CHRONOLOGY. The ancient Egyptian calendar consisted of a year of
360 days divided into the three seasons akhet (flood), peret (sowing)
and shemu (harvest), plus five extra days at the end of the year. Each
season was comprised of four months of 30 days and was in turn divided
into three weeks of 10 days of 24 hours split between night and
day. Because the calendar did not include the extra one-quarter day
of the earth’s rotation, the civil calendar gradually diverged from the
solar year so that the months moved, and the two only harmonized
briefly every 1,460 years. The solar year was measured from the annual
rising of the star Sirius, which becomes visible around July of
each year in the modern calendar.
A third calendar used for administrative purposes was the regnal
year initially based on the biennial cattle count during the Old Kingdom
and from the Middle Kingdom onward the king’s actual years,
although his first year was foreshortened, so the beginning of his second
might coincide with the beginning of the civil year. This practice
was abandoned during the New Kingdom when the full regnal year was
dated from the king’s accession, but calculation of the regnal year reverted
to the old system during the Late Period. Thus three different
dating systems—solar, civil, and regnal—were used during the New
Kingdom.
The conversion of Egyptian dates to the modern Julian calendar is
not exact. Dating from the Late Period is fixed by synchronisms
with Assyrian, Persian, Greek, and Roman dating systems. It is
known that the solar and civil calendars coincided in 139 AD, thus
the previous coincidence would have occurred 1,460 years earlier—
the period being known as a Sothic cycle—but the use of astronomical
references to the rising of the star Sirius are too unclear to be of
use. The most effective method for determining chronology is
through use of the detailed king lists known from such documents as
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