Babylonian planetary calculation in Greco-Roman Egypt

October 1, 2023 by Thomas Peeters

P. 16511 V

Anybody who is eager to determine the precise position of stars or planets in the sky, can nowadays open their computer and find everything they seek with a few clicks through modern software. In antiquity, this was a little harder. Astronomical data were used in first instance to determine the fate of kings and empires, later also for the construction of horoscopes for private individuals. In the Berlin Papyrus Collection, multiple horoscopes are preserved as well (see for instance the oldest preserved, Greek horoscope on papyrus).

The philosopher Sextus Empiricus (2nd century AD) described in his work Πρὸς ἀστρολόγους “Against the Astrologers” (26-28), how the Babylonians performed the observation of planetary positions during childbirth. An astronomer sat on a mountain peak, whereas an assistant sat next to the woman in labor. When the delivery occurred, the assistant sounded a gong and the astronomer directly noted all relevant observational data. This tale is embellished by fantasy, but does not correspond to reality. Observations were often impossible: not all planets are always visible. For this reason, algorithms were employed to create astronomical tables. The positions in the horoscopes were then computed using the tables.

Part of such a table can be found on the object presented here, a papyrus from Oxyrhynchus in Greco-Roman Egypt. The fragment consists of five columns with black lining and is written in a small, rapid, cursive documentary script from the 1st century AD.[1] The table is broken on the left, bottom and right sides; the upper part however is complete. A second fragment of the same table, which consists of parts of columns 3, 4 and 5, is kept in Oxford. The reverse side, the front side of the papyrus, contains a legal proceeding. After this had lost its relevance, this astronomical table was written on the backside, until this as well had lost its importance and was thrown away. As all papyri from Oxyrhynchus, the papyrus originates from a landfill.

P. 16511 V: “Planetary Epoch Table“,

The third column consists of year numbers, which are represented by the Greek L-shaped ἔτος („year“) sign together with a number. The year numbers usually increase by 1, but sometimes also by 2. Thus, in the first four lines we find the years ιϛ, ιη, ιθ, κ: 16, 18, 19, 20. These are regnal years of Roman emperors, and in line 7 it also becomes clear of which emperors. Here column 3 does not contain a year number, but only Γαίου, which is clarified by the addition of κγ το κ(αὶ) α in column 2, which together means „23, also 1 of Gaius“. The described year is year 23 of emperor Tiberius’ reign, 37 AD, which is also year 1 of emperor Gaius’ (Caligula’s) reign. The remainder of the second column contains horizontal strokes only and, apparently, its function is to separate column 1 from the other columns.[2]

Column 4 contains Egyptian month names in Greek script, with full spellings for short names such as Θωύθ „Thouth“ (line 2), Ἁθύρ „Hathyr“ (line 4) and Τῦβι „Tybi“ (line 5); as well as abbreviated ones for longer names such as Φαῶφ „Phaoph“ for Φαῶφι „Phaophi“ (line 3), and Φαρμο „Pharmo“ for Φαρμοῦθι „Pharmouthi“ (line 8). The ο in Φαρμο is written in superscript to indicate that the word is an abbreviation.

Column 5 always starts with a number between 0 and 29, followed by one or often more numbers. These indicate the days of the month and subsequent fractions of these days in the Babylonian sexagesimal system. This notation clearly results from computation and already shows that we are not dealing with a purely Egyptian table. Another unusual characteristic is the use of day 0, instead of day 30 of the preceding month, in lines 5 and 6.

In summary, each line contains a time entry, with intervals of around 13 months each. This time period is characteristic for the planet Jupiter and analysis based on modern data shows that the denoted dates are moments in which Jupiter is located at its so called first station: the place where the planet’s motion becomes retrograde. The letter α above the table could represent the number 1 and thus refer to this; this interpretation, however, is uncertain.[3] Interestingly, for astronomical calculations the unreformed Egyptian calendar, which does not contain leap days, had been kept in use for a long time, as this calendar was easier for calculation. In everyday life, the reformed Egyptian calendar had been in use for a century and a half already at the time when this papyrus was written.

Most tables of this type did not only contain time entries, but also the related planetary positions, expressed in the zodiacal coordinate system. In this case, these positions were probably included in column 6 and the following. But what were the contents of the first column? It is evident that it contained numbers, but since the beginning is broken off and the numbers are mostly fractions, it is complicated to draw a conclusion. They could be related to another celestial phenomenon of Jupiter, or maybe represent positions of the same phenomenon, but prior to year 16 of Tiberius’ reign. The fact that the table begins arbitrarily with year number 16 without mentioning the name of Tiberius supports the hypothesis that something else may have preceded it.

It was surprising to find tables in Egypt which were created by Babylonian methods. Transferring Babylonian algorithms to Egypt is not trivial: the complicated Babylonian algorithms had to be adapted to the Egyptian calendar and local observations had to be used for the planetary positions due to the change in geographical location. This shows that there was advanced knowledge of Babylonian algorithms in Egypt. The table is also surprisingly accurate: the date never deviates from the phenomenon by more than 2 days, while Jupiter can be seen by observation up to about 10 days before or after the calculated date.[4]


Brashear, W.M. & Jones, A., 1999. An Astronomical Table Containing Jupiter’s Synodic Phenomena, Zeitschrift für Papyrologie und Epigraphik 125: 206-210.

Jones, A. (ed.), 1999. Astronomical papyri from Oxyrhynchus (P. Oxy. 4133-4300a), Volumes I, 145-148, and II, 88-91. Philadelphia: American Philosophical Society.

Britton, J. P., & Jones, A., 2000. A New Babylonian Planetary Model in a Greek Source, Archive for History of Exact Sciences 54/4: 349-373.

[1] Brashear & Jones (1999), 206.

[2] Britton & Jones (2000), 350.

[3] Britton & Jones (2000), 350.

[4] Britton & Jones (2000), 370.

This article was first published on the website of BerlPap – Berliner Papyrusdatenbank, „Object of the month“.

Babylonische Planetenberechnung im griechisch-römischen Ägypten

  1. Oktober 2023 von Thomas Peeters

P. 16511 V

Wer heute die genaue Position von Sternen oder Planeten am Himmel bestimmen will, öffnet seinen Computer und findet mit ein paar Klicks in moderner Software alles, was er sucht. In der Antike war das ein wenig schwieriger. Astronomische Daten wurden zunächst genutzt um das Schicksal von Königen und Reichen zu bestimmen, später auch für die Erstellung von Horoskopen für Einzelpersonen. Auch in die Berliner Papyrussammlung sind mehrere Horoskope erhalten (siehe z.B. das älteste erhaltene, griechische Horoskop auf Papyrus).

Der Philosoph Sextus Empiricus (2. Jh. n. Chr.) hat in seinem Werk Πρὸς ἀστρολόγους „Gegen die Astrologen“ (26-28) beschrieben, wie die Babylonier die Beobachtung der Planetenpositionen bei der Geburt eines Kindes durchführten. Ein Astronom saß auf einer Bergkuppe, während ein Assistent neben der Frau in den Wehen saß. Wenn die Entbindung stattfand, läutete der Assistent einen Gong und der Astronom notierte sofort alle relevanten Beobachtungsdaten. Dies ist eine recht fantasievolle Geschichte, welche jedoch nicht der Realität entspricht. Beobachtungen waren oft nicht möglich: nicht alle Planeten sind immer sichtbar. Deswegen verwendete man Algorithmen, um astronomische Tabellen zu erstellen. Die Positionen in den Horoskopen wurden dann anhand der Tabellen berechnet.

Auf dem hier vorgestellten Objekt, einem Papyrus aus Oxyrhynchus im griechisch-römischen Ägypten, findet sich ein Teil einer solchen Tabelle. Das Fragment besteht aus fünf Spalten mit schwarzen Linien und ist in einer kleinen, schnellen, kursiven dokumentarischen Schrift aus dem 1. Jh. n. Chr. geschrieben.[1] Die Tabelle ist an der linken, unteren und rechten Seite abgebrochen; der obere Teil ist jedoch vollständig. Ein zweites Fragment der gleichen Tabelle, das aus Teilen der Spalten 3, 4 und 5 besteht, befindet sich in Oxford. Auf der anderen Seite, der Vorderseite des Papyrus, befindet sich ein Gerichtsverfahren. Nachdem dieses nicht mehr relevant war, wurde auf der Rückseite diese astronomische Tabelle geschrieben, bis auch sie nicht mehr notwendig war und weggeworfen wurde. Wie alle Papyri aus Oxyrhynchus, stammt der Papyrus von einer Mülldeponie.

P. 16511 V: Astronomische Tafel,

Die dritte Spalte besteht aus Jahreszahlen, die durch das griechische L-förmige ἔτος („Jahr“)-Zeichen zusammen mit einer Zahl dargestellt werden. Die Jahreszahlen erhöhen sich in der Regel um 1, manchmal aber auch um 2. So finden wir in den ersten vier Zeilen die Jahre ιϛ, ιη, ιθ, κ: 16, 18, 19, 20. Dies sind Regierungsjahre römischer Kaiser, und in Zeile 7 wird auch klar, welcher Kaiser. Hier steht in Spalte 3 keine Jahreszahl, sondern nur Γαίου, und in Spalte 2 noch zur Verdeutlichung κγ το κ(αὶ) α, was zusammen „23, auch 1 von Gaius“ bedeutet. Es geht hier um das Jahr 23 des Kaisers Tiberius, 37 n. Chr., was auch das Jahr 1 des Kaisers Gaius (Caligula) ist. Der Rest der zweiten Spalte besteht nur aus horizontalen Strichen und soll offenbar die Spalte 1 von den anderen Spalten trennen.[2]

Spalte 4 enthält ägyptische Monatsnamen in griechischer Schrift, mit vollständigen Schreibungen für kurze Namen wie Θωύθ „Thouth“ (Zeile 2), Ἁθύρ „Hathyr“ (Zeile 4) und Τῦβι „Tybi“ (Zeile 5); sowie abgekürzten für längere Namen wie Φαῶφ „Phaoph“ für Φαῶφι „Phaophi“ (Zeile 3), und Φαρμο „Pharmo“ für Φαρμοῦθι „Pharmouthi“ (Zeile 8). Das ο von Φαρμο ist dabei hochgestellt, um zu betonen, dass es sich um eine Abkürzung handelt.

