less on the same dates; the differences between them would have been mainly
only nomenclatural. These calendars lent themselves much better to a process
of unification and homogenization than in Greece, where months were often
erratic and lunar only in name, and where calendars were consequently far
more diverse.
Unlike the Greek calendars, as stated, the standard Babylonian calendar was
rigorously lunar: its month always began on the evening when the new moon
crescent wasfirst visible or within no more than one day of it, and month-
lengths were restricted to 29 or 30 days. The Greek practice of adding or
suppressing days to the month, and hence of deviating from the true lunar
month, was alien to the Babylonian calendar. This does not mean, however,
that the Babylonian calendar was devoid of anyflexibility and unpredictability.
First visibility of the new moon is a complex phenomenon that does not recur
at regular or easily predictable intervals; there is no regular alternation, for
example, of 29- and 30-day lunar months. For this reason, the determination
of the Babylonian month was largely dependent on monthly, empirical sight-
ings of the new moon, which would have been subject to a number of
unpredictable factors such as poor atmospheric and visibility conditions.
Furthermore, the intercalation of a thirteenth month in the year, necessary
for lunisolar synchronism, was an important aspect of the Babylonian calen-
dar that could be subject to someflexibility and unpredictability. Overall,
however, the Babylonian calendar was considerably more regular than the
Greek calendars.
This distinctive regularity was only to increase in the course of thefirst
millenniumBCE. During this period, techniques for predicting new moon
visibility were developed and used, increasingly, for the advance determina-
tion of the length of months; whilst the intercalation of the year became
regularized and eventually cyclical andfixed. These predictive techniques
and cycles, and the resulting regularity of the standard Babylonian calendar,
were clearly related to the Mesopotamian tradition of astronomy, observation-
al and (later) mathematical. Indeed, by the neo-Assyrian period, but probably
already much earlier, astronomical experts variously identified in modern
scholarship as ‘scholars’, ‘astrologers’,or‘astronomers’—I shall refer to
them, purely for convenience, as‘astrologers’—were closely involved in the
determination of the months and of the intercalation. In Assyria, in the neo-
Assyrian period, some astrologers were directly associated with the imperial
court; in Babylonia they were primarily temple officials whose importance in
the great temples rose further in the Persian and Seleucid periods.^7 Either way,
(^7) Brown (2000) 41–7, Rochberg (2010) 245, 248–53.‘Astrologers’are referred to in the
sources as:tupšarruenūma anuenlil, literally‘scribes of the astrological compendium Enūma
Anu Enlil’, though this term is relatively rare, and other, more general titles are also used. The
term:tupšaritself has a broader meaning than‘scribe’, as it is also used for scholars and high
The Babylonian Calendar 73