- Since all celestial observations in Mesopotamia served divinatory purposes—to discover the hidden meaning of divine messages inscribed in the movements of stars and planets—the two terms are inseparable. The primarily esoteric purpose did not preclude very detailed, regular, and “scientific” measurements and calculations. Astral and planetary phenomena were only one part of a whole range of observable subjects that included the behavior of animals and human beings, the layout of cities, malformations of organs or fetuses, prices of staple commodities, war, famines, and so forth. The principle was that deviations from a perceived “normality” were inherently “ominous” and had either positive or negative connotations. The collection and interpretation of such spontaneously occurring omens, as opposed to those solicited in specific rituals, was the task of highly trained scribes. They compiled lists of omens, in series covering different categories, with a column of text providing the interpretation. To establish astronomical “regularity,” planetary and astral data were collected and collated. The scholars aimed to include all possible permutation of phenomena and encoded them in such a way that they could be meaningfully decoded when unusual celestial events occurred.The earliest celestial series date from the Old Babylonian period, from around 1700 B.C. They chart not only unusual astral phenomena but also weather patterns at the time of observation. The collection of data kept growing and was compiled in a work called Enuma Anu Enlil, after its initial words. Copies were found in the library of Ashurbanipal at Nineveh. The entries concentrate on omens for the king and the country (e.g., “If the sun is surrounded by a halo and a cloud bank lies on the right, there will be a catastrophe everywhere in the country”).Lunar and solar eclipses were considered particularly ominous. It was crucial for diviners to predict the timing of an eclipse in time for apotropaic rituals averting any evil influence to be performed. The so-called mathematical-astronomical texts (MUL.APIN “The Plough-Star”) from the last centuries of the first millennium B.C. incorporate methods whereby such phenomena could be predicted to a high level of accuracy.During the Achaemenid period, divinatory practices became less popular and individual predictions were solicited, which led to the introduction of the horoscope in the Seleucid period, perhaps as a Greek influence. ABabylonian invention was the assignment of four groups of zodiacal signs to the moon, Saturn, and Mars. Astronomical diaries, recording lunar, planetary, meteorological, and economic data were kept well into the Christian era.
Historical Dictionary of Mesopotamia. EdwART. 2012.