In Spalte 5 steht immer erst eine Zahl zwischen 0 und 29, dann noch eine oder oft auch mehrere Zahlen. Diese geben die Tage des Monats an, mit anschließenden Brüchen dieser Tage im babylonischen Sexagesimalsystem. Dies ist eindeutig die Folge einer Berechnung und zeigt bereits, dass wir es nicht mit einer rein ägyptischen Tabelle zu tun haben. Ungewöhnlich ist auch die Verwendung des Tages 0, anstelle des Tages 30 des Vormonats, in den Zeilen 5 und 6.

Zusammengefasst enthält jede Zeile einen Zeitpunkt, mit Zeitsprüngen von jeweils circa 13 Monaten. Diese Zeitspanne ist charakteristisch für den Planeten Jupiter, und die Analyse anhand moderner Daten zeigt, dass es sich um Zeitpunkte handelt, in denen sich Jupiter an der so genannten ersten Station befindet: dem Ort, an dem die Bewegung des Planeten rückläufig wird. Der Buchstabe α über der Tabelle könnte für die Zahl 1 stehen und sich somit darauf beziehen, diese Interpretation ist jedoch unsicher.[3] Interessanterweise war für astronomische Berechnungen noch lange Zeit der unreformierte ägyptische Kalender in Gebrauch, d. h. ohne Schalttage, da es einfacher war mit diesem Kalender zu rechnen. Im täglichen Leben war der reformierte ägyptische Kalender bereits seit anderthalb Jahrhunderten in Gebrauch, als dieser Papyrus verfasst wurde.

Die meiste Tabellen dieser Art enthielten neben den Zeitpunkten auch die entsprechenden Positionen der Planeten, ausgedrückt im zodiakalen Koordinatensystem. Diese waren vermutlich in Spalte 6 und den folgenden enthalten. Was stand aber in der ersten Spalte? Es sind deutlich Zahlen, aber da der Anfang abgebrochen ist und es sich hauptsächlich um Bruchzahlen handelt, ist es schwierig, daraus eine Schlussfolgerung zu ziehen. Es könnte sich um Himmelspositionen eines anderen Jupiterphänomens handeln, oder vielleicht um Positionen desselben Phänomens, aber vor dem Jahr 16 des Tiberius. Dass die Tabelle willkürlich mit dem Jahr 16 beginnt, ohne den Namen Tiberius zu erwähnen, spricht für die Hypothese, dass vielleicht etwas anderes vorausging.

Es war erstaunlich, mit babylonischen Methoden erstellte Tabellen in Ägypten zu finden. Die Übertragung der babylonischen Algorithmen auf Ägypten ist nicht trivial: Die komplizierten babylonischen Algorithmen mussten an den ägyptischen Kalender angepasst werden, und für die Himmelspositionen mussten aufgrund der veränderten geographischen Lage lokale Beobachtungen herangezogen werden. Dies zeigt, dass es in Ägypten fortgeschrittene Kenntnisse von babylonischen Algorithmen gab. Die Tabelle ist außerdem erstaunlich genau: das Datum weicht nie mehr als 2 Tage vom Phänomen ab, während man Jupiter bei Beobachtung bis ungefähr 10 Tage vor oder nach dem berechneten Zeitpunkt sehen kann.[4]


Brashear, W.M. & Jones, A., 1999. An Astronomical Table Containing Jupiter’s Synodic Phenomena, Zeitschrift für Papyrologie und Epigraphik 125: 206-210.

Jones, A. (ed.), 1999. Astronomical papyri from Oxyrhynchus (P. Oxy. 4133-4300a), Volumes I, 145-148, and II, 88-91. Philadelphia: American Philosophical Society.

Britton, J. P., & Jones, A., 2000. A New Babylonian Planetary Model in a Greek Source, Archive for History of Exact Sciences 54/4: 349-373.

[1] Brashear & Jones (1999), 206.

[2] Britton & Jones (2000), 350.

[3] Britton & Jones (2000), 350.

[4] Britton & Jones (2000), 370.

Dieser Beitrag wurde zuerst auf der Webseite von BerlPap – Berliner Papyrusdatenbank unter „Stück des Monats“veröffentlicht.

Ein Horoskop für die Freie Universität Berlin nach antiken Verfahren

(For the English version, see previous blog entry)

17. August 2023, Mathieu Ossendrijver und das ZODIAC-Team

In diesem Jahr feiert die Freie Universität Berlin ihren 75. Geburtstag. Das Forschungsprojekt „ZODIAC – Ancient Astral Science in Transformation“ hat dies als Anlass genommen, um die folgende Frage zu stellen: wie würde ein antiker Astrologe das Geburtshoroskop der Freien Universität Berlin bestimmen und ihre Zukunft deuten? Nicht nur die Antwort auf diese Frage ist interessant, auch die Beantwortung an sich liefert interessante Ergebnisse. Denn indem wir die einzelnen Schritte der Berechnung und der Deutung eines Horoskops nach antiken Verfahren rekonstruieren, werden mögliche Lücken in unserem Verständnis dieser Verfahren erkennbar.

Die horoskopische Astrologie entstand im 5. Jh. in Babylonien. Babylonische Gelehrte führten den Tierkreis mit zwölf Zeichen von 30 Grad ein und sie entwickelten eine neue astrologische Lehre, wonach die Zukunft eines Menschen aus den Tierkreispositionen von Mond, Sonne, und der fünf Planeten (Merkur, Venus, Mars, Jupiter und Saturn), die sie zur Zeit der Geburt einnahmen, abgeleitet werden kann. Die Zusammenstellung dieser Positionen wird als Horoskop bezeichnet. Neu an der horoskopischen Astrologie war auch, dass sie von Privatleuten benutzt wurde, und nicht nur von Herrschern, wie dies in der älteren mesopotamischen Astrologie der Fall war.

Die horoskopische Astrologie verbreitete sich von Babylonien aus nach Ägypten und in die griechisch-römische Welt, wo sie sich weiter entwickelte. In griechisch-römischen Horoskopen wird zusätzlich zu den Positionen von Mond, Sonne und Planeten auch der sogenannte Aszendent aufgezeichnet. Der Aszendent ist die Position im Tierkreis, entweder als ganzes Zeichen oder genauer bis zum Grad definiert, die zur Zeit der Geburt am östlichen Horizont aufgeht.

Die Positionen von Mond, Sonne, Planeten und Aszendenten wurden nicht beobachtet, sondern berechnet. Das ist schon daran erkennbar, dass an einem beliebigen Tag nicht alle Planeten sichtbar sind. Die Erstellung eines Horoskopes erforderte also umfangreiche mathematische Berechnungen. Um so erstaunlicher ist es, dass die horoskopische Astrologie sich so erfolgreich von Babylonian aus über die antike Welt verbreiten konnte.

Grundlage für die Erstellung eines Horoskops ist das Geburtsdatum. Als Geburtsdatum der Freien Universität Berlin nehmen wir das Gründungsdatum, 4. Dezember 1948. Da ein griechisch-römisches Horoskop zusätzlich den Aszendenten erwähnt, muss auch die Zeit der Gründung bekannt sein. Die genaue Zeit konnte leider nicht ermittelt werden. Wir haben 11:00 Mitteleuropäische Zeit als hypothetische Geburtszeit angenommen, weil wir dies als eine plausible Zeit für den Gründungsakt einschätzen.

Da es in der Antike unterschiedliche Verfahren gab um ein Horoskop zu berechnen und zu deuten, mussten wir daraus eine Selektion machen. Wir haben uns entschieden für eine babylonische Variante und eine griechisch-römische Variante.

Das Horoskop der Freien Universität Berlin nach modernen astronomischen Verfahren

Im Idealfall müssten alle Positionen nach antiken Verfahren berechnet werden. Da dies sehr aufwendig wäre, haben wir uns dafür entschieden, die Positionen zuerst mit Standardverfahren der modernen Astronomie zu berechnen. Das Ergebnis ist in der folgenden Tabelle zusammengestellt:

Horoskop für die FU Berlin, 4. Dezember 1948 11:00 MEZ

Mond26º Steinbock
Sonne12º Schütze
Merkur8º Schütze
Venus10º Skorpion
Mars6º Steinbock
Jupiter4º Steinbock
Saturn6º Jungfrau
Aszendent26º Steinbock

Die folgende Abbildung zeigt eine Visualisierung des Horoskops (mit Dank an Michael Zellmann-Rohrer):

Berechnung des Horoskops nach babylonischen Verfahren am Beispiel von Jupiter

Wir zeigen jetzt zuerst, wie ein babylonischer Astrologe berechnet haben könnte, dass Jupiter sich am 4. Dezember 1948 in 4º Steinbock befand. Das wurde in zwei separaten Rechenschritten erreicht:

            (1) Berechnung der synodischen Phänomene (Datum und Tierkreisposition). Die synodischen Phänomene Jupiters, die in Babylonien beobachtet und berechnet wurden, sind die Erste Sichtbarkeit, die Erste Station, der Aufgang am Abend, die Zweite Station, und die Letzte Sichtbarkeit. Sie bilden einen Zyklus, der etwa 13 Monate dauert (Fig. 1).

           (2) Berechnung der Tierkreispositionen Jupiters von Tag zu Tag zwischen den synodischen Phänomenen.

Fig. 1 Scheinbare Bewegung Jupiters relativ zu den Sternen im Laufe eines synodischen Zyklus. Bis zur Ersten Station und nach der Zweiten Station bewegt sich Jupiter vorwärts (von rechts nach links); zwischen Erster und Zweiter Station rückwärts (von links nach rechts).

