Babylonian astronomy refers to the systematic observation, recording, and mathematical analysis of celestial phenomena carried out in ancient Mesopotamia, primarily from roughly 1800 BCE through the first century BCE. Practiced by trained scribes and priests operating under institutional sponsorship, it represents one of the earliest sustained traditions of empirical sky-watching in recorded history. The corpus includes observations of planetary movements, lunar and solar eclipses, fixed stars, and atmospheric phenomena, preserved on clay tablets inscribed in cuneiform script. Babylonian astronomy is distinct from - though related to - Babylonian astrology, with which it shared methods, personnel, and texts.

Babylonian astronomers worked within temple institutions, particularly in cities such as Babylon, Nippur, Uruk, and Sippar. Their primary tools were naked-eye observation and written record-keeping; no optical instruments are attested. Over centuries, the accumulation of observational records enabled the identification of recurring celestial cycles, most notably the Saros cycle of approximately 18 years governing the recurrence of eclipses, and the 19-year Metonic cycle relating lunar months to solar years. By the late period (roughly 400-50 BCE), Babylonian scholars had developed arithmetical schemes - now called System A and System B by modern historians - capable of predicting the positions and phases of the Moon and planets with considerable accuracy. These predictive methods used tabular arithmetic rather than geometric models, distinguishing the Babylonian approach from the later geometrical methods of Greek astronomy.

The primary surviving text genres include the Enuma Anu Enlil, a large compendium of omen texts associating celestial events with terrestrial outcomes; the Astronomical Diaries, a continuous series of observational records spanning roughly 750 to 60 BCE; goal-year texts, which used past observations to project future phenomena; and ephemerides, tables of computed planetary and lunar positions.

The degree to which Babylonian methods and data influenced the development of Greek mathematical astronomy is a subject of active scholarship. It is well established that Hellenistic astronomers, including Hipparchus, had access to Babylonian period relations and observational records, and that specific numerical parameters in Greek astronomical texts derive from Babylonian sources. The extent of direct transmission versus independent development, and the mechanisms by which knowledge moved between the two traditions, remain topics of scholarly discussion. See Babylonian-Greek Astronomical Transmission for a fuller treatment.

Babylonian astronomical practice was institutionally and conceptually intertwined with celestial divination. Observations were recorded and predictions made in part to anticipate omens bearing on the king and the state. Whether this relationship means Babylonian astronomy should be classified as a science, a proto-science, or a ritual-divinatory practice is a framing question that historians of science have approached differently. See Babylonian Astronomy - Scientific Status Debate for a discussion of these positions.

There is broad consensus among historians of mathematics and astronomy that Babylonian scholars developed genuine predictive mathematical techniques independent of Greek geometrical methods, and that these techniques achieved high numerical accuracy for lunar and planetary phenomena. See Babylonian Astronomy - History of Science Consensus.

• Autonomous scientific tradition - Some historians characterize Babylonian astronomy as a fully independent scientific tradition that should be evaluated on its own terms, not as a precursor or inferior alternative to Greek astronomy. See Autonomous Tradition Viewpoint-viewpoint.
• Proto-scientific or pre-scientific practice - Others situate Babylonian astronomy within a broader divinatory framework and argue that the absence of physical or geometrical models of the cosmos limits its classification as science in a strict sense. See Proto-Scientific Viewpoint.
• Foundational to Western astronomy - A third position emphasizes the transmission of Babylonian period relations and data to Greek astronomers as a necessary precondition for the later development of mathematical astronomy in the Hellenistic world. See Foundational to Western Astronomy Viewpoint.

• Babylonian Astronomy - History
• Babylonian Astronomy - Scientific Status Debate
• Babylonian-Greek Astronomical Transmission
• Babylonian Astronomy - History of Science Consensus
• Mesopotamian Mathematics
• Babylonian Astrology
• Enuma Anu Enlil
• Astronomical Diaries
• Greek Astronomy

1. Neugebauer, Otto. Astronomical Cuneiform Texts. 3 vols. London: Lund Humphries, 1955.
2. Neugebauer, Otto. A History of Ancient Mathematical Astronomy. 3 vols. Berlin: Springer, 1975.
3. Hunger, Hermann, and David Pingree. Astral Sciences in Mesopotamia. Leiden: Brill, 1999.
4. Rochberg, Francesca. The Heavenly Writing: Divination, Horoscopy, and Astronomy in Mesopotamian Culture. Cambridge: Cambridge University Press, 2004.
5. Jones, Alexander. “The Adaptation of Babylonian Methods in Greek Numerical Astronomy.” Isis 82, no. 3 (1991): 441-453.
6. Swerdlow, N. M. The Babylonian Theory of the Planets. Princeton: Princeton University Press, 1998.