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Stargazing in Mesopotamia: Astronomy and Astrology

In ancient Mesopotamia, the skies held more than just twinkling stars. Ancient civilisations meticulously observed celestial bodies, connecting astronomy and astrology in a complex system of knowledge. This article explores how these practices differed from modern astrology, focusing on their role in understanding the divine, predicting events, and shaping societal structures. Through an examination of a Neo-Assyrian letter and a Hellenistic horoscope, this article will behold the sophistication of astronomical observations and their profound influence on both spiritual comprehension and the advancement of early science.

Astronomy and Astrology: An Overview

The observation of celestial bodies and the systematic collection of data about their movements and effects on planet Earth played a significant role in ancient Mesopotamia. Priests in Babylon and other cities used (ziggurats, tall, tiered) ziggurats: tall and tiered structures (deleted comma) to study the night sky, initially focusing on predicting weather patterns based on planetary movements. They observed the planets' motion compared to fixed stars and linked them to deities, believing the gods controlled weather and other earthly events, like diseases, floods, and animal behaviour. This focus on celestial bodies marked the beginnings of astrology, initially used for state affairs only, as it will be discussed later (Jerome, 1973, p. 122-123).

Greek and Roman astrology were influenced by Mesopotamian and Egyptian practices. However, with the beginning of the first millennium BCE, Christianity's rise weakened astrology due to its polytheistic nature. Consequently, the centre of astrological studies shifted to the Near East, initially Persia and later the Arab world. Arab astrologers focused only on the "wandering planets" (unlike Greeks, who included fixed stars) and simplified horoscope creation, making astrology accessible to everyone. By the 16th century, astrology became ingrained in Renaissance cosmology, influencing everything from daily life to national affairs: specialists offered numerous services, from weather forecasts to personal horoscopes based on birth times (nativity) and question-specific charts (horary questions). However, advancements in astronomy like the telescope and discoveries by Copernicus, Kepler, and Newton weakened astrology's foundations. With a new understanding of the universe and planetary movement based on physics, astrology lost favour and became viewed as an outdated superstition (Jerome, 1973, p. 124-125).

A portrait of a man, an astronomer, with long hair dated 1580.
Figure 1. Nicolaus Copernicus (Anonymus, ca. 1580).

The marginalization of astrology can be understood as part of a broader trend in the 17th and 18th centuries. Many practices, like alchemy and magic, were dismissed as superstition during this period (Vermij and Hirai, 2017, p. 407). However, astrology experienced a resurgence in the 1930s and continues to hold a prominent place in popular culture. Today, most people are familiar with their sun sign, and many believe in the influence of celestial bodies on their lives (Thagard, 1978, p. 224).

Nowadays, the observation of celestial bodies can be divided into two main branches: astronomy and astrology. Astronomy observes the sky to find empirical data and explain phenomena using parameters that can be measured with tools; from the collection and examination of data, researchers can formulate theories about the functioning of the universe. Differently, astrology can be explained as the observation of the same empirical phenomena, but with the addition of the interpretation of such phenomena as influencing the life of living beings through magical—therefore, not measurable—schemes. In antiquity, the determination of destiny on nativity was only a part of astrology, as there were other applications of this type of knowledge, like astrological medicine (Thorndike, 1955, p. 273). Moreover, the distinction between astronomy and astrology was not active during the Middle Ages, when the calculation of various astrological data (like horoscopes, the character of the planets, etc.) was part of the astronomia curriculum (Vermij and Hirai, 2017, p. 405).

A parchment paper page from an ancient manuscript with a circle representing the solar system and the planets.
Figure 2. Illustration from a manuscript of the work Aratea, ca 830-840.

While both astronomy and astrology fix their gaze on the heavens, their interpretations diverge greatly. Astronomy meticulously observes and records celestial objects and events, building robust models and theories based on verifiable evidence. Astronomical theories gain strength when they can predict specific observations, which are then rigorously assessed through experimentation or real-world data collection. This rigorous testing process allows astronomers to refine their understanding of the universe. In contrast, astrology interprets celestial movements and positions as influencing human lives and earthly events. Astrological theories are not based on the scientific method and cannot be reliably evaluated through experimentation. They often rely on unfalsifiable assumptions and symbolic explanations that cannot be objectively measured (Thagard, 1978, p. 225).

A photograph of a space telescope above planet Earth.
Figure 3. The Hubble Space Telescope above Earth (NASA).

