Clive Ruggles


… is the study of beliefs and practices relating to the sky in the past, especially in prehistory, and the uses to which people's know- ledge of the skies was put.


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Basic declination calculator


by Andrew Smith

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Springer Handbook (2014):


Ocarina Books publishes and distributes books relating to archaeo- and ethnoastronomy



This list of my books and selected papers and articles contains links and downloadable copies where available.

New orientation data for the Giza Plateau, Egypt

A paper presenting new basic data concerning the orientation of the three great pyramids and associated structures on the Giza Plateau has appeared in the August 2014 issue of Journal for the History of Astronomy.



The great pyramids of the pharaohs Khufu (Cheops), Khafre (Chephren) and Menkaure (Mykerinos) have attracted a huge amount of astronomical interest over the years, both scholarly and popular. Less attention is usually given to the broader context of structures on the Giza Plateau: the three pyramid complexes themselves contain numerous smaller pyramids and mastabas (rectangular tombs), as well as mortuary temples, causeways and valley temples.

Ever since Flinders Petrie undertook a theodolite survey on the Giza plateau in 1881 and drew attention to the extraordinary degree of precision with which the three colossal pyramids are oriented upon the four cardinal directions, there have been a great many suggestions as to how this was achieved and why it was of importance. It is all the more surprising, then, that there have been remarkably few attempts to reaffirm or improve on the basic survey data concerning the primary orientations.

This paper presents the results of a week-long Total Station survey undertaken by Erin Nell and Clive Ruggles during December 2006 under the auspices of the Giza Plateau Mapping Project. Its principal aim was to clarify the basic data concerning the orientation of each side of the three large pyramids and to determine, as accurately as possible, the orientations of as many as possible of the associated structures. The principal difference between this and all previous surveys is that it focuses upon measurements of sequences of points along multiple straight and relatively well preserved structural segments, with best-fit techniques being used to provide the best estimate of their orientation, as opposed to simple triangulation between directly identified or extrapolated corners.

While our results do not directly challenge the idea that circumpolar stars in the north were used to determine the primary orientation of the largest pyramids, they challenge some of the assumptions upon which particular proposals were based. In particular, our results suggest that there is only a very slight difference in orientation (≈0.5 arc minutes) between the north-south axes of Khufu’s and Khafre’s pyramids. Also, the sides of Khafre’s are more perfectly perpendicular than those of Khufu’s, and the east-west axis is closer to true cardinality than the north-south one in both cases. The broader context of associated structures suggests that the east-west orientation in relation to sunrise or (in one case) sunset may have been a, or even the, key factor in determining their orientation in many cases.

The paper “The Orientations of the Giza pyramids and associated structures” by Erin Nell and Clive Ruggles appeared in the August 2014 issue of Journal for the History of Astronomy.


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Astronomical heritage

Portal to the Heritage of Astronomy

Read more on the UNESCO–IAU Portal to the Heritage of Astronomy and about astronomical heritage in general

Free downloads

ICOMOS–IAU Thematic Studies on Astronomical Heritage

No. 1 (2010): See here for more information or click here to download a copy directly (46 Mb)

No. 2 (2017): See here for more information or click here to download a copy (19 Mb)


Astronomical World Heritage


Download a copy of an article published in A&G (Aug 2019 issue)

Stonehenge and Ancient Astronomy


Download a copy of the Royal Astronomical Society’s factsheet

Alice Ruggles Trust

If you are looking for things related to Alice and/or information about stalking, please visit the Alice Ruggles Trust website

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