Schritt 1: Berechnung der synodischen Phänomene

Das letzte synodische Phänomen Jupiters, das sich vor dem 4. Dezember 1948 ereignete, war die Zweite Station. Wir berechnen darum, auf babylonische Art, zuerst eine Tabelle mit Zweiten Stationen, ausgehend von einer früheren Instanz dieses Phänomens. Die Babylonier rechneten in einem Zahlensystem das auf 60 basiert (sexagesimal). Zahlen werden als Sequenzen von Stellen 0–59 dargestellt, wobei jede Stelle zu einer nach rechts abnehmenden Potenz von 60 gehört. In Übersetzungen dient ein Komma als Trennzeichen zwischen den Stellen, mit einer Ausnahme: das Semikolon (;) trennt den Teil der Zahl grösser als 1 vom Teil kleiner als 1. Zum Beispiel 17;5,10 = 17 + 5/60 + 10/3600. Der babylonische Kalender der letzten Jahrhunderte v.u.Z. basiert auf der Seleukidenära, wobei Jahr 1 der Seleukidenära = 311/310 v.u.Z. Die babylonischen Monate werden als römische Ziffer abgekürzt. Der 4. Dezember 1948 entspricht dann Tag 2 von Monat IX des Jahres 2259 der Seleukidenära. Die Jahreszahl 2259 würde ein Babylonier als 37,39 schreiben (37 x 60 + 39 = 2259).

Als Anfangswerte für die Tabelle nehmen wir die Zweite Station Jupiters, die Tag 28, Monat VII, Jahr 37,29 (= 2249) der Seleukidenära in 26º Wassermann stattfand. Diese Werte hätte der babylonische Astrologe entweder einem Beobachtungsbericht oder einer existierenden Tabelle entnehmen können. Wir berechnen, ausgehend von der Zweiten Station im Jahr 2249, die darauffolgenden Instanzen der Zweiten Station mit einem babylonischen Algorithmus, der als „System A“ bekannt ist. Auf die Details des Algorithmus können wir hier nicht weiter eingehen. Wir beenden die Berechnung mit der Zweiten Station an Tag 10, Monat V des Jahres 2259 der Seleukidenära, was dem 16. August 1948 entspricht.

Jahr der SeleukidenäraMonatTagTierkreisposition
37,29 (= 2249)VII2926ºWassermann
37,36II 1;2115;50ºJungfrau
37,39 (= 2259)V10;46,3019ºSchütze
Zweite Stationen von Jupiter, berechnet mit dem babylonischen Algorithmus „System A“

Schritt 2: Berechnung der täglichen Position Jupiters seit dem letzten synodischen Phänomen

Im zweiten Schritt wird die Tierkreisposition Jupiters ab seiner Zweiten Station von Tag zu Tag bis zum Gründungstag der Freien Universität Berlin berechnet. Wir benutzen dafür eine babylonische Methode, wonach Jupiter sich mit konstanter Geschwindigkeit entlang der Ekliptik bewegt. Folgende Tabelle zeigt einen Ausschnitt aus der Berechnung:

Jahr der SeleukidenäraMonatTagGeschwindigkeit [º/Tag]Position im Tierkreis
37,39 (= 2259)V100;8,1019ºSchütze
und so weiter
37,39 (= 2259)IX20;8,104;14,40ºSteinbock
Tägliche Positionen von Jupiter bis zum 4. Dezember 1948, berechnet mit einem babylonischen Algorithmus.

Die Berechnung endet an Tag 2, Monat IX, Jahr 37,39 (= 2259) der Seleukidenära, was dem 4. Dezember 1948 entspricht, mit dem Ergebnis: Jupiter war in 4º Steinbock. Auf ähnliche Art und Weise hätte der babylonische Astrologe die Positionen von Mond, Sonne, und der anderen vier Planeten berechnet.

Das Horoskop der Freien Universität Berlin auf einer babylonischen Tontafel

Wie würde das Horoskop aussehen und welche Daten würde es enthalten? Die folgende Abbildung zeigt eine synthetische babylonische Tontafel mit dem Horoskop der Freien Universität Berlin, von Alessia Pilloni nach babylonischen Beispielen angefertigt und beschrieben.

Tontafel mit Horoskop der Freien Universität Berlin in babylonischer Keilschrift (Alessia Pilloni)

Hier folgt, für die Interessierten, die Transliteration der Tontafel:

MU.37.39.KAM ITI.GAN 2


a-lid ina si-ma-ni-šu

sin ina 26 MAŠ₂

šamaš₂ ina 12 PA


dil-bat ina 10 GIR₂

GU₄.UD ina 7 PA


AN ina 5 MAŠ₂

ina E₂ ni-ṣir-tu₄ ša AN

E₂.DUB.BA a-lid

Und hier folgt die Übersetzung:

Jahr 2259, Monat IX, Tag 2,

die Universität zu Berlin

wurde geboren. Zu diesem Zeitpunkt war

der Mond in 27° Steinbock,

die Sonne in 12° Schütze,

Jupiter in 4° Steinbock,

Venus in 10° Skorpion,

Merkur in 7° Schütze,

Saturn in 6° Jungfrau,

Mars in 5° Steinbock.

Im Haus des Geheimnisses des Mars

wurde die Universität geboren.

Deutung des Horoskops nach babylonischen Verfahren

Wie würde ein babylonischer Astrologe das Horoskop deuten? Die Regeln, wonach die zukunft des Neugeborenen aus dem Horoskop abgeleitet wurde sind nur fragmentarisch bekannt. Ein Grund dafür ist, dass die Vorhersagungen nur selten auf dem Horoskop geschrieben wurden. Für bestimmte Konfigurationen von Planeten und Tierkreiszeichen, aber nicht für alle, die im Horoskop der FU auftreten, gibt es Sammeltafeln mit Vorhersageregeln. Es folgen einige Zitate aus solchen Tafeln, zusammengestellt von Marvin Schreiber. Die einzelnen Vorhersagungen sind zum Teil widersprüchlich. Wie ein babylonischer Astrologe daraus eine Gesamtdeutung des Horoskops ableiten würde ist nicht wirklich klar.

Mond, Mars, Jupiter in Steinbock

„Region des Steinbocks: er wird arm, erkranken, sterben“. Diese Regel aus einer Sammlung von Todesvorhersagungen verspricht nicht viel gutes, aber sie ist günstiger als die meisten anderen, wie z.B. „Region der Zwillinge: Tod im Gefängnis“.

Jupiter ist sichtbar, Mars unsichtbar

Das Horoskop erwähnt nicht, ob ein Planet sichtbar oder unsichtbar war. Babylonischen Astrologen konnten aber auch diesen Aspekt berücksichtigen. Am 4. Dezember 1948 war Jupiter nachts sichtbar, während Mars unsichtbar war, weil dieses Datum zwischen Letzter und Erster Sichtbarkeit ist.

„Wenn ein Kind geboren wird, Jupiter aufgeht und Mars untergeht: diesem Mann wird es gut gehen, er wird den Untergang seines Gegners erleben.“ Diese Regel verspricht gutes für die Freie Universität, schlechtes für ihren „Gegner“, der noch zu identifizieren wäre.

Mars in seinem Haus des Geheimnisses

Für jeden Planeten galt ein Tierkreiszeichen als „Haus des Geheimnisses“, ein Konzept, das etwa der „Erhöhung“ (Exaltation) in der griechisch-römischen Astrologie entspricht. Es ist anzunehmen, dass die Präsenz von Mars in seinem „Haus des Geheimnisses“ Steinbock die Wirkung dieses ungünstigen Planeten verstärkt, aber wie sich das auswirken könnte ist unbekannt.

Saturn, Mond, Jupiter und Mars im Trigon (Stier – Jungfrau – Steinbock)

Der Trigonalaspekt (Trigon = Dreieck von Tierkreiszeichen) spielte eine wichtige Rolle in der babylonischer Astrologie. Drei Planeten und der Mond befinden sich im Trigon Stier – Jungfrau – Steinbock. Entsprechende Vorhersagen sind nicht überliefert, aber wahrscheinlich wären diese günstig für das Neugeborene.

Mond, Mars, Jupiter und Saturn im Trigon Stier –Jungfrau – Steinbock
Diagramm zum Trigonalaspekt auf einer babylonischen Tontafel (ca. 200 v.u.Z)

Deutung des Horoskops nach griechisch-römischen Verfahren

Die Regeln, wonach in der griechisch-römischen Welt ein Horoskop gedeutet wurde, sind vergleichsweise gut bekannt aus astrologischen Handbüchern, wie denjenigen von Vettius Valens (ca. 120–175 u.Z.), Firmicus Maternus (300–337 u.Z.), Hephaistion von Theben (5. Jh. u.Z). Die folgenden auf die Gründung der FU zutreffenden Regeln hat Michael Zellmann-Rohrer aus solchen Handbüchern entnommen:

Mars in seiner Erhöhung

Mars im Zeichen seiner Erhöhung, dem Steinbock: „Diplomatie angesichts schwieriger Umstände; Teilhabe an der Affinität des Mars zu feiner Kleidung und Wein.“


Jupiter, Mars, und Mond in Konjunktion: „kluge, mutige Staatsdiener mit vielen Freunden, die aus bescheidenen Anfängen zu großen Dingen aufsteigen, Vertrauen gewinnen und dann ihre Aufgaben übernehmen. Sie erleiden möglicherweise Verluste, erholen sich aber dank göttlicher oder unerwarteter Hilfe.“

Jupiter und Mars in Konjunktion: „Ehre wird nur durch harte Arbeit erlangt“

Jupiter und Mond in Konjunktion: „angesehene Ämter, Entdeckung von Schätzen“.

Sonne und Merkur in Konjunktion: „Flexibilität, Menschenverstand, Urteilsvermögen für Karriere im öffentlichen Leben, Liebe zur Schönheit, Wohltätigkeit, Einweihung in göttliche Lehren, Ausdauer von Widrigkeiten“

Saturn und Merkur im Quadrataspekt

Der Quadrataspekt betrifft Zeichen, die um 90 Grad voneinander getrennt sind. Er hat in der griechisch-römischen Astrologie im Allgemeinen einen negativen Charakter, in diesem Fall: „er wird mit Verwaltungspflichten und Angriffen von Neidern belastet sein.“

Aszendent in Steinbock

„Zuneigung zu Freunden, Klugheit, Glück, reichliche Ressourcen, Kenntnis der Geheimnisse heiliger Riten und fremder Lebensweisen.“

Die 12 Örter

Das Tierkreiszeichen des Aszendenten wurde als 1. Ort bezeichnet, in diesem Fall Steinbock. Von dort aus wurden die anderen 11 Ort gezählt. Damit verknüpft war eine Lehre mit eigenen Vorhersageregeln.