The Role of Astronomical Observations in Ancient Mesopotamia

The observation of celestial movements played a fundamental role in Ancient Mesopotamia, where astronomical observations were employed to understand the correlations between celestial movements and the things happening on Earth.

Among the most influential scholars on Mesopotamian astronomy and mathematics was Otto Neugebauer, who paved the way—together with other researchers—to the understanding of Babylonian astronomical observations and calculation systems (Høyrup, 2017). On the more historical and philological side, Abraham Sachs and Hermann Hunger were among the most influential scholars because of the publication of the so-called ADART volumes, "Astronomical Diaries and Related Texts," which have been edited over the past 40 years and include the texts of hundreds of tablets of astronomical observations during the first millennium BCE (ADART 1989-2020). More tablets dated to the second millennium BCE also offer valuable information about systematic astronomical observation (Sachs, 1974, p. 43).

A clay tablet with cuneiform inscriptions describing the passage of the Halley comet.
Figure 4. Astronomical Diary tablet mentioning the comet of Halley (

An important fact to keep in mind when approaching astronomical observations and their astrological applications in ancient Mesopotamia is that the scope of observationthat is, the interpretation of affairs happening on Earth and their correlation with celestial movementsdoes not imply that the degree of precision in observing the sky was insignificant. Conversely, we can say that in the late first millennium BC, after the conquest of Alexander the Great,

[...], Babylonian astronomy was a fully mathematical science of great elegance and subtlety and, occasionally, of noteworthy accuracy. As such, it embodies not only the first quantitative approach to physical phenomena, but also the first formation of general theoretical models within which particular physical phenomena were handled (Rochberg-Halton, 1991, 107).

While the Babylonian astronomers could not use modern tools and calculators, they were able to observe the sky with remarkable precision. They collected data and their interpretations into many works, the main being the clay tablet series called Enuma Anu Enlil, which translates as "when in the sky, Anu," and describes how the celestial phenomena, guided by the sky god Anu, were correlated to things happening on Earth.

A marble bust of the King of Macedon during the 2nd century BCE as a young man.
Figure 5. Alexander III the Great (Lysippus, 2nd century BCE).

Divine Determinism?

Among the main concepts commonly attached to Mesopotamian (Babylonian) astrology is "divine determinism," that is, the belief that everything in the human world was pre-determined by the gods and was inscribed in the stars. This might result from a superficial reading of the astronomical tablets, which are generally constructed as follows: to a specific observed phenomenon follows an interpretation, creating what is called an "omen" (a Latin word meaning "destiny"). However, Mesopotamian astrology cannot be reduced to a mechanical system (Parpola, 1993, 48). On the contrary, the affairs happening to human beings were not inescapable, but it was the precise duty of astrologers to collect data and formulate omens to ensure the kings would make the right decisions in demanding situations. In the Mesopotamian concept of kingship, the king "was a link between god and man, a sort of god on earth, and as such, subject to demands of perfection not imposed on any other individual in the society" (Parpola, 1993, p. 52).

The main duty of the king was, therefore, to maintain the balance between the godly and human worlds and the sky and its phenomena were the ways the gods communicated with the king, and the omens could be both positive and negative. To understand how to conduct the state, the king had to seek the help of astrologers, who were trained in celestial knowledge and could understand how to help the king (Parpola, 1993, p. 53).

The cover of a modern book about the astrological reports to Assyrian kings.
Figure 6. The volume 8 of State Archives of Assyria. (University of Pennsylvania).

Making the Right Decisions in the Neo-Assyrian Empire

To understand the role of astronomical observation and the astrological approach in Ancient Mesopotamia, two texts from the first millennium BCE can be useful: the first is a letter to the Neo-Assyrian king Esarhaddonwho reigned in the period from 681 to 669 BCEby one of his astrologers, Balasî; the second text is a personal horoscope from the Hellenistic period. The letters from astrologers to the kings of the Neo-Assyrian Empire (10th - 7th century BCE) are an invaluable source to understand the role of astrology within the process of decision-making and to observe the profound traditional social role it had. These texts can be found mainly in volume 10 of the publication SAA, "State Archives of Assyria." The following extract is part of letter 59:

To the king, my lord: your servant Balasî. Good health to the king, my lord! May Nabû and Marduk bless the king, my lord! Concerning the crown prince about whom the king, my lord, wrote to me: "I have been told that he should not go outdoors on the 1st day" — this applies rather to the 2nd day. Concerning the 1st and the 4th days about which the king, my lord, wrote to me: "Which one is favourable?" — both are favourable. We call the 4th day a 'new day.' A new day has the same qualities as the beginning of a month; it is favourable. As to what was said to the king: "On the 1st day he may not go outdoors," does the crown prince now go out of the outer gate? Said the king: "The crown prince should enter into my presence." What has entering to do with going out? Concerning Aššur-mukin-paleya about whom the king, my lord, spoke — the 4th day is good, let him come. The planet Mercury signifies the crown prince, and it is bright, clothed with brilliance. So in view of what should he not come? The moon completed the day in this month (Parpola, 1993, n. 59).

The letter reveals a fascinating detail about a royal visit – the king consulted an astrologer to determine the most auspicious timing for the crown prince's arrival, the future king Ashurbanipal. While this practice might seem unusual today, it underscores the fundamental importance placed on the safety and well-being of the royal family. By seeking celestial guidance, the king aimed to ensure a smooth and uneventful visit, minimizing any potential risks to himself and his heir. This episode highlights the crucial role astrologers played in the royal court, their pronouncements influencing even seemingly mundane aspects of royal life.

A stele of brown color with the basrelief of an Assyrian king, Esarhaddon, and some cuneiform characters.
Figure 7. King Esarhaddon (7th century BCE).

Personal Astrology: a Hellenistic Horoscope

The collapse of the Neo-Babylonian kingdom under Persian rule marked a turning point for local empires in Mesopotamia. This shift appears to have impacted the perceived importance of astronomy, as evidenced by the lack of surviving astrological letters addressed to the king. However, astronomical tablets recording celestial observations and omens continued to be produced and, interestingly, the Hellenistic period following Alexander the Great's conquest in 330 BCE saw a surge in astronomical diaries, with hundreds of tablets documented – a stark contrast to the apparent decline in astrological communication with the king. The Persian conquest, therefore, resulted in a change in the role of astrology for Mesopotamian rulers. Unlike their predecessors who heavily relied on celestial omens, the Persians, with their distinct cultural background, placed less emphasis on astrological observations in decision-making. This shift in priorities likely fuelled a growing interest in personal astrology, as evidenced by the increase in documented horoscopes; however, this did not cause the abandonment of the astronomical observations for omen purposes to be substituted by horoscopes (Rochberg, 2020, p. 472).

Unlike modern horoscopes based on sun signs, a Babylonian horoscope would be intricately crafted based on the exact date, time, and location of a person's birth. The following example, dated 287 BCE, illustrates how a Hellenistic Babylonian horoscope was structured:

Year 24 (of the Seleukid Era = 287 BCE), Seleucus and Antiochus were the kings. Month Abu (July-August) 1, moonset after sunrise on the 14th, night of the 19(?). That day, the moon was to the west of "The southern ... of the Chariot, (by) 2 cubits. Last lunar visibility before sunrise was on the 27th. At that time, Jupiter and Venus were in Cancer, on the 10th Saturn's last appearance in Virgo, on the 14th Mercury's last appearance in the west in Virgo, Mrs in Leo, sun in Virgo. Ululu (August-September) the 16th was the (autumnal) equinox. Arahsamna (October-November), night of the 13th, a lunar eclipse occurred. Totality occurred in Taurus. The son of Tar-sa-mu-ku-us was born" (Rochberg, 1998, 61-63).

The sequence of information is composed by the name of the month and the time of the birth, followed by the recording of the sun, the moon, and the five classical planets: Mercury, Mars, Venus, Saturn, and Jupiter. The horoscopes record a very important fact: the precision of the observations and calculations of the Babylonian astronomers was high, and the interest in celestial movements kept being a distinctive characteristic of the scientific production of the Babylonian culture even in the centuries under the Macedonian and Parthian rule at the end of the first millennium BC (Rochberg, 1998, p. 4-8).

The two faces of a clay tablet with cuneiform signs about a horoscope.
Figure 8. A Hellenistic horoscope (LBAT 1462).

