Egyptian Lunar Month

egyptian: Ꜣbd / psḏntyw

Definition

The Egyptian lunar month is the schematic 29-to-30-day cycle the Egyptians built around the phases of the Moon, running about 29.5 days on average. Its days carried their own names: day 1 was psḏntyw (the morning the old crescent has vanished and is invisible before sunrise), day 2 was Abd (the new crescent first seen), and day 15 was smdt (the half-month day, when the full Moon was most likely to fall). It ran alongside — but separately from — the fixed 365-day civil calendar.

In Tradition

Egyptologists — Parker, Clagett, Belmonte and Lull — read the lunar month as a real religious schedule of thirty named days, anchored at first-crescent invisibility (psḏntyw, day 1) and the full Moon (smdt, day 15). The moon-god Thoth governed this reckoning: psḏntyw bore the second name "Feast of Thoth" from its protective god, and Thoth, scribe of the gods, was the patron of timekeeping and lunar counting.

In Practice

When you read an Egyptian temple or funerary text, the lunar month is the grid behind its festival timing. Clagett's Document III.6 preserves the full list of thirty named feast-days, running from psḏntyw (day 1) through smdt (day 15) to the close of the month. Parker fixed the conjunction — the dark moment between old and new Moon — at mean noon on psḏntyw if the new crescent showed the next day (Abd), or at mean midnight if it was delayed to day 3 (mspr). Because the civil year had no leap day, twelve first-crescent (Abd) feasts and twelve full-Moon (smdt) feasts were pinned to it as a parallel set — the Khnumhotep II list at Beni Hassan (12th Dynasty) records them — letting moon-based worship run on top of a calendar whose own months were never lunar. Later astronomers tied 309 lunar months to 25 civil years to keep the two in step.

Historical Origin

The named lunar days are attested from the Old Kingdom offering-formulas onward and run through the New Kingdom into the Greco-Roman temple inscriptions. The canonical thirty-day list is preserved in Brugsch's Ptolemaic-era tables from Edfu and Dendera, translated by Marshall Clagett, Ancient Egyptian Science Vol II, Document III.6 (1995, pp. 281-289). The 25-year/309-month cycle survives in Papyrus Carlsberg 9. The terminology is treated in Parker, Calendars of Ancient Egypt (1950), and Belmonte and Lull, In Search of Cosmic Order (2018).

Definition

In Tradition

In Practice

Historical Origin

Further Reading