Mond, Mars, Jupiter im 1. Ort: „eine sehr glückliche Karriere, wohlverdiente Fortschritte vor Geschwistern, Ruhm, Tugend und gute Laune. Fortschritt durch brillante Kampagnen, Großzügigkeit, Erwerb von großem Eigentum, das später in Staatskasse übergeht.“

Merkur im 12. Ort: „Intelligenz“

Saturn im 9. Ort: „berühmte Zauberer, Wahrsager, Astrologen, berühmte Philosophen, die oft ihre Haare lang wachsen lassen, Traumdeuter.“

A horoscope for Freie Universität Berlin based on ancient methods

(For the German version, see previous blog entry.)

17. August 2023, by Mathieu Ossendrijver and the ZODIAC-Team

This year Freie Universität Berlin is celebrating its 75th birthday. The research project „ZODIAC – Ancient Astral Science in Transformation“ took this as an opportunity to ask the following question: how would an ancient astrologer determine the birth chart of Freie Universität Berlin and interpret its future? Not only is the answer itself of interest, but even more so the process of answering can yield interesting results, because by reconstructing the individual steps of the calculation and the interpretation of a horoscope according to ancient methods, possible gaps in our understanding of these methods become apparent.

Horoscopic astrology originated in Babylonia in the 5th century BCE. Babylonian scholars introduced the zodiac with twelve signs of 30 degrees and they developed a new astrological doctrine according to which a person’s future is determined from the zodiacal positions of the moon, the sun, and the five planets (Mercury, Venus, Mars, Jupiter, and Saturn) at the time of birth. In its barest form, an ancient horoscope is nothing more than a list of these positions. Another new feature of horoscopic astrology is that it was used by private individuals, and not just by rulers as was the case in older Mesopotamian astrology.

Horoscopic astrology spread from Babylonia to Egypt and the Graeco-Roman world, where it continued to develop. In Greco-Roman horoscopes, in addition to the positions of the moon, the sun and the planets, the so-called ascendant is also recorded. The ascendant is the position in the zodiac, defined either as a whole sign or more precisely to the degree, that rises on the eastern horizon at the time of birth.

The positions of the moon, the sun, the planets and the ascendant were not observed but calculated. This can already be seen from the fact that not all planets are visible on any given day. The creation of a horoscope therefore required extensive mathematical calculations. It is all the more astonishing that horoscopic astrology was able to spread so successfully from Babylonian to the ancient world.

The basis for creating a horoscope is the date of birth. We take the founding date, December 4, 1948, as the date of birth of Freie Universität Berlin. Since a Greco-Roman horoscope also mentions the ascendant, the time of founding must also be known. Unfortunately, the exact time could not be determined. We have assumed 11:00 am Central European Time as the hypothetical time of birth because we consider this to be a plausible time for the founding act.

Since there were different methods of calculating and interpreting a horoscope in ancient times, we had to make a selection from them. We decided on a Babylonian variant and a Greco-Roman variant.

The horoscope of Freie Universität Berlin based on modern astronomical methods

Ideally, all positions would have to be calculated using ancient methods. Since this would be very time-consuming, we decided to first calculate the positions using standard modern astronomical methods. The result is summarized in the following table:

Horoscope for FU Berlin, December 4, 1948 11:00 CET

moon26º Capricorn
sun12º Sagittarius
Mercury8º Sagittarius
Venus10º Scorpio
Mars6º Capricorn
Jupiter4º Capricorn
Saturn6º Virgo
Ascendent26º Capricorn

The following figure shows a visualization of the horoscope (thanks to Michael Zellmann-Rohrer):

Calculation of the horoscope according to Babylonian methods using Jupiter as an example

We now show first how a Babylonian astrologer might have calculated that Jupiter was in 4º Capricorn on December 4, 1948. This was achieved in two separate steps:

            (1) Calculation of synodic phenomena (date and zodiac position). The synodic phenomena of Jupiter that were observed and calculated in Babylonia are First Visibility, First Station, Evening Rising, Second Station, and Last Visibility. They form a cycle that lasts about 13 months (Fig. 1).

            (2) Calculation of the zodiacal positions of Jupiter from day to day between the synodic phenomena.

Fig. 1 Apparent motion of Jupiter relative to the stars over one synodic cycle. Up to the first station and after the second station Jupiter is moving forward (right to left); between the first and second station backwards (from left to right). Between last appearance and first appearance the planet is invisible.

Step 1: Computation of Synodic Phenomena

The last synodic phenomenon of Jupiter to occur before December 4, 1948 was the second station. We therefore, in Babylonian fashion, first calculate a table of second stations, starting from an earlier instance of this phenomenon. The Babylonians used a number system based on 60 (sexagesimal). Numbers are represented as sequences of digits 0-59, with each digit belonging to a right-decreasing power of 60. In translations, a comma is used as a separator between digits, with one exception: the semicolon (;) separates the part of the number greater than 1 from the part less than 1. For example 17;5,10 = 17 + 5/60 + 10/3600. The Babylonian calendar of the last centuries BCE. was based on the Seleucid Era, where year 1 = 311/310 BCE. The Babylonian months are abbreviated as Roman numerals. December 4, 1948 then corresponds to day 2 of month IX of year 2259 of the Seleucid Era. The year 2259 would be written by a Babylonian as 37.39 (37 x 60 + 39 = 2259).

As initial values for the table we take the second station of Jupiter that took place on Day 28, Month VII, Year 37,29 (= 2249) of the Seleucid Era in 26º Aquarius. The Babylonian astrologer could have taken these values either from an observational report or an existing table. Starting with the second station in 2249, we compute subsequent instances of the second station using a Babylonian algorithm known as „System A.“ We cannot go into the details of the algorithm here. We end the calculation with the second station on Day 10, Month V of the year 2259 of the Seleucid Era, which corresponds to August 16, 1948.

year of Seleucid Eramonthdayposition in zodiac
37,29 (= 2249)VII2926ºAquarius
37,39 (= 2259)V10;46,3019ºSagittarius
Second stations of Jupiter calculated using the Babylonian „System A“ algorithm

Step 2: Calculation of the daily position of Jupiter since the last synodic phenomenon

In the second step, the zodiacal position (longitude) of Jupiter is calculated from day to day from that second station up to the founding day of Freie Universität Berlin. We use a Babylonian method for this, according to which Jupiter moves at a constant speed along the ecliptic. The following table shows the first four days and the last four days of the calculation while omitting the intermediate days:

year of Seleucid Eramonthdayvelocity [º/day]Position in zodiac
37,39 (= 2259)V100;8,1019ºSagittarius
et cetera
37,39 (= 2259)IX20;8,104;14,40ºCapricorn
Daily positions of Jupiter up to December 4, 1948, calculated with a Babylonian algorithm.

The calculation ends on day 2, month IX, year 37.39 (= 2259) of the Seleucid Era, which corresponds to December 4, 1948, with the result: Jupiter was in 4º Capricorn. In a similar fashion, the Babylonian astrologer would have calculated the positions of the moon, the sun, and the other four planets.

The horoscope of Freie Universität Berlin on a Babylonian clay tablet

What would the horoscope look like and which data would it contain? The following illustration shows a synthetic Babylonian clay tablet with the horoscope of Freie Universität Berlin, made and described by Alessia Pilloni based on Babylonian examples.

Clay tablet with the horoscope of Freie Universität Berlin in Babylonian cuneiform (Alessia Pilloni)

Here follows, for those interested, the transliteration of the clay tablet:

MU.37.39.KAM ITI.GAN 2


a-lid ina si-ma-ni-šu

sin ina 26 MAŠ₂

šamaš₂ ina 12 PA


dil-bat ina 10 GIR₂

GU₄.UD ina 7 PA


AN ina 5 MAŠ₂

ina E₂ ni-ṣir-tu₄ ša AN

E₂.DUB.BA a-lid

And here is the translation:

Year 2259, Month IX, Day 2,

the University of Berlin

was born. At that time

the moon was in 27° Capricorn,

the sun in 12° Sagittarius,

Jupiter in 4° Capricorn,

Venus in 10° Scorpio,

Mercury in 7° Sagittarius,

Saturn in 6° Virgo,

Mars in 5° Capricorn.

In the House of Secrecy of Mars the university was born.

Interpretation of the horoscope according to Babylonian methods

How would a Babylonian astrologer interpret the horoscope? The rules according to which the future of the newborn was derived from the horoscope are only partially known. One reason is that the predictions were rarely written on the horoscope. For certain configurations of planets and zodiac signs, but not for all that appear in the chart of Freie Universität, there are tablets with predictive rules. Below are some quotes from such tablets, compiled by Marvin Schreiber. The individual predictions are partly contradictory. How a Babylonian astrologer would derive an overall interpretation of the horoscope from this is not really clear.

Moon, Mars, Jupiter in Capricorn

„Region of Capricorn: he becomes poor, falls ill, dies“. This rule from a collection of death predictions does not promise much good, but it is not as bad as most others, such as „Region of the Twins: Death in Prison.“

Jupiter is visible, Mars invisible

The horoscope does not mention whether a planet was visible or invisible. But Babylonian astrologers could also take this aspect into account. On December 4, 1948, Jupiter was visible at night while Mars was invisible because that date is between Last and First Visibility.

„If a child is born, Jupiter rises and Mars sets: this man will prosper, he will see his adversary’s downfall.“ This rule promises good things for Freie Universität, bad things for its „opponent,“ who has yet to be identified.

Mars in his house of secrecy

For each planet one sign of the zodiac was considered to be its „house of secrecy,“ a concept roughly analogous to the „exaltation“ in Greco-Roman astrology. It is likely that the presence of Mars in his „House of Secrecy“ Capricorn will amplify the effects of this unfavorable planet, but how that might play out is unknown.

Saturn, Moon, Jupiter and Mars in trine (Taurus – Virgo – Capricorn)

The trine aspect (= triangle of zodiac signs) played an important role in Babylonian astrology. Three planets and the moon are in the trine Taurus – Virgo – Capricorn. Corresponding predictions have not been handed down, but they would probably be favorable for the newborn.

