa), provided that their measurements were taken during the equinox.(For a visual representation of this method, click here)The error margin with this method, as measured by Dash, proves to perfectly coincide with the slight error of one-fifteenth of a degree which has been identified in the orientation of all three of the pyramids. Obviously, this discovery doesn’t prove that this was the technique employed by the Egyptians with certainty, but it nevertheless gives us an area to study that is definitely not lacking in interested parties.