Beyond Stars and Suppositions: a Lasting Impact

While the observations of ancient civilizations like the Babylonians may not align with modern scientific understanding, they hold immense value in understanding the historical trajectory of technology, science, and societal development. These observations, though not employed for the same purposes as today, served as a crucial lens through which they interpreted the world around them. Examining these observations provides a window into the intellectual frameworks and beliefs that shaped ancient civilizations, offering insights into their worldview and the motivations driving their scientific pursuits. By tracing the evolution of technology and the accompanying observational practices, we can gain a deeper understanding of how these technologies were employed, their patterns of change, and the underlying motivations driving their development. This exploration unveils the intricate interplay between societal factors and technological advancements, shedding light on how a civilization like the Babylonians was shaped by both its technological prowess and the social context in which it operated.


From their temples, Mesopotamian priests meticulously mapped the heavens, developing both astronomy and astrology. While astronomy tracked celestial movements for weather prediction and later, cosmic understanding, astrology saw these movements as omens for earthly events and for millennia Mesopotamian kings heavily relied on this practice. Alexander's arrival shifted the focus and as astronomical observations continued, their role in royal decision-making declined. This coincided with a rise in personal horoscopes, meticulously crafted based on individual birth details. Though not aligned with modern science, ancient observations like those by the Babylonians offer a window into their worldview and scientific development. Studying these practices reveals the connections between their technology and society, shaping our understanding of their motivations and advancements.

Bibliographic References

Høyrup, J. (2017). Otto Neugebauer and the Exploration of Ancient Near Eastern Mathematics. Max Planck Institute for the History of Science, Preprint 488.

Jerome, L. E. (1973). Astrology and Modern Science: A Critical Analysis. Leonardo, 6(2), 121–130.

Parpola, S. (1993). Letters from Assyrian and Babylonian Scholars (State Archives of Assyria, 10). Helsinki.

Rochberg, F. (1998). Babylonian Horoscopes. Transactions of the American Philosophical Society, 88(1), i–164.

Rochberg, F. (2020). Hellenistic Babylonian Astral Divination and Nativities. In Hellenistic Astronomy. Leiden, Brill.

Rochberg-Halton, F. (1991). Between Observation and Theory in Babylonian Astronomical Texts. Journal of Near Eastern Studies, 50(2), 107–120.

Sachs, A. (1974). Babylonian Observational Astronomy. Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences, 276(1257), 43–50.

Sachs, A., & Hunger, H. (1988). Astronomical Diaries and Related Texts from Babylonia. Volume I: 652-262 BC (ADART I). Vienna: Verlag der Österreichischen Akademie der Wissenschaften.

Sachs, A., & Hunger, H. (1989). Astronomical Diaries and Related Texts from Babylonia. Volume II: 261-165 BC (ADART II). Vienna: Verlag der Österreichischen Akademie der Wissenschaften.

Sachs, A., & Hunger, H. (1996). Astronomical Diaries and Related Texts from Babylonia. Volume III 164-61 BC (ADART III). Vienna: Verlag der Österreichischen Akademie der Wissenschaften.

Thagard, P. R. (1978). Why Astrology is a Pseudoscience. PSA: Proceedings of the Biennial Meeting of the Philosophy of Science Association, 1978, 223–234.

Thorndike, L. (1955). The True Place of Astrology in the History of Science. Isis, 46(3), 273–278.

Vermij, R., & Hirai, H. (2017). The Marginalization of Astrology: Introduction. Early Science and Medicine, 22(5/6), 405–409.

Visual Sources

Cover image: Frederik de Wit. (1670). Planisphærium cœleste. [Celestial Map].

Figure 1. District Museum in Toruń. (Circa 1580). Nicolaus Copernicus. [Painting]. Wikipedia.

Figure 2. Manuscript of Aratea. (6th century CE). [Parchment manuscript]. Wikipedia.

Figure 3. NASA. Hubble Space Telescope (HST) [Photograph]. NASA.

Figure 4. Astronomical text mentioning the comet of Halley. (First millennium BCE). [Clay tablet]. Livius.org

Figure 5. Lysippus. Portrait of Alexander the Great. [Sculpture]. Wikipedia.

Figure 6. State Archive of Assyria, volume 8. University of Pennsylvania. [Book cover]. University of Pennsylvania.

Figure 7. Osama Shukir Muhammed Amin, King Esarhaddon. [Basrelief]. Wikipedia.,_671_BCE,_Pergamon_Museum.jpg

Figure 8. Klaus Wagensonner. Hellenistic horoscope, LBAT 1462. (4th-1st century BCE). [Clay tablet]. Electronic Babylonian Library.

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