simanu (Babylonian seasonal hour)

Definition

Simanu is the Akkadian term used in the Babylonian horoscopes for a seasonal hour — one of twelve equal divisions of either daylight or night whose number stays fixed at twelve but whose absolute length varies through the year because day-length and night-length vary with the seasons. In horoscope contexts the simanu are designated by ordinal numbers (e.g. "7 simanu" = the 7th simanu), and the formula ina nth siman, "in the nth hour," records the time of birth, with U₄ or GE₆ distinguishing diurnal from nocturnal hours.

In Tradition

Rochberg, Hunger and Pingree treat the simanu as a distinct Babylonian timekeeping unit — the seasonal-hour time-of-day measure used in the horoscope corpus — and distinguish it from the bēru, the twelve-fold spatial division of the sky-circle. Rochberg situates the seasonal hour in a dedicated Centaurus 32 (1989) study; the system is first attested in a seventh-century BCE Neo-Babylonian arithmetical scheme and is later carried into the horoscopes for noting birth-hour.

In Practice

For the reader of a Babylonian horoscope, the simanu is the unit by which the native's time of birth is fixed inside the day- or night-half. Because only the Moon's position is greatly affected by a change of hour, the simanu of birth is not noted in every horoscope; where given it follows the convention ina simanisu, "in his (hour of) birth." The simanu differs from the bēru even though both divide the cosmic frame into twelve: simanu partitions the variable interval of daylight or night into twelve equal fractions that change length through the year, while bēru partitions the 360° celestial circle into twelve fixed 30° arcs. The seasonal-hour scheme — together with the constant-length UŠ/bēru system and the Egyptian-derived equinoctial hour — gives the Babylonian horoscope-genre three coexisting time-frames, each applied where its arithmetic is convenient. On Hunger and Pingree's analysis the seasonal-hour scheme reached Mesopotamia no later than the seventh century BCE, continuous with older Egyptian twelfth-part day-and-night division.

Historical Origin

First attested in a Neo-Babylonian seventh-century BCE arithmetical scheme on the seasonal-hour count; carried through the Late-Babylonian horoscope corpus (~410 BCE through ~50 BCE). Modern critical treatments: Francesca Rochberg, *Babylonian Horoscopes* (American Philosophical Society 1998) Ch. 1 §2 pp. 6-7 and Ch. 2 §2.3.3 pp. 37-38, citing her own "Babylonian Seasonal Hours" Centaurus 32 (1989) pp. 146-170; Rochberg, *The Heavenly Writing* (2004) Ch. 3 §3.1 pp. 134-135; Hermann Hunger & David Pingree, *Astral Sciences in Mesopotamia* (1999) §A.8 pp. 130-134.

Further Reading

• Francesca Rochberg, Babylonian Horoscopes
• Francesca Rochberg, The Heavenly Writing: Divination, Horoscopy, and Astronomy in Mesopotamian Culture
• Hermann Hunger & David Pingree, Astral Sciences in Mesopotamia