Reading Babylonian astronomical tablets in Istanbul

24. November 2021, by Mathieu Ossendrijver

In October 2021, the ZODIAC project brought me to Istanbul for an eagerly awaited research visit to the cuneiform collection of the Ancient Orient Museum (Eski Şark Eserleri Müzesi). The Ancient Orient Museum belongs to the Archaeological Museums complex, which is located near the Topkapı palace in downtown Istanbul. The building overlooks Tophanı park, where one can also visit a History of Science museum, apart from admiring its ancient trees and squeaking parrots. The Ancient Orient Museum was designed by a French architect under the guidance of Osman Hamdi Bey – the Ottoman official, scholar, writer and painter, who was the founding father of archaeology and museology in the Ottoman empire.

Ancient Orient Museum (photo by author 2021)
Glazed bricks from Babylon (photo by author 2021)

The purpose of my visit was to study Babylonian astronomical tablets from Uruk. They came to light in 1912/13 during the first excavation campaign of the German Orient Society (Deutsche Orientgesellschaft). How did they end up in Istanbul? In accordance with the regulations of the Ottoman empire, to which Iraq belonged at that time, the finds were divided between Berlin and Istanbul. The 1912/13 campaign was the only one covered by these regulations. World War I brought an end to the German excavations in Iraq and when they were resumed in 1928, the Ottoman empire no longer existed. From then on the finds were sent to Baghdad. In the early 1940s the tablets were catalogued by the German Assyriologist Fritz Kraus, who was then in exile in Istanbul. Kraus identified about 100 astronomical tablets, for the most part small fragments of tables with computed data for the planets, the moon, and the sun – a type of texts known as mathematical astronomy. As it turns out, only very few astronomical tablets from the 1912/13 campaign ended up in Berlin. Most of the astronomical fragments were published by Otto Neugebauer in „Astronomical Cuneiform Texts“ (1955). My own investigation is part of an ongoing project that will result in a new edition and analysis of the Babylonian tablets with mathematical astronomy.

Tablet reading room (photo by author 2021)

Where in Uruk do the tablets come from and who wrote them? The documentation about their findspots is incomplete, but it is believed that they were excavated near the Rēš temple, residence of the Babylonian skygod Anu and his spouse Antu. The fragments date from about 250-160 BCE, when Babylonia was under Seleucid rule. At that time the Rēš was Uruk’s main temple and an important center of Babylonian scholarship, comparable only the Marduk’s temple Esagila in Babylon. The tablets were produced by scholarly priests connected to the Rēš. Originally they were probably stored in one or more libraries within the temple – later excavations uncovered the remains of one such library in the south-eastern gate of the temple complex. For an animated reconstruction of the Rēš during this period see

Fragment from Uruk with lunar positions (photo by author 2021)

What is written on these tablets? Babylonian mathematical astronomy is all about the motion of the planets (Mercury, Venus, Mars, Jupiter, Saturn), the moon and the sun. A defining feature of the computations is that positions (longitudes) are expressed as a zodiacal sign and a number of degrees within the zodiacal sign. Some computations also deal with the distance of a planet or the moon above or below the ecliptic, which is the circle through the center of the zodiac. Babylonian scholars created the zodiacal framework near the end of the fifth century BCE. They named 12 zodiacal signs after nearby constellations, starting with the Hired Man (Aries), and ending with the Tails (Pisces). Each sign was divided into 30 units corresponding to 30 modern degrees of arc. All computations are executed and expressed in the 60-based number system known as sexagesimal place value notation. For instance, 10;0,45 Aries denotes a position in 10 degrees, 0 arcminutes and 45 arcseconds = 10 + 0/60 + 45/602 degrees of Aries. A special sign – the so-called Glossenkeil – was used for indicating vanishing digits („0“) within a number.

            The tables were filled from top to bottom and from left to right like Excel spreadsheets. Having filled the top row with initial values, each column was filled from top to bottom by „updating“ the numbers from one to the next instance of a phenomenon, or from day to day, depending on the type of table. The fragment from Istanbul shown above belongs to a table with daily positions of the moon. By zooming in on a few positions, we can recognize a pattern:

(day) 12: 30;08,40 (Capricorn),

(day) 13: 12;23,50 Aquarius ,

(day) 14: 24;57 (Aquarius),

(day) 15: 7;48,10 Pisces.

