Ancient Egyptian star clocks

Diagonal star clock ( Middle Kingdom )

Ancient Egyptian star clocks were used for astronomical time measurement in ancient Egypt . The model of the diagonal star clock , documented for the first time in the first interim period , used the acronychic culminations and acronychic star sets as a time measurement criterion for the dean stars in addition to the well-known instruments of the heliacal rise . The individual night hour determined in this way had a different length in contrast to the Ramesside star clock that followed later. In addition, the deans, including the associated dean stars, acted as the basis of calculation for the diagonal star clock.

The Ramesside Sternuhr, on the other hand, was based on hour stars without an explicit decan assignment. In addition, a 13th night hour was introduced, which enabled a more precise time measurement. The acronymic criteria used in the diagonal star clocks were embedded in the new system of hour stars. The innovations of the Ramesside star clock were not able to establish themselves in the long term, however, as the historical basis was missing due to the extended hour division compared to the twelve-hour system of the diagonal star clock, which was traditionally used up to the Greco-Roman times . In addition, the Ramessid star clock was not compatible with the mythology of the Amduat .

Diagonal star clocks

The term diagonal star clock refers to linear algebra , in which the main and secondary diagonals mark imaginary lines that run diagonally from top left to bottom right through the Egyptian calendar scheme and thus show the migration of the Dean stars through the respective weeks.

Diagonal star clock EA47605 : idealized ancient Egyptian calendar (division of the deans for the respective decades)
1. P 1	21. A 4	11. A 4	1. A 4	21. A 3	11. A 3	1. A 3	21. A 2	11. A 2	1. A 2	21. A1	11. A 1	1. A 1
13	12	11	10	9	8th	7th	6th	5	4th	3	2	1
14th	13	12	11	10	9	8th	7th	6th	5	4th	3	2
15th	14th	13	12	11	10	9	8th	7th	6th	5	4th	3
16	15th	14th	13	12	11	10	9	8th	7th	6th	5	4th
17th	16	15th	14th	13	12	11	10	9	8th	7th	6th	5
18th	17th	16	15th	14th	13	12	11	10	9	8th	7th	6th
19th	18th	17th	16	15th	14th	13	12	11	10	9	8th	7th
20th	19th	18th	17th	16	15th	14th	13	12	11	10	9	8th
21st	20th	19th	18th	17th	16	15th	14th	13	12	11	10	9
22nd	21st	20th	19th	18th	17th	16	15th	14th	13	12	11	10
23	22nd	21st	20th	19th	18th	17th	16	15th	14th	13	12	11
24	23	22nd	21st	20th	19th	18th	17th	16	15th	14th	13	12
25th	24	23	22nd	21st	20th	19th	18th	17th	16	15th	14th	13

discovery

Coffin of the night

The Egyptologist Ludwig Borchardt was first able to analyze the methods of ancient Egyptian timekeeping based on the fragments and coffin fittings he found. He noticed early on that time measurement in ancient Egypt was based primarily on astronomical observations.

More precise calculations in astronomy led to improved interpretations and possibilities to assign the information on the diagonal star clock to the time of its creation. The first evidence in the form of decorations can be found in the Middle Kingdom. During this time, they are usually on the underside of the coffin lid. The oldest documented diagonal star clocks come from the 9th dynasty . The diagonal star clock on the coffin lid no. 9 can be dated to the reign of Mentuhotep II in the 11th dynasty .

Mentions in the pyramid texts make the diagonal star clocks likely to be used even before the beginnings of the Old Kingdom , but this has not yet been proven. Recent studies have shown that in the Old Kingdom the deans were arranged according to the heliacal staircases and were based on the “ classical image of the sky ”. In the Middle Kingdom, the culminating deans took the place of the “rising deans”. This system-related re-evaluation resulted in the new order of the dean's stars in the coffin texts .

Locations and assignment of the data

The coffins with diagonal star clocks found come from Assiut , Thebes , Gebelein and Aswan . Different arrangements cannot be seen. These circumstances led to the realization that the information on the diagonal star clocks indicates an idealized calendar. Other astronomical records with calendar reference point to the places Memphis and Heliopolis , which is why the information on the diagonal star clocks is most likely based on the 30th parallel .