Moon, Mars, Jupiter and Saturn in trine Taurus – Virgo – Capricorn

Diagram of the trigonal aspect on a Babylonian clay tablet (ca. 200 BCE)

Interpretation of the horoscope according to Greco-Roman methods

The rules by which a horoscope was interpreted in the Greco-Roman world are comparatively well known from astrological manuals such as those of Vettius Valens (c. 120-175 CE), Firmicus Maternus (300-337 CE), Hephaestion of Thebes (5th century CE). From such manuals, Michael Zellmann-Rohrer compiled the following predictions that apply to the horoscope of Freie Universität Berlin:

Mars in its exaltation

Mars in its exaltation, Capricorn: „Diplomacy in the face of difficult circumstances; sharing in Mars‘ affinity with fine clothing and wine.“


Jupiter, Mars, and Moon in conjunction: „clever, courageous civil servants with many friends who rise from humble beginnings to great things, gaining confidence and then taking up their duties. They may suffer losses but, thanks to divine or unexpected help, they recover.“

Jupiter and Mars in conjunction: „Honour comes only through hard work“

Jupiter and Moon in conjunction: „Prestigious offices, discovery of treasures“.

Sun and Mercury in conjunction: „Flexibility, common sense, distinction in careers in public life, love of beauty, charity, initiation into divine teachings, perseverance in the face of adversity“

Saturn and Mercury in square aspect

The square aspect connects zodiac signs separated by three signs (90 degrees). It generally leads to unfavourable predictions in Greco-Roman astrology, in this case: „he will be burdened with administrative duties and attacks from envious people.“

Ascendant in Capricorn

„Attachment to friends, prudence, good luck, ample resources, knowledge of the mysteries of sacred rites and foreign ways of life.“

The 12 places

The zodiacal sign of the ascendant was designated as the 1st place, in this case Capricorn. From there, the other 11 places were counted. Linked to this was a doctrine with its own prediction rules.

Moon, Mars, Jupiter in the 1st place: „a very fortunate career, well-deserved advances ahead of siblings, fame, virtue, and good humour. Advancement through brilliant campaigns, generosity, acquisition of great property, which later passes into the treasury.“

Mercury in the 12th place: „Intelligence“.

Saturn in the 9th place: „famous magicians, soothsayers, astrologers, famous philosophers who often let their hair grow long, interpreters of dreams.“

Before the zodiac: the Pleiades in Mesopotamian divination and their legacy in zodiacal literature

24.04.2023 by Maria Teresa Renzi-Sepe

Preliminary note: The following blog article is based on my PhD project, “The Perception of the Pleiades in Mesopotamian Culture”, funded by the Gerda Henkel Foundation and carried out at the Altorientalisches Institut of Leipzig. I have omitted half brackets to ease the reading in transliterations and translations of cuneiform texts. For the complete text editions, see “Further readings” at the end of the article.

Studying how celestial bodies were conceptualized in Ancient Mesopotamia before the emergence of zodiacal literature can aid our understanding of the cross-cultural, global spread of the zodiac. This is especially true in the case of the stars said to be “in the path of the moon,” a list of seventeen constellations through which the moon passes during its monthly route across the sky, according to the cuneiform MUL.APIN, an astral compendium of the first millennium BC. Twelve out of these seventeen would appear as the Babylonian zodiac at the end of the fifth or beginning of the fourth century BC.

Among the stars “in the path of the moon” but not included in the Babylonian zodiac, the first in order are the Pleiades, a cluster of stars in the north-west of the constellation Taurus (see fig. 1 and 2), which take their modern name from the seven sisters, the daughters of Atlas, from Greek mythology. As the subject of my forthcoming book entitled “The Perception of the Pleiades in Mesopotamian Culture”, the case of the Pleiades was a way to explore, through an intertextual approach, the conceptualization of celestial bodies before its transmission in the cuneiform zodiacal literature.

Fig. 1: “Taurus and the Pleiades”, Stellarium Astronomy Interactive. ( Accessed 17.04.2023.
Fig. 2: “Taurus”, plate 17 in Urania’s Mirror (1825) by Sidney Hall, restored by Adam Cuerden.

In Mesopotamia, the Pleiades are called MUL.MUL (written  in Old Babylonian ductus and in Neo-Assyrian ductus), literally “(many) Stars“ in Sumerian. At least from the Old Babylonian period (ca. 2000–1500 BC) onwards, the Pleiades are called zappu, “Bristle”, in Akkadian, conceived as the mane of the sign Taurus, pictured in the sky as a bull (see fig. 3). The Akkadian word zappu was then associated with the logogram MUL.MUL, merging two traditions. Unlike their counterparts in Classical mythology, the Pleiades are associated with male entities, sometimes warlike gods, sometimes bringers of fate, but always within a heptad (written dIMIN.BI, literally “these/their divine Seven”).

The Pleiades play a significant role in cuneiform celestial omens, inferences based on analogical relationships. These omens are collected in the divinatory series Enūma Anu Enlil (EAE), literally “When Anu (and) Enlil”, a composition dated from the Old Babylonian period to the end of the first millennium BC. From celestial omens, it emerges that the Pleiades and their phenomena (i.e., conjunctions, luminosity, dates of rising and setting) were thought to influence the outcome of the harvest through positive or adverse events predicted according to several analogical principles –calendrical, symbolic, or graphic. In the three omens from the series EAE mentioned below, one can notice the main topics of the predictions associated with the Pleiades, i.e. pestilence, rain, floods, and devastation:

DIŠ MUL.MUL ina ŠÀ-šú GUBmeš ÚŠmeš GARmešma dIMIN.BI KUR GU7meš

If the Pleiades stand inside it (i.e., the moon), a pestilence will occur, and the divine Seven will devour the country. (Verderame 2002: 176–177 § 1–6)

MUL.MUL u mulMAR UR.BI GUBmeš ŠÈGmeš u ILLUmeš GUBmešnim-ma ŠE.GÙN.NU TUR ina EN.TE.NA ŠUB- [bu-lì]

(If) the Pleiades and the Wagon stand together, rains and floods will come (and) the crop will be diminished. In winter, (there will be) a pestilence among the [herd]. (Reiner & Pingree 1981: 48 VI 2a)


If the Pleiades reach the Kidney-star, Adad (i.e., the storm god) will bring devastation. (K 5713+ obv. 8’)

Fig. 3: Drawing of the obverse of VAT 7851. From left to right: the Pleiades as seven stars with the caption MUL.MUL, the so-called “man in the Moon”, and Taurus as a bull (broken at the bottom left) with its mane accentuated.

The astrological texts dating to the Late Babylonian (and partly already Neo-Babylonian) period (ca. 626–30 BC) presume a different predictive framework than the omens in divination. The former forecast events based on computed celestial phenomena, with the zodiac as a spatial framework. Within this context, the Pleiades appear as a pars pro toto of the sign Taurus (GU4.AN.NA, alû, “Bull of Heaven”), or as its name. Nonetheless, Late Babylonian scholars drew on older predictions and mixed them with computed data to foresee events. As a result, the principles of divination are still detectable in a few astrological texts, such as BM 47494, an astrological fragment from Babylon or Borsippa, written by the scribe Iprāya before 337 BC. Its content is focused on weather and market forecasts from the positions of planets within zodiacal constellations. As shown in the lines mentioned below (BM 47494 obv. 19, 28, 31), predictions like the ones in the Pleiades omens mentioned above were still considered but likely associated with Taurus:

ana ÚŠmeš ina ŠÀ MUL.MUL mulGU4.AN.NA u mu[lSI]PA.ZI.AN.NA

For the pestilence: inside the Stars, the Bull of Heaven and the [Tr]ue Shepherd of Anu (i.e., Taurus).

ana ŠÈG A.GU4 ina ŠÀ mulKU6 mulGU.LA u MUL.MUL

For the rain (and) flood: inside the Fish (i.e., Pisces), Gula (i.e., Aquarius) and the Stars (i.e., Taurus).

ana ZI me-ḫe[-e UD.D]È?.RA.RA ri-iḫ-ṣu ina ŠÀ MUL.MUL u mulLÚ.ḪUN.GA

For the rising of a violent stor[m?, devast]ation (and) destruction: inside the Stars (i.e., Taurus) and the Hired Man (i.e., Aries).

Judging from the sources above, it seems that the conceptualization of the Pleiades in omens survived into the zodiacal literature, although the Pleiades have been “absorbed” by Taurus, and forecasts have different assumptions and purposes from the omens. One wonders how far intertextual studies between zodiacal literature and celestial omens could lead us to a new understanding of how ancient thinkers processed divination via the zodiac to find solutions to their society’s needs. 

Bibliography and further reading:

Hunger, H. 2004. “Stars, Cities and Predictions” in Burnett, C., et al. (eds.) Studies in the History of the Exact Sciences in Honour of David Pingree. Leiden-Boston: Brill, pp. 16–32.

Hunger, H., Steele, J. 2019. The Babylonian Astronomical Compendium MUL.APIN. London-New York: Routledge.

Ossendrijver, M. 2021. “Weather Prediction in Babylon”. Journal of Ancient Near Eastern History 8/2, pp. 223–258.

Reiner, E., Pingree, D. 1981. Babylonian Planetary Omens, II. Bibliotheca Mesopotamica. 2/2, Malibu: Undena Publications.

Verderame, L. 2002. Le tavole I-VI della serie astrologica Enūma Anu Enlil. Nisaba 2. Roma: Di.Sc.A.M.

The new fragments from Hipparchus’ star catalog and the mathematization of the ancient astral sciences

09.02.2023 by Victor Gysembergh (Léon Robin Research Center on Ancient Thought, CNRS)

The discovery of fragments from Hipparchus’ star catalog sheds new light on a major development of positional astronomy. Hipparchus of Nicaea was a Greek astronomer active in the Eastern Mediterranean (likely in Rhodes and Nicaea) in the second century BCE. Based on ancient reports, he has long been thought to have composed the first catalog of stars to include precise numerical coordinates, representing a major step towards the mathematization of the ancient astral sciences as compared to previous qualitative descriptions of stellar positions.

In Volume 53, Issue 4 of the Journal for the History of Astronomy,Peter Williams of Tyndale House, Emanuel Zingg of Sorbonne Université and I have published new fragments of that catalogue from a palimpsest manuscript known as the Codex Climaci rescriptus. This was made possible by multispectral imaging of the palimpsest, performed by a team from the Early Manuscripts Electronic Library, the Lazarus Project of the University of Rochester, and the Rochester Institute of Technology.