On day 12 the moon is said to be in 30;08,40 degrees of Capricorn. This number appears unusual for two reasons. First, it contains an extra „zero“ (Glossenkeil), which was added to indicate that the 30 and the 8 are separate digits and not a single digit 38. Secondly, the position is actually beyond 30 degrees of Capricorn, in the first degree of Aquarius. But this is how the scholars in Uruk usually expressed a position in the first degree of a zodiacal sign. In order to see the promised pattern in the numbers, we compute the differences from day to day:

from day 12 to 13 = 12;15,10 degrees,

from day 13 to 14 = 12;33,10 degrees,

from day 14 to 15 = 12;51,10 degrees.

These differences represent the moon’s daily motion along the zodiac. We can easily see a pattern now, because they increase by 18 in the second digit. The value 0;18 is used throughout the tablet. It is repeatedly added until the moon’s daily motion reaches a maximum, and then repeatedly subtracted until it reaches a minimum, etcetera, resulting in a „zigzag sequence“. Only the positions in the zodiac were written on the tablet, not the zigzag sequence that was used for computing them. The Babylonian scholars also used such zigzag sequences for modeling periodic variations in the motion of the planets and the sun.

The Babylonian evidence for mathematical astronomy is limited to Babylon and Uruk. But some of this knowledge, including the most complex algorithms for computing positions of Mercury or the moon, somehow made it to Greco-Roman Egypt, where they show up in Demotic ostraca and Greek papyri. The project ZODIAC aims to develop a convincing account of this remarkable phenomenon of the cross-cultural transfer, translation and adaptation of Babylonian astronomical methods and the associated astrological practices.

Magic and Astrology: Towards a History of the „Time-lords“ (chronokratores)

25. October 2021, by Michael W. Zellmann-Rohrer

The origins of the „time-lords“ in Greek astrology (chronokratores), rulers of sequential and cyclical periods in a human life whose calculation relates to that of the lifespan, remain to be explained. Our earliest references to them as a cohesive system are in the work of the astrologer Vettius Valens of Antioch, who wrote in the mid-second century CE. With little in the way of introduction, Valens speaks of 129-month periods assigned by turns to the five planets and two luminaries, each of which also takes a subdivision of a fixed length (Sun: 19 months; Moon: 25 months; Mercury: 20 months; Venus: 8 months; Mars: 15 months; Jupiter: 12 months; Saturn: 30 months), during which it has special influence over incidents in the life of the individual. Claudius Ptolemy, in keeping with his more systematic approach, at least situates the chronokratores in relation to the more familiar natal astrology, that is, as a check on the appropriateness of predictions to various stages in a human life, while also developing a more sophisticated system of subdivisions. Hephaestion of Thebes claims ancient Egyptian origins for the system in broad terms, without further specifics.

Fragments of ivory diptych with zodiac signs, Sun and Moon, which could have been used to visualize planetary positions (Roman Period, found at Grand [Vosges], France). Source: Musées Grand Est.

In the mass of original horoscopes in the Greek papyri from Roman Egypt, we have robust evidence for the fact of the practice of astrology but so far disappointingly little detail on how it was practiced. A new attestation of the system of the chronokratores allows us to glimpse one way in which the raw data of the traditional horoscopes, which essentially present the planetary positions at birth, could have been used. That is, these positions would have informed the arrangement of the sequence of chronokratores, which in turn could predict more specific aspects and moments of a person’s life than the general characteristics assigned by the constellations of celestial bodies at birth.

