There are several mysteries that wrap the Great Pyramids of Giza such as how they were built without modern technology. But one particular secret captivated Glen Dash, an archaeologist and engineer. He wanted to know how the Egyptians were able to align the pyramids perfectly with a margin of error that is rotated slightly counter-clockwise from the cardinal points. Several theories on how this was done exist however, Dash has a much simpler method which he thinks could explain the phenomenon.
His recent research suggests that the Egyptians roughly 4,500 years ago could have used the autumnal equinox to achieve perfect alignment.
The equinox is regarded as the moment twice a year when the plane of Earth's equator passes through the centre of the Sun's disc, and the length of day and night are pretty much equal.
Previously equinox measurements had been overlooked as a possible alignment method, as it was assumed it wouldn't provide enough accuracy.
But Dash's latest work show that there's a way this could have worked - using a rod known as a gnomon.
(Image credit: Isabella Juskova/Unsplash)