Humans have been alternatively amused, puzzled, bewildered and sometimes even terrified at the sight of this celestial phenomenon. A range of social and cultural reactions accompanies the observation of an eclipse. In ancient Mesopotamia (roughly modern Iraq), eclipses were in fact regarded as omens, as signs of things to come.

Ancient astronomers

More than two thousand years ago, the Babylonians were able to calculate that there were 38 possible eclipses within a period of 223 months: that is, about 18 years. This period of 223 months is called a Saros cycle by modern astronomers, and a sequence of eclipses separated by a Saros cycle constitutes a Saros series.

Although scientists now know that the number of lunar and solar eclipses is not exactly the same in every Saros series, one cannot underplay the achievement of Babylonian scholars in understanding this astronomical phenomenon. Their realization of this cycle eventually allowed them to predict the occurrence of an eclipse.

The level of astronomical knowledge achieved in ancient Babylon (southern Mesopotamia) cannot be separated from the astrological tradition that regarded eclipses as omens: Astronomy and astrology were then two sides of the same coin.

Rituals to preempt fate

According to Babylonian scholars, eclipses could foretell the death of the king. The conditions for an omen to be considered as such were not simple. For instance, according to a famous astronomical work known by its initial words, “Enuma Anu Enlil” — “When (the gods) Anu and Enlil” — if Jupiter was visible during the eclipse, the king was safe. Lunar eclipses seem to have been of particular concern for the well-being and survival of the king.

In order to preempt the monarch’s fate, a mechanism was devised: the “substitute king ritual,” or “sar puhi.” There are over 30 mentions of this ritual in various letters from Assyria (northern Mesopotamia), dating to the first millennium B.C. Earlier references to a similar ritual have also been found in texts in Hittite, the Indo-European language for which we have the earliest written records, dating to second-millennium Anatolia — modern-day Turkey.

In this ritual, a person would be chosen to replace the king. He would be dressed like the king and placed on the throne. To avoid confusion with a real coronation, all this would occur alongside the recitation of the negative omen triggered by the observation of the eclipse.

The real king would keep a low profile. If no additional negative portents were observed, the substitute king was put to death, therefore fulfilling the prophetic reading of the celestial omen while saving the life of the real king. This ritual would take place when an eclipse was observed or even predicted, something that became possible to do in later periods.

Looking for meaning

Mesopotamia was not unique in ascribing portentous meanings to eclipses. For instance, a chronicle of early China known as the “Bamboo Annals” refers to a total lunar eclipse that took place in 1059 B.C., during the reign of the last king of the Shang dynasty. This eclipse was regarded as a sign by a vassal king, Wen of the Zhou dynasty, to challenge his Shang overlord.

In the later account contained in the “Bamboo Annals,” an eclipse would have triggered the political and military events that marked the transition from the Shang to the Zhou dynasty in ancient China. As in the case of the Babylonian “Chronicle of Early Kings,” the “Bamboo Annals” are a history of earlier periods compiled at a later time. The “Bamboo Annals” were allegedly found in a tomb about A.D. 280, but they purport to date to the reign of the King Xiang of Wei, who died in 296 B.C.

The complexity of human events is rarely constrained and determined by one single factor. Nevertheless, whether in ancient Mesopotamia or in early China, eclipses and other omens provided contemporary justifications, or after-the-fact explanations, for an entangled set of variables that decided a specific course of history.

Even if they mix astronomy and astrology, or history with legend, humans have been preoccupied with the inescapable anomaly embodied by an eclipse for as long as they have looked at the sky.