In the oldest documents from the Middle Kingdom, the heliacal rise of the star Sothis dates back to the twelfth hour of the night as the 18th dean, which corresponds to the 21st Peret II . The Sothis date confirms the content of the coffin texts, according to which the dean ascents determined the respective hours. The later dating connection with the culmination was demonstrably not used at this time, as the calendar information would then no longer correspond to the actual ascents.

functionality

The zodiac signs from Dendera

Otto Neugebauer , Richard Anthony Parker and Christian Leitz proved that the methods of calculating the dean's star of the Greco-Roman times and the Middle Kingdom did not correspond. In the first case, the twelve signs of the zodiac from Dendera , which had already been introduced, served as the basis, which is why the division of the 36 deans and their night hours was based on the ecliptic . In the Middle Kingdom there was neither knowledge of the ecliptic nor the basis of the twelve signs of the zodiac. The functional principle of the diagonal star clocks was therefore based on a different basis.

The life cycle of the deities and dean stars was recorded in the calendar on the images and decorations of the graves . Together with the instrument of the shadow clock , the Egyptians divided the day into the twelve hours of the day and the twelve hours of the night , the length of the day hours depending on the position of the sun during the day. The night hours were divided into equal time units, the duration of which was adapted to the respective season . The night thus had twelve individual periods of equal length, which, however, no longer matched those of the following day.

The dean stars always indicated the end of the respective hour; For example, the heliacal rise of Sirius, according to the division of the diagonal star clock, always took place at the end of the twelfth hour of the night, ideally as the 18th dean star. Christian Leitz refers to the contradicting assumptions of Otto Neugebauer and Richard Anthony Parker, who, contrary to their own definition, equated every night hour of the diagonal star clocks with 10 ° of the ecliptic. The associated calculations in connection with the ecliptic are based on a non-existent basis and therefore do not apply.

Dean stars

In Egyptian astronomy , the year of the Egyptian calendar was divided into 36 weeks of ten days each. The missing five days made up the small year . The weeks were assigned dean stars , each ten days apart with their heliacal rise, giving the 36 weeks their names.

Division of the sky

The sky is divided into hieroglyphs
Middle realm	Sebau-en-pet Sb3w-n-pt Stars of Heaven
New kingdom	Sebau-baktiu Sb3w-b3k.tjw Working stars

Between the first heliacal rising and the acronychic culminating dean star, which makes the first hour of the night , there are twenty dean stars. The dean stars of the sky (sebau-en-pet) had fixed positions in the sky.

Eight dean stars are always in the east and symbolize the birth stars (meset) , nine dean stars represent the dying stars ( scheni-duat ) in the west, while twelve dean stars in the middle of the sky as working dean stars ( Baktiu) are positioned.

Underworld

In the underworld (realm of the dead) there were seven dead stars (sha-tuat). The dead stars had no special tasks, but slept with the dead until the next rebirth.

Ramesside star clocks

16. Achet I ( Thoth ) in the tomb of Ramses VI.

The four surviving specimens from the graves of Ramses VI., Ramses VII. And Ramses IX. could be put together to a largely complete version. A Ramesside star clock contains 24 tables, one each for the first and 16th day of the month of the twelve months of the ancient Egyptian calendar year. The individual table is divided into 13 hour lines, which stood for the period from sunset to sunrise . The first line symbolized the beginning of the night , which began right after sunset. Lines two to 13 represented the end of the twelve hours of the night.

The individual hour line contains three entries: hour, star name and position. The stars listed either belonged to an ancient Egyptian constellation or represented single stars. The Ramesside star clocks contained a total of 47 different stars. The position information related to the seven possible constellations right shoulder , right ear , right eye , middle , left eye , left ear and left shoulder . The middle position stood for the meridian ; the other six details related to the position east and west of the meridian.

Dating of the Ramesside star clocks

The meridian is shown as an orange circle.

Based on the constellations described in the Ramesside star clocks, the Egyptologists of the 19th century recognized that the information relates to a point in time between 1500 and 1450 BC. Need to relate. Otto Neugebauer and Richard Anthony Parker, who confirmed this period, attempted to assign the respective stars. After a detailed analysis, both Egyptologists came to the conclusion that an exact identification of the individual star positions and thus a more precise dating was not possible.

