Astro-geodesy and the Planological Infrastructure of Egypt

Definition of the subject:

Based on a geodetic Observation-line between certain locations in ancient Egypt, some dates of observation of the heliacal rising of the star Sirius have been calculated and are presented here.
The calculated day of observation at a certain parallel of latitude at a certain location (fixed point, for instance gnomons) supports the thesis that a form of triangulation determined the infrastructure of pre-, proto- and historic Egypt. Obviously, the observation of this astronomical phenomenon was of great importance. In the course of many millennia, the selection of points that enabled a precise observation to be made on a specific day of the year had to be amended as a result of the earth’s precession and the proper motion of the star Sirius. The importance of these specific locations disappeared in the process of time and as a consequence, new settlements were established elsewhere, along the river Nile. This process repeated itself throughout history.

Example 1:

The heliacal rising of the star Sirius at El Badari
A star map, created by Skyglobe 3.6, shows the heliacal rising of the star Sirius at a given date. We set the star map for July 13th (Julian Calendar) in the year 4,501 BC, 04h00 AM, over the prehistoric agglomerated settlements Deir Tasa and El Badari. The heliacal rising of Sirius occurred on IV SMW 30 (July 13), approximately 50 minutes before sunrise. The Arcus Visionis and the critical depth of the sun below the true horizon was 9.40, occurring precisely at the upper limit of the critical height of the sun (lower limit 8.534 -8.567, upper limit 9.378 – 9.411). Hence, a ‘first visible rising’ of Sirius did indeed take place shortly before sunrise. This result fits perfectly and confirms the earlier study and the solid conclusions in an article which emeritus Prof. G.W. van Oosterhout wrote on this subject (Discussions in Egyptology; DE 24).

Example 2:

‘Thronstätten’, and the parallels (latitude) of the prehistoric capitals
The settlements in Upper and Lower Egypt that served as observation posts (Thronstätten: Hieraconpolis and Buto) became the prehistoric capitals of Egypt; the geographical latitudes of these two locations are separated by 365 minutes of arc. After the reign of the third Dynasty, a new dual set of observation posts was established. In the course of the centuries, the imaginary line that first ran from south of Edfu to Saïs/Xoïs was later on, during the reign of the fourth Dynasty, reset to extend from Philae to Heliopolis. In all cases, the two locations are separated by 365 minutes of arc. Hence, the Egyptians were aware of the earth’s precession and they observed its effect. The remarkable discovery of this correspondence with the length of the solar year became the foundation for my study of the infrastructure of ancient Egypt.

General remarks:

Triangulation is a method used to measure distances. Starting from a known geographic base line and with the help of clearly visible points or existing locations in the landscape, a network is constructed, consisting of triangles with sides of fixed lengths. The ancient Egyptians developed a slightly different system. Their method consisted of making observations at certain chronological intervals from certain points along a geodetic line between specific locations, which enabled them to measure both time and distance.
This technique can also be found in their hieroglyphic script, especially in the geometrical hieroglyph M44 for the star Sirius (isosceles triangle).

One of the frustrating puzzles concerning the astronomical chronology of Ancient Egypt exists in the search for locations where the first splendid visibility of the heliacal rising of the star Sirius was observed.
This is, amongst others, a consequence of the loss of ancient sources and of the stultifying, yet absolutely erroneous opinion of Prof. Otto Neugebauer that “the Egyptian astronomy had much less influence on the outside world for the very simple reason that it remained through all its history on an exceedingly crude level”. Further on, he says: “an exception is their intelligent calendar which ever existed in human history. Their year consists of 12 months of 30 days each and 5 additional days at the end of each year and the division of the day into 24 hours.”

Authentic source material and thorough examination of texts have, until now, been the foundation which scientific analysis is based on. Does this mean that we should not consider alternative possibilities (technical disciplines) in our efforts to explain their astonishing precision? In point of fact, texts exist which focus on the use of geometry and geodetic techniques. The Egyptians applied this kind of knowledge to plan and apportion their land, using the observation of the heliacal rising of the star Sirius as their starting-point.The planned division of their infrastructure, which was based on astronomy (the first splendid visibility of the star Sirius), provided their culture with a fundamental background.

After all, the heliacal rising of the star Sirius was related to the annual rising of the water of the Nile and its subsequent flooding, which resulted in the fertilization of their land. Its vital significance is obvious, and it is hardly surprising that they based their calendar on this phenomenon. Indeed, my investigations prove that the Egyptian tradition exerted a highly beneficial influence on Hellenistic astronomers, which is documented by their use of the Egyptian calendar.

Generally, the starting-point is that the observation of the heliacal rising of Sirius in the Nile Valley proceeds from the south to the north, with a slowing down of approximately one day per degree in geographic latitude (see also the astronomical tables of Baehr). However, my investigations do not confirm Baehr’s tables. On the contrary, the interval between the first observation of the heliacal rising in the south and the last observation of this phenomenon in the north changed in the course of millennia from nine to eight, then to seven, to six, and after 1,000 BCE (Late Period) down to five days. Before 1,000 BCE,­ considerable deviations must be taken into account. The gradual difference in intervals is due to the change in declination of Sirius, which in turn is caused by the precession. This important difference was undoubtedly registered by the Egyptians.

