The astronomical orientation of the pyramids of Egypt


Introduction (1/3)

The Old Kingdom pyramids are part of these architectural wonders whose perfect carrying out does not cease to surprise. Besides their magnificence, they have got a common feature : the alignment of their faces towards the cardinal points. This spatial orientation was quite good achieved by the architects of pharaohs Huni, Snofru, Khufu, Khafre and Menkaure. The deviation of their faces from true east is very small, indeed - smaller than 20 minutes of arc -, compared to the one of Djoser's pyramid, which is close to 3 degrees.


Deviations from true east of eleven Old Kingdom pyramids (1).


Does this mean that the method used to align these sacred monuments improved with time ? Or that the IVth dynasty architects used a method different from that of their predecessors ? It still today remains quite difficult to answer this question. The Egyptian writings telling about the method used to build the sacred monuments facing an astronomical direction are rare indeed, moreover late and formal. They besides are always linked with foundation ceremonies to which Pharaoh had to join (2).

1. The value of the errors in cardinal alignments of these Old Kingdom pyramids were taken from the following articles : Spence, Kate, "Ancient Egyptian chronology and the astronomical orientation of pyramids", Nature Volume 408, Novembre 2000, pages 320-324 and Mathieu, Bernard, "Travaux de l'Institut Français d'Archéologie Orientale en 2000-2001", BIFAO Tome 101, 2001, pages 457-459. The two pyramids of Snofrou, generally termed as "rhomboid" and "red", are part of our sample. Contrarily to Kate Spence, we have attributed to the pyramid of Sahure an error from the east-west alignement equal to 1°53', in order to take into account the displacement of the basis of 1,5°. Finally, the chronology considered is between the "upper" and "lower" chronologies defined by J. Malek, "The Old Kingdom", The Oxford history of Egypt, Oxford, 2000, pages 89-117 and J. Baines, J. Malek, "Egipto : Dioses, templos y faraones", Atlas culturales del mundo, Barcelona, 1988, page 36.
2. Edwards, I.E.S, "The pyramids of Egypt", Penguin Books, 1993, page 248.



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