Christian Leitz was the first Egyptologist to deal in detail with the statements made by Otto Neugebauer and Richard-Anthony Parker regarding the Ramesside star clocks. His research results show that some star assignments were incorrect and therefore an exact chronological framework could not be created. Since Seba-en-Sah , the main star of the ancient Egyptian constellation Sah , has now been reliably identified and Seba-en-Sah is also included in the ceiling depictions in the grave of Senenmut ( TT353 ), it was possible to assign it to the exact day. In the tomb of Senenmut it is noted that Seba-en-Sah culminated at midnight on 23 Achet III . The constellations mentioned in the tomb of Senenmut refer to the observation site Memphis as in other ancient Egyptian sources .

Rolf Krauss , who postulated the hypothesis of changing observation sites , rejects an identification of Seba-en-Sah with Rigel because Elephantine is the preferred observation site in his published analyzes . An acceptance of the equation of Seba-en-Sah with Rigel would mean that his concept would be invalid. In the Ramesside star clocks, which were only made about three centuries later, the unchanged information from the tomb of Senenmut reappears, although the star positions in the ancient Egyptian calendar had shifted by more than two months. Astronomical calculations showed that the midnight culmination of Seba-en-Sah in connection with the other stellar dates was only for the years 1463/1462 BC. BC is to be reconciled with the ancient Egyptian calendar and the observation site Memphis.

Ancient Egyptian calendar of the Ramesside star clocks in 1463/1462 BC. Chr.
blackboard	Ancient Egyptian month	1st day of the month ( Gregorian calendar )	16th day of the month (Gregorian calendar)
1 + 2	Achet I 1463 BC Chr.	August 11th to 12th	August 26-27
3 + 4	Achet II 1463 BC Chr.	September 10-11	September 25-26
5 + 6	Achet III 1463 BC Chr.	October 10-11	October 25-26
7 + 8	Achet IV 1463 BC Chr.	November 9-10	November 24th to 25th
9 + 10	Peret I 1463 BC Chr.	December 9-10	December 24th to 25th
11 + 12	Peret II 1462 BC Chr.	January 8th to 9th	January 23rd to 24th
13 + 14	Peret III 1462 BC Chr.	February 7th to 8th	February 22nd to 23rd
15 + 16	Peret IV 1462 BC Chr.	March 9-10	March 24th to 25th
17 + 18	Schemu I 1462 BC Chr.	April 8th to 9th	April 23rd to 24th
19 + 20	Schemu II 1462 BC Chr.	May 8th to 9th	May 23rd to 24th
21 + 22	Schemu III 1462 BC Chr.	June 7th to 8th	June 22-23
23 + 24	Schemu IV 1462 BC Chr.	July 7th to 8th	July 22-23

literature

• Christian Leitz : Ancient Egyptian star clocks . Peeters, Leuven 1995, ISBN 90-6831-669-9
• Sarah Symons: A Star's Year: The Annual Cycle in the Ancient Egyptian Sky . University of Leicester, 2007, le.ac.uk (PDF)
• Alexandra von Lieven : The sky over Esna - A case study on religious astronomy in Egypt using the example of the cosmological ceiling and architrave inscriptions in the temple of Esna . Harrassowitz, Wiesbaden 2000, ISBN 3-447-04324-5
• Alexandra von Lieven: Floor plan of the course of the stars - the so-called groove book . The Carsten Niebuhr Institute of Ancient Eastern Studies (among others), Copenhagen 2007, ISBN 978-87-635-0406-5 .

Web links

• Ancient Egyptian diagonal star clock

Individual evidence

1. ^ Sarah Symons: A Star's Year: The Annual Cycle in the Ancient Egyptian Sky. 2007, p. 3.
2. ↑ Alexandra von Lieven: Plan of the course of the stars. Copenhagen 2007, p. 43.
3. ↑ Siegfried Schott: Egyptian fixed data (= . Academy of Sciences and Literature (Mainz, Germany) .; treatises of Humanities and Social Sciences class ) .Verlag the Academy of Sciences and Literature, Mainz / Wiesbaden 1950, p.25.
4. ↑ Christian Leitz: Ancient Egyptian star clocks. Leuven 1995, p. 74.
5. ↑ Christian Leitz: Ancient Egyptian star clocks. Leuven 1995, p. 75.
6. ↑ Christian Leitz: Ancient Egyptian star clocks. Leuven 1995, p. 73.