These new fragments deal with the position of Corona Borealis. They provide coordinates for its extremal stars as well as figures for its North-South and East-West extension, all expressed in an equatorial system (with right ascension used for the East-West axis and codeclination for the North-South axis, where modern astronomers generally use declination). The discovery of the new fragments from Codex Climaci rescriptus further allowed us to confirm the hypothesis (formulated by, among others, Otto Neugebauer in his History of Ancient Mathematical Astronomy) that the star coordinates in an ancient Latin text known as the Aratus Latinus come from Hipparchus’ star catalog. The Aratus Latinus gives equatorial coordinates for the extremal stars of the Great Bear, the Little Bear and Draco, as well as figures for their North-South and East-West extension.

The use of an equatorial system by Hipparchus, as opposed to an ecliptical coordinate system, can be viewed as a logical choice for studying the positions of the fixed stars, because of its conformity with their diurnal motion. Furthermore, it had already been used by Hipparchus’ predecessors Aristyllus and Timocharis in the 3rd c. BCE. The use of this frame of reference presupposes the concept of celestial circles, which is absent from Babylonian astronomy but central to the development of Greek astronomy from Eudoxus of Cnidus onwards.

Instead, the Babylonian astronomers appear in their extant texts to have used a frame of reference based on the observed object’s angular distance from one of 28 fixed stars (the so-called “normal stars”). Interestingly, this angular distance appears to have been oriented roughly along the ecliptic (see Jones 2004), but it is not clear that the Babylonians used an orthogonal frame of reference based on the ecliptic (pace Graßhoff and Wenger 2017).

Centuries later, Claudius Ptolemy (ca. 100 CE – ca. 175 CE) famously used an ecliptical coordinate system, which accounts more easily for the shifting of coordinates over time due to the precession of the equinoxes. Nevertheless, the use of equatorial coordinates persisted into late Antiquity and the Middle Ages in the works of important authors such as Severus Sebokht, ʿAlī ibn ʿĪsā, al-Khwārizmī, Qusṭā ibn Lūqā and Raymond de Marseille[1].

The new evidence further allows us to assess the accuracy of Hipparchus’ star catalog. It appears to have been remarkably accurate, to within one degree of the real coordinates in Hipparchus’ time. Readers may easily simulate the real coordinates of stars for any given time by using Stellarium, a free and open-source computer planetarium developed by the Paris Observatory. Of course, the size of the dataset recovered to date from Hipparchus’ star catalog is limited, with coordinates for only 15 stars, and it may well be that other coordinates were less accurate. From ancient lists of the number of stars in Hipparchus’ star catalog, a total number of 692 or 693 stars can be reconstructed; the actual total may have been greater, but it was almost certainly smaller than the 1028 stars in Ptolemy’s star catalog.

The fragments from Hipparchus’ star catalog also provide valuable insights into the way Ptolemy composed his own star catalog, extant in Ptolemy’s Almagest. The evidence strongly suggests that Ptolemy borrowed some of Hipparchus’ observations for his own catalog, but also that he used independent data sources. These independent sources may have been other star catalogs and/or his own observations. We can only speculate as to how Ptolemy decided what source of data to use for each individual star.

Indeed, the fragments from Hipparchus’ star catalog renew a series of fascinating questions about ancient astronomy. For instance, how did Hipparchus work to produce an accurate list of hundreds of star coordinates? What instruments did he use? Did he work alone or with colleagues and/or dependents? Did he enjoy forms of institutional support or patronage? Did he use prior measurements inherited from predecessors in the Greek world and elsewhere? And what were his motivations in undertaking such work?

A study of the recycled manuscript of Aratos’ astronomical poem Phaenomenahas recently been published by Peter Williams et al. It is hoped that further imaging of the Codex Climaci rescriptus will reveal more fragments from Hipparchus. In turn, these may provide further clues on the development of positional astronomy in Antiquity and its role in the mathematization of the ancient astral sciences.

Codex Climaci rescriptus, f° 53v, beginning of the first column of erased text. Courtesy of Museum of the Bible Collection. © Museum of the Bible, 2021. Image shared under Creative Commons BY-SA 4.0 license, 2022. All conditions apply. Color image by Early Manuscripts Electronic Library, Lazarus Project of the University of Rochester and Rochester Institute of Technology.
Codex Climaci rescriptus, f° 53v, beginning of the first column of erased text. Courtesy of Museum of the Bible Collection. © Museum of the Bible, 2021. Image shared under Creative Commons BY-SA 4.0 license, 2022. All conditions apply. Multispectral image by Early Manuscripts Electronic Library, Lazarus Project of the University of Rochester and Rochester Institute of Technology, processing by Keith Knox.

Codex Climaci rescriptus, f° 53v, beginning of the first column of erased text. Courtesy of Museum of the Bible Collection. © Museum of the Bible, 2021. Image shared under Creative Commons BY-SA 4.0 license, 2022. All conditions apply. In yellow, tracings of the erased text by Emanuel Zingg (Sorbonne Université).
Codex Climaci rescriptus folio 48v, showing an illustration of Corona Borealis. Courtesy Museum of the Bible Collection. © Museum of the Bible, 2021. Image shared under Creative Commons BY-SA 4.0 license, 2022. All conditions apply. Spectral imaging by the Early Manuscripts Electronic Library and the Lazarus Project of the University of Rochester. Image processing by Vasilis Kasotakis.

[1] My thanks go to Flora Vafea (Al-Azhar University, Cairo, Egypt) for this list of authors.

Imagining the Sky: The Zodiac and Related Astral Imagery in the Ancient World

11. Novermber 2022, by Alessia Pilloni

program of the workshop.

Like all specific topics within the study of antiquity, astronomy too is polyhedral, and each of its expressions can be analyzed from different points of view. One might focus only on a particular textual genre, whether mathematical or literary, or on one particular artistic representation, but this does not always give a satisfactory sense of unity or a complete understanding of the subject. That is why bringing together experts in individual aspects, i.e., history of science, Egyptology, Assyriology, classical philology, papyrology, archaeology, and art history, is so crucial: the intersection of the different approaches sheds light on matters that would remain unsolved, but with wider perspectives, we pave the way for resolving old research questions and posing new ones.

The workshop “Imagining the Sky: The Zodiac and Related Astral Imagery in the Ancient World” aimed to be a bridge connecting the study of ancient astronomy in different times and places, and also between texts and visual representation. In particular, how the concept of the zodiac and related topics has been adapted in images of different times and places and for different purposes, which, from a cross-cultural point of view, has not been studied in depth so far. Both the materials available and the supports are varied: from the schematic and stylised drawings on clay tablets in Mesopotamia, to the rich and colorful representations in Egyptian temples, and further, from the Greco-Roman monuments and small objects bearing cosmic elements, to their adaptation in Indian and Japanese manuscripts.

This blog post is meant to be a tribute to the success of this meeting of researchers of ancient astral sciences and a summary of the main topics that were discussed. All the presentations were connected by a common thread that motivated scholars to discuss and fascinated students and scholars from other disciplines.

Modern science at the service of ancient astronomy

A picture of the dome of the „Planetarium am Insulaner“, Berlin

There is nothing better than a projection of the sky at the planetarium to visualize and imagine the sky as seen in antiquity. Indeed, Susanne Hoffmann’s presentation at the Planetarium am Insulaner opened the workshop. The purpose was to show how the heavens and their moving bodies looked 3000 years ago in Babylon, when expert observers divided the sky into twelve segments identified by twelve constellations, the zodiac.

It is a great advantage to use modern instruments in order to visualize the data from ancient texts and images. On a virtual sky one can project the data from texts and images at different times and places in ancient history: the Babylonian lists of stars and constellations in the MUL.APIN compendium, Ptolemy’s coordinates, the uranology of Hipparchus and Aratus, the Zodiac depicted on the Farnese globe and so forth.

Images of the ancient sky and the texts referring to them extend beyond Mesopotamia, Egypt, Greece and Rome. For this reason, a group of researchers at the Max-Planck-Institut is working on a database on the materiality of the heavens in different cultures. The zodiac, for example, is transmitted and represented with characters from the transmitting culture but also adapted to the culture of the receiver, and patterns of transmission and influence can be traced as far as India and the Far East (China and Japan), as shown in the presentation by Sonja Brentjes.

Mesopotamian diagrams and drawings

Speakers: Jeanette Fincke, Wayne Horowitz, Willis Monroe, Marvin Schreiber, John Steele, John Wee

While there is an abundance of cuneiform tablets providing evidence of astronomical scientific activity in Mesopotamia, only a few also bear traces of graphic representations. The contributions of Assyriologists have in fact focused on this: the interaction between what is written and what is drawn on the tablet, meaning drawings and diagrams. Some drawings carved on the tablets are clearly depictions of constellations, like the ones in the famous astrological tablet VAT 7847.Assumptions about the diagrams, however, such as the ones that appear on the Neo Assyrian circular tablet K 8538, which were interpreted as stylised constellations during the time of the pioneers of Assyriology, such as Archibald Henri Sayce and Ernst Weidner, are to be re-examined. There is still no firm understanding: it is not even certain that the representations refer to astral elements. What is truly important is to reconsider the sources and the previous interpretative positions, in light of the new sources, and adapt them to advances in modern knowledge of Mesopotamian culture. 

detail of the diagrams in the Neo-Assirian circular tablet BM 8538, British Museum, London.
detail of the Seleucid calendar text for the zodiacal sign Leo VAT 7847, Vorderasiatisches Museum, Berlin

Maps of the sky in ancient Egypt

Speakers: Victoria Altmann-Wendling, John Baines, Yossra Ibrahim, Christian Leitz, Daniela Mendel-Leitz, Rune Nyord.

The first example that springs to mind is certainly the spectacular representation of the zodiac in the ceiling of the temple of Hathor in Dendera. There are certainly others: representations of the sky are very well attested in sarcophagi, pyramid ceilings and temples. The central theme is the presence of the personifications of the cosmic elements, such as planets and constellations, for example, the decans, the hours of the day, the winds, and so forth. Such representations aim to be sorts of “maps” of the heavens and are populated by deities and creatures. For instance, a pig swallowing celestial bodies might represent eclipses, and certain animals (scarab and falcon) are often shown carrying the sunthe actions that they perform represent the myth behind the astronomical event.

These images contain elements that confirm stylistic and cultural influences from outside Egypt, but also strong Egyptian features. Once again, the perfect example is the zodiac: a concept originating from Babylonia, but whose elements are represented with the Egyptian iconographic repertoire.

detail of the Hathor temple in Dendera, Egypt.