In a forthcoming article in Harvard Studies in Classical Philology, within the framework of the Zodiac project hosted in the Institut für Wissensgeschichte des Altertums, I publish an extensive Greek horoscope on papyrus from the Egyptian city of Oxyrhynchus in the Roman period. But it is a „horoscope“ only in the broad sense: it is surely the work of an experienced astrologer, but it does not in fact tell us anything directly about the moment of a client’s birth, but rather gives detailed predictions for this person’s life, at least as far as early adulthood (where the papyrus breaks off), based on the cycle of the chronokratores. This post focuses on another refraction of the celestial chronokratores „on the ground.“ In a papyrus codex of some 36 folia (PGM IV), probably part of an archive of magical and alchemical manuscripts owned in the region of Egyptian Thebes in Late Antiquity, mixed in among rituals for divine revelation, exorcism, and adjuration of supernatural entities for various purposes, we find an excerpt from what must have been a longer sequence of predictions from the course of the chronokratores in the lifetime of an anonymous person. It would be tempting to place that person in turn somewhere in the textual tradition of this codex: the owner, for whom it was copied (if not in fact the copyist), or the owner of an older manuscript that served as source for part of this compilation and copying? The excerpt begins at the age of 53 years, 9 months, which is precisely the start of the sixth 129-month period of a lifespan. The period as a whole is assigned to Mercury, with subdivisions for the standard lengths of months to Mercury, Venus, the Sun, Mars, the Moon, Jupiter, and Saturn, in that order. For the subdivisions assigned to the Sun, Mars, the Moon, Jupiter, and Saturn, short forecasts are added: in the first, the individual is encouraged to „undertake that which you seek“ (sc. to do; or understand perhaps, „what you are asking about“), and in the rest simply advised whether the time is „good“ or „bad.“

Bibliothèque nationale de France cod. suppl. gr. 574 (PGM IV), f. 10v. Source: / Bibliothèque nationale de France

In this context we can also observe the integration of astrological doctrines, but of the catarchic or judicial as opposed to natal branch, with magic in Egypt of the Graeco-Roman and late ancient periods. This is a ritual handbook in the form of a papyrus book-roll (PGM VII: for images see here) roughly contemporary with the Theban codex. Among contents broadly similar to the latter, we find a lunar calendar for the timing of the sorts of ritual procedures generally found in the codex, structured on the principle of the zodiac: that is, for example, when the Moon is in Sagittarius, it is a good time to make invocations to the Sun and Moon, when it is in Aquarius and Aries, to perform various kinds of love-magic, or when it is in Gemini and Cancer, to undertake rituals to win favor and produce amulets, respectively. This same manuscript also coopts the Greek names of the zodiac signs, along with associated occult names and pictorial signs (charakteres), as talismanic elements to be inscribed in a ritual for obtaining a significant dream in oneiromancy (dream-divination). The appearance of astrology within the magical papyri raises the question, which calls for further study, of the relations between „magicians,“ that is, practitioners of the individualistic, instrumental religion of the rituals attested in handbooks like the two discussed here, and astrologers. Could these two sets of personnel have overlapped in part, or could they have exchanged technological expertise in the form of technical literature?            

The ultimate origins of the chronokratores, as those of not a few other astrological concepts with wide later currency, remain to be elucidated. We hope to shed further light on such questions in the course of the Zodiac project, testing among other things the claim by Hephaestion of Egyptian origins and comparing this system in detail with the idiosyncratic lifetime-periodization of the „Old Coptic Horoscope“ of 95 CE. The implication of the chronokratores and of the zodiac in the complexities of knowledge transfer, and of the wider landscape of religion and culture, in Graeco-Roman and late ancient Egypt already suggests interesting results for the history of knowledge.

Text by Michael W. Zellmann-Rohrer, Freie Universität Berlin, ERC-Projekt „ZODIAC – Ancient Astral Science in Transformation“.

ARTE documentary film “Trésors de Mésopotamie”

The ARTE documentary film „Trésors de Mésopotamie“, respectively „Mesopotamien – Archäologen retten, was zu retten ist“ was broadcasted on Arte on September 25, 2021 with participation of Mathieu Ossendrijver, the Principal Investigator of the ZODIAC project.

Mesopotamia – as it is called because of its location between the Tigris and Euphrates rivers – is in what is now Iraq. The land of Sumer, Babylon, the Gilgamesh epic, the rebel Nimrod and the legendary Tower of Babel: These names still stand for what was once Mesopotamia. In 2014, when the terrorist militia of the so-called Islamic State destroyed the most important archaeological sites of northern Mesopotamia, the ancient culture came back into the public eye. The propaganda video images staged by IS, which show the destruction of cultural treasures, went around the world. The ARTE documentary explores the question of the legacy of this civilization that IS terrorists wanted to destroy forever. Iraqi writer and journalist Jawad Bashara mobilized a group of archaeologists and Iraqi citizens to oppose the planned eradication of these pillars of civilization. In a race against time, Jawad Bashara and his supporters are trying to save the ruins, monuments and works of art spread all over Iraq and to restore them using the latest digital technology.