A further predicament concerns the beginning of an Egyptian calendar-day and the moment of transition from one day to the next. Several texts mention the rising of Sirius taking place in the twelfth hour of the night. Hence, a twenty-four hour period was divided into twelve hours of daytime and twelve hours of nighttime. This indicates that the new day started at sunrise. Around New Year’s Day, the observation of the heliacal rising of the star Sirius occurred approx. 55 to 60 minutes before sunrise on the eastern horizon.

As the calendar system of the Egyptians was based on a Sirius period of 1460 years, the following three periods of that duration can be distinguished: from 4,242 to 2,782 BCE, from 2,782 to 1,322 BCE, and from1,322 BCE to 139 CE. Since 1927 (Schoch and Ingmar), we know that these Sirius periods are not of identical length: 1457/1456 years is a more accurate figure. Therefore, instead of working with Sirius periods, it is advisable to calculate the dates of the heliacal rising of Sirius by means of the critical sun elevation (Arcus Visionis) of 9.41 at a specific location. Under these conditions, first splendid visibility is an empirical fact. For the purpose of this study, we will use the Observation-line between Hieraconpolis and Buto for the period from 4,242 to 2,782 BCE.

Tables of the optimum latitude for the point of observation and proportional division of the Observation-line:
(calculations in cooperation with G.W.van Oosterhout)

Before ca. 4,501 BCE to 4,242 BCE:

07-09-4242 v.C24°48 N
07-10-4242 v.C25°32 N
07-11-4242 v.C26°15 N
07-12-4242 v.C26°57 N (El Badari/Hemamieh)
07-13-4242 v.C27°38 N
07-14-4242 v.C28°20 N
07-15-4242 v.C29°00 N
07-16-4242 v.C29°40 N
07-17-4242 v.C30°19 N (Merimde)
07-18-4242 v.C30°58 N
07-19-4242 v.C31°36 N

Although the figures in this survey unnecessarily accurate, they do present us with the latitude of two extremely important prehistoric settlements. Both locations El Badari/Hemamieh and Merimde, are situated precisely on the parallel in question.

In prehistoric times, a prototype of the Observation-line between El Badari and Gizeh may have been developed initially in conjunction with the latitude of the following settlements. The locations are situated precisely on the latitudinal parallel in question.

Table from ca. 4,500 to ca. 3,800 BCE:

LocationJulian dateArcus VisionisCoordinate of Latitude
El Badari07-139.40 - 9.2027°00 N
Sjeik Atiya07-149.40 - 9.4027°31 N
Zawjet el Amwat07-159.80 - 9.4028°03 N
El Kom el Ahwar Saw.07-1610.00 - 9.7028°34 N
Maiyana07-179.70 - 10.0029°05 N
Tarchan (Girza)07-1810.00 - 9.6029°30 N
Gizeh07-199.50 - 10.2030°00 N

The following observation tables show the three consecutive Sirius periods, specifying location, Julian date, Arcus Visionis, latitude of the specific location and the proportional division of the Observation-line.

Obviously, the following three tables are average, static and are merely presented as an introductory guideline.

Table of the 1st Sirius-period:

From 4,242 – 2,782 BCE; Observation-line Hieraconpolis/Buto:

LocationJulian dateArcus VisionisLatitudeProportional
Hieraconp.07-10-4242 BC9.84225°06 N25°06 N
Khizam07-11-42429.89425°46 N25°47 N
Thinis07-12-424210.03026°20 N26°27 N
Assiut07-13-42429.90627°11 N27°08 N
Hermopolis07-14-42429.98927°47 N27°48 N
El Kom Ahmar07-15-42429.91428°34 N28°29 N
Heracleo. M.07-16-424210.04029°05 N29°10 N
Memphis/Djoser07-17-42429.89829°50 N29°50 N
Ternuthis07-18-42429.99530°26 N30°31 N
Buto07-19-42429.85331°12 N31°12 N

Table of the 2nd Sirius-period:

From 2,782 – 1,322 BCE; Observation-line Philae/Elefan./Heliopolis:

LocationJulian dateArcus VisionisLatitudeProportional
Philae/Elefan.07-10-2782 BC9.37324°03 N24°03 N
Edfu07-11-27829.42124°59 N24°48 N
Tod07-12-27829.67825°35 N25°32 N
Thinis07-13-27829.75226°20 N26°18 N
Assiut07-14-27829.76827°11 N27°04 N
Hermopolis07-15-27829.96927°47 N27°49 N
El Kom el Ahmar07-16-278210.02728°34 N28°35 N
Atfih07-17-27829.95829°25 N29°21 N
Heliopolis07-18-278210.05130°08 N30°07 N
Busiris07-19-27829.99730°55 N30°52 N

Table of the 3rd Sirius-period:

From 1,322 BCE – 139 CE; Observation-line Philae/Elefan./Heliopolis:

LocationJulian dateArcus VisionisLatitudeProportional
Philae/Elefan.07-12-1322 BC9.56824°03 N.24°03 N.
Hieraconpolis07-13-13229.64125°06 N.25°03 N.
Thebe/Denderah07-14-132210.13925°42 N.25°56/26°08 N
Assiut07-15-13229.55927°11 N.27°05 N
Hebenoe07-16-13229.62728°03 N.28°06 N
Heracleo. M.07-17-13229.55329°05 N.29°07 N
Heliopolis07-18-13229.48130°08 N.30°08 N
Buto07-19-13229.30931°12 N.31°09 N