Images of the cosmos in Greco-Roman art and beyond

Speakers: Benjamin Anderson, Nicola Barbagli, Ilaria Bultrighini, Fabio Guidetti, Wolfgang Hübner, Stamatina Mastorakou, Fabio Spadini

In Greco-Roman art, representations of cosmic elements are found on coins, on monuments, mosaics, gems, and other objects. Much has already been said about such artifacts from an artistic point of view, but during the workshop the focus was on the interpretation and meaning of the schemes in which the astral elements are arranged.

From the point of view of written sources, Hellenistic astrology presents a highly sophisticated way of reading the signs, based on geometrical schemes.

On the other hand, in certain artifacts the disposition of the zodiac can assume different dispositions, with the signs oriented differently, for decorative reasons. This brings certain artistic objects far from an astrological purpose.

Upper left: Reverse of a medallion of Antoninus Pius (RPC IV.1 5867), minted in Nicaea, Bithynia, Turkey.
Bottom left: Pavement mosaic, Landesmuseum, Bonn.
Right: Farnese Globe, Museo Archeologico Nazionale, Naples.

Some concluding thoughts

The attendance was plentiful both online, with more than a hundred virtual participants, and in person, with sixty participants in the conference room, some of them from overseas institutions: an excellent example of the resumption of in-person research activities, after two arduous years of pandemic.

For a glimpse into the future: the papers will be part of the proceedings volume, which will be curated by Mathieu Ossendrijver and Andreas Winkler and available in open access by winter 2023.

To conclude with a thought of gratitude, all that has been presented and discussed was enriched by a pleasant atmosphere of unity, sharing, and openness to dialogue on the part of the participants, perceptible not only during the presentations, but also during breaks and convivial moments.

It has been an intense dive into the world of ancient astronomy: “imagining the sky”, through pictures and texts, how the ancient people saw and perceived the heavens above their heads, tried to glean signs, and unlock its secrets by creating methods to calculate its motion in order to predict the future.

The Zodiac Glossary

22. August 2022, by Christian Casey

The Zodiac Glossary website is now available online at

A Glossary of Zodiacal Terms

As one component of the broader aims of the Zodiac Project, we’re creating a glossary of zodiacal terms from the ancient Mediterranean and near East.

The usefulness of such a project for our research is easy enough to see from a few examples. Say that you wanted to know about the Egyptian conceptualization of Aries. You could look up the English word in the glossary (“Aries”), find a few matching examples, and see that this concept is realized in Egyptian as: 𓇋𓋴𓏪𓄛𓏤 ỉsw “ram” and: 𓁶𓏤 dpỉ “first” (as in the example from Andreas Winkler’s recent blog post “A New Look at an Old Horoscope”). 𓇋𓋴𓏪𓄛𓏤 ỉsw “ram” is easy enough to understand, but what about 𓁶𓏤 dpỉ “first”? One likely explanation is that the Egyptian zodiac was ordered like the Babylonian one, with Aries as the first element and the others following after. This sort of observation immediately suggests a cultural connection between the two, which is exactly what we are here to explore.

Or you might wonder about the connections between the gods and the planets. For instance, the god Jupiter is associated with Greek Zeus and Egyptian Amun, but the planet Jupiter is known by a variety of Egyptian names: “Horus the merchant”, “Horus the secret one”, “Horus the magician”, none of which have anything to do with Jupiter or Zeus or even Amun. Looking at such evidence, it is reasonable to hypothesize that the Egyptian planet names predate any direct connection with neighboring cultures and were borrowed into the zodiacal system from local traditions. Here we have the opposite of the previous example: a telling lack of similarity where we might expect to find one. This sort of detail helps nuance our understanding of the spread of the zodiac between various cultural groups.

Even with such simple examples (where the explanations are already known in advance), it’s clear enough that having such a glossary simplifies the task of doing research. Looking at texts one at a time demands a strong memory for seemingly minor details, such as the spelling of a single word, while extracting these details and putting them together into one view makes the connections much more obvious. It also allows us to detect relationships between ancient languages, even in cases where no single member of the team knows all the languages involved.

All Beginnings are Difficult

We can talk endlessly about constructing such a glossary, but until we actually start doing it there’s no way to know how it’s actually going to work. At some point, we have to stop talking and start building, then adjust our strategy as we go along. That’s why we now have a prototype version, currently in alpha testing.

[The Zodiac Glossary working prototype as of July 20, 2022.]

The final version will probably be different in many ways, but you can already see most of the parts that we wanted to include from the beginning.

On the left, there’s a way to search for existing lemmas, a way to filter by languages, a way to sort the results, and an option to add a new lemma (only available to registered users in the final version).

On the right side, in the Lemma panel, there’s the usual information you would expect in any ancient language glossary, plus lists of variants and quotations to help us with our research. Finding an interesting pattern or cross-cultural connection is not the end of the story. We also have to refer back to the original text to dig in further. Or, at the very least, we need to cite our sources. Finally, there is a way to delete the lemma, which will also only be available to registered users in the future.

One important feature, which is not pictured here because I haven’t implemented it yet, is a way to link different lemmas together. For instance, it would be useful to link the Greek lemma κριός krios with the Egyptian 𓇋𓋴𓏪𓄛𓏤 ỉsw because both refer to the sign Aries. Having those links between ancient languages will allow us to explore connections in a lateral traversal through the networks of relationships within languages. This is one of the most important aspects of collaborative work like this involving specialists in different fields: we can find things that no single one of us is equipped to discover alone.

The Glossary will also be available to anyone who wants to use it via this same public-facing website. However, editing features will only be available to registered users. The long-term destiny of this part of the project is still an open question. Perhaps others will take it over and build on it after us (in which case we will allow other collaborators to register as editors) or perhaps it will simply remain online as a valuable tool for anyone who wants to use it. The one outcome that we are designing against from the beginning is one that is all too familiar with grant-funded academic projects: disappearing into the ether.

Surviving the Academic Grant Cycle

Zodiac is funded by a five-year ERC grant. Like all such projects, its trajectory is predicated on the assumption that deliverables come in the form of traditional academic publications: books, journal articles, etc. But books are very different from databases. For one thing, the cost of producing and preserving a physical book is paid by the reader (in one way or another), while the cost of serving up a website is paid by the creator. At the same time, books can remain on library shelves indefinitely. By the time a library book decays from age, the information in it will have been replicated elsewhere or superseded entirely. But websites don’t simply sit on shelves. They must be maintained and paid for on a continuous basis.

The success of this project in the long term requires a solution to this problem: a website that remains functional at very low cost forever. There are already ways of creating free websites with static content (content that is prepared in advance and doesn’t change), but there is no easy way to build a free website for dynamic content (content generated on the fly, such as a webpage that includes information pulled from a database). The Zodiac Glossary is thoroughly dynamic, so we need to find an affordable way to build the site that allows it to become free (or very nearly free) after the term of the grant ends.

Our current working approach is to use a variety of tools on the Amazon Web Services platform in an arrangement that keeps costs as low as possible. There is an inevitable tradeoff here. While it may be possible to keep costs down using AWS “Free Tier” services, this limits the number of visitors that the website can serve. Such an approach may prove ideal for smaller academic projects, where daily visitor numbers are expected to remain low, but it may not work in all circumstances.

Depending on the nature and scope of a project, different solutions may be creatively combined to maximize benefit and minimize cost. I’m currently working on several simultaneous approaches to the academic website funding problem (some developed as part of my work with Zodiac, some from my previous position as the CLIR postdoc at ISAW). If you’re interested in learning what I’ve discovered or discussing other solutions, consider attending my paper at this year’s ASOR conference in Boston (November 16–19), “Star Seeds: Building a digital glossary for the Zodiac Project that will outlive the project’s funding” in the Digital Archaeology and History section.

Coming soon…

Though the Zodiac Glossary is still in development, we expect to have a working, publicly-available version of the website online within the next few months. Check back for more updates, and feel free to contact me with questions or ideas:

Als die Babylonier das Horoskop erfanden

Tagesspiegelbeilage vom 02.07.2022

Das Institut für Wissensgeschichte des Altertums wird neue Aspekte des menschlichen Wissens in der Antike ausleuchten: Das Projekt „Zodiac“ erforscht die Erfindung des Tierkreises durch die Babylonier

Das Original hängt im Louvre. Antiker Tierkreis aus der Stadt Dendera in Ägypten (1. Jahrhundert v. Chr.). Bildquelle: Wikicommons

Ist es irreführend zu fragen, ob die Einweihung eines neuen Instituts an der Freien Universität unter einem glücklichen Stern stand? Am 17. Juni 2022 geboren, hat das Institut für Wissensgeschichte des Altertums das Sternzeichen Zwilling mit Aszendent Jungfrau. Dass zum Zeitpunkt seiner Eröffnung, um 11 Uhr, die Sonne im 9. Haus und der Merkur im 8. Haus stand, deutet darauf hin, dass das Institut besonders neugierig und darauf ausgerichtet sein könnte, seine Mitmenschen zu verstehen. Jupiter im 6. Haus spricht dafür, dass es hohe Standards im beruflichen Umgang mit anderen beachten und einfordern wird.

Wissenschaft oder Aberglaube?

Nun man kann derlei Vorhersagen und Horoskopie als Aberglauben abtun. Tatsächlich aber gehen all ihre Bestandteile – der Tierkreis (lat. zodiacus, von griechisch zodiakós), die Sternzeichen, die astronomische Berechnung der Planetenpositionen und die astrologische Interpretation des Ganzen – auf eine wissenschaftliche und kulturelle Revolution zurück, die in genau diesem Institut für Wissensgeschichte des Altertums in Zukunft unter anderem erforscht und gedeutet werden soll.

Der Wissenschaftshistoriker Professor Mathieu Ossendrijver wird eben diesen „zodiacal turn“, der sich im antiken Babylonien vor 2500 Jahren, also um 500 vor Christus, vollzogen hat, als Leiter des im neuen Institut angesiedelten Forschungsprojekts „ZODIAC – Ancient Astral Science in Transformation“ während der kommenden fünf Jahre erforschen.

Matthieu Ossendrijver ist nicht nur Althistoriker und Assyriologe, sondern auch Astrophysiker. Das ist insofern von Vorteil, als das ZODIAC-Projekt sich mit der Geburt der babylonischen Astralwissenschaft, also der Horoskopie, beschäftigen will.

Matthieu Ossendrijver nennt mehrere Elemente, die zusammenkommen mussten, damit die Babylonier die Sternzeichen und das Horoskop erfinden konnten: Erstens hatten sie schon über lange Zeit die Bewegungen der Himmelskörper, der Sterne und Planeten, beobachtet, aufgezeichnet und darin Regelmäßigkeiten und Muster erkannt. Zweitens entwickelten die Babylonier über die bloße empirische Beobachtung hinaus mathematische Techniken und Werkzeuge, mit deren Hilfe sie die Bahnen der Planeten und Sterne mathematisch berechnen und vorhersagen konnten. Ossendrijver nennt das den „mathematical turn“, der Teil des „zodiacal turn“ gewesen sei.

Erst dann wird verständlich, welche Bedeutung die Erfindung des Tierkreises vor 2500 Jahren hatte: Die Babylonier teilten nun den Himmel in zwölf Bereiche auf, denen jeweils eine Figur, ein Name und eine bestimmte Bedeutung zugeordnet wurde: den Tierkreis mit seinen zwölf Sternzeichen wie Widder, Zwilling, Jungfrau oder Löwe.

Althistoriker, Assyriologe, Astrophysiker. Mathieu Ossendrijver leitet ein Forschungsprojekt im neu gegründeten Institut für die Wissensgeschichte des Altertums.
Bildquelle: Lorenz Brandtner

Schließlich verbanden die babylonischen Astralwissenschaftler diese zu einem Wissenskorpus, aufgrund dessen Berechnungen, zu welchem Zeitpunkt welche Planeten wo im Tierkreis standen, Bedeutungen und Bedeutungszusammenhänge formuliert werden konnten.

Doch was ist eigentlich der Tierkreis, den die Babylonier erfanden und der bis heute in Zeitschriften als Grundlage für Horoskope dient? „Eigentlich handelt es sich dabei um ein Band, einen Himmelsstreifen, der den Bereich ein paar Grad unter und ein paar Grad über der scheinbaren Sonnenbahn und den scheinbaren Mond und Planetenbahnen umfasst“, sagt Matthieu Ossendrijver. „Mit dem freien Auge ist der Tierkreis nicht zu sehen: Vielmehr erfanden die Babylonier eine mathematische Konstruktion, die sie nun in zwölf Teile zu jeweils 30 Grad einteilten, und bei der sie jeden Abschnitt nach dem in ihm markanten Sternbild benannten.“

Erst durch diese Art der berechnenden Astrologie, die etwa die Sonne im 8. und den Saturn im 5. Haus verortet, kann darüber gerätselt werden, was das für ein Kind – oder ein Institut – bedeutet, das an diesem Tag das Licht der Welt erblickt.

Wie hielt sich die Deutung alter babylonischer Zeichen bis heute?

„Für die Babylonier waren die Sterne und die Himmelsphänomene göttliche Zeichen an die Menschen“, erläutert Mathieu Ossendrijver. Die Stellung der Planeten bei der Geburt eines Kindes verrät also etwas über dieses Kind. Und die Astrologie dient dazu, diese göttliche Botschaft zu entziffern und zu verstehen.

Warum aber war – und ist – die Horoskopie dermaßen erfolgreich? Wie konnte sich die babylonische Astralwissenschaft zuerst über die antike Welt ins Römische Reich, dann ins Judentum, in den Islam und ins Christentum hinein weiterverbreiten? Und sich so hartnäckig halten, dass heute noch Menschen zu Jahresbeginn ihr Horoskop studieren, um zu erfahren, ob zum Beispiel das Glück in der Liebe winkt oder ein Rückschlag im Beruf droht?

Für deren Attraktivität spricht dem Wissenschaftler zufolge, dass die Horoskopie einerseits das menschliche Bedürfnis anspricht, etwas über die eigene Zukunft zu erfahren.

Andererseits überzeugt das abstrakte System aus Zahlen und Sternbildern: Es lässt sich unabhängig von einer bestimmten Sprache, Geschichte oder Schrift sehr leicht übersetzen. Man stehe noch am Anfang, sagt Mathieu Ossendrijver, das Institut für Wissensgeschichte – unter der Leitung von J. Cale Johnson, Professor für Wissensgeschichte – ist schließlich gerade erst eröffnet worden. Aber man verrät wohl nicht zu viel, wenn man sagt: Die Antwort steht auch in den Sternen.

The origins of the planetary week

2 May 2022, by Ilaria Bultrighini

As part of my previous role as member of the ERC project Calendars in Antiquity and the Middle Ages: Standardisation and Fixation (University College London; PI: Prof Sacha Stern; 2013-2018), I investigated the origins and development of the seven-day week in the Roman Empire. Despite its interest and obvious relevance to the present, the early history of the seven-day week had not been systematically studied before. The only comprehensive study of the seven-day week in antiquity up to then was a book published by Colson in 1926. Yet, the wealth of epigraphic and documentary evidence that has subsequently been discovered made Colson’s work outdated. As part of my research, I searched for, collected, and analysed references to individual days of the week and to the seven-day week as a whole across the entire corpus of epigraphic, documentary, and literary sources in Greek and Latin from throughout the Roman Empire. This relatively large body of evidence covers the whole Roman Imperial period and Late Antiquity, until approximately the end of the sixth century CE. The main output of this research is a substantial book chapter I wrote jointly with Sacha Stern, which also includes an examination of the early history of the Jewish Sabbath week based on his detailed analysis of relevant Hebrew and Aramaic sources.

The week as known today is the result of the merging of two different cultural traditions: the Jewish, biblical week and the planetary week of astrological origin. Although the idea of dividing the days of the year into cycles of seven days and of naming each of these days reaches far back into biblical antiquity, the seven-day week as a structure of time reckoning was in fact devised in the early Roman Imperial period. In the course of the first two centuries CE the Jewish and astrological traditions gradually converged to create a single, standardised seven-day week. The Christianisation of the week in the fourth century led to its wide diffusion in the Roman Empire, but its mixed cultural origins—Judeo-Christian and astrological—persisted up to Late Antiquity and the early Middle Ages.

Silver statuette of the goddess Fortuna supporting a stand on which rest seven busts
representing the planetary deities of the week. From Mâcon, France, c. 150-250 CE
© The Trustees of the British Museum

In this blog post, I focus on one of these two traditions, the astrological one. The planetary week makes its first appearance in Italy in the second half of the first century BCE. At that time and throughout the first century CE the evidence for it remains limited to the city of Rome and other parts of central-southern Italy. It is only in the course of the second century CE that the planetary week is attested outside of the Italian peninsula, including in the eastern Mediterranean. Still, the evidence suggests that even when the planetary week did reach the East, it remained a considerably more limited phenomenon compared to the western part of the Roman Empire. On this basis, Sacha Stern and I assume that the planetary week is a ‚Roman‘ product. This conclusion differs drastically from earlier scholarship, in which the general consensus is that the planetary week originated from Babylonian, Egyptian, or Hellenistic astrology. Colson did not attempt to pinpoint any specific tradition for its invention, but still presumed a ‘spread from east to west’. Nevertheless, there is in fact no evidence of a planetary week in Egypt, Mesopotamia, the Hellenistic world, or anywhere further east, before the second century CE. The evidence suggests, therefore, that the tradition could only have originated in Italy.

The sequence of the planets within the week is as follows: day of Kronos/Saturn (Saturday), day of Helios/Sol (Sunday), day of Selene/Luna (Monday), day of Ares/Mars (Tuesday), day of Hermes/Mercury (Wednesday), day of Zeus/Jupiter (Thursday), and day of Aphrodite/Venus (Friday). This differs from the order of the planets in the Hellenistic astronomical and cosmological traditions, in which the planets were arranged according to their distance from the earth and/or the length of their revolution, originally as Saturn, Jupiter, Mars, Mercury, Venus, Sun, Moon, and in later, Roman sources as Saturn, Jupiter, Mars, Sun, Venus, Mercury, Moon—the so-called Chaldean order.

Copper-alloy nutcracker-shaped object. On the two shanks are busts of the planetary week deities. From Roman London, 2nd – 4th century CE
© The Trustees of the British Museum

The earliest mention of the generally accepted explanation for the order of the planets within the week in the literary sources is by the Alexandrian astrologer Vettius Valens (mid-2nd century CE), followed a half-century later by the historian Cassius Dio. The theory is based on the role of the seven planets as rulers of hours. The week was mapped out in 168 hours; the seven planets (in the so-called Chaldean order) were assigned serially to the 24 hours of the day, and then to the 168 hours of the week, the planet assigned to the first hour of each day becoming the ruler of that particular day. Therefore each planet was assigned both to specific hours of the day and to a whole day. The resulting sequence runs from the day of Saturn (Saturday) to the day of Venus (Friday). It is thus clear that the planetary week was not founded on any astronomical principle or system; the correspondence of days of the week with the seven celestial bodies is indeed abstract, artificial.

In fact, this concept is attested at least a half-century before Vettius Valens in a fragmentary inscription from the area of Potenza Picena (ancient Potentia) in central Italy, near the Adriatic coast. The inscription has been dated mainly on the basis of letterforms to around 100 CE or possibly earlier, even as early as the Augustan period (27 BCE – 14 CE). The fragment preserves part of a repeating list of planets in the cosmological sequence; each planet is given a number and a letter (B, N, or C) designating it as good (bona), harmful (noxia), or indifferent (communis). In other words, this inscription presents the sequence of planetary hours as described by Vettius Valens and thus suggests that such a scheme was most likely of Italian origin. This would tie in well with the Italian origins of the planetary week Sacha Stern and I are arguing for.

Further reading:

Bultrighini, I. and Stern, S. (2021) „The seven-day week in the Roman Empire: origins, standardization, and diffusion“. In S. Stern (ed.), Calendars in the Making: The Origins of Calendars from the Roman Empire to the Later Middle Ages (Time, Astronomy, and Calendars: Texts and Studies, 10). Leiden: Brill, 10–79.

Colson, F.H. (1926) The Week: An Essay on the Origin and Development of the Seven-Day Cycle. Cambridge: Cambridge University Press.