The ancientEgyptian calendar– a civil calendar – was asolar calendarwith a 365-day year. The year consisted of three seasons of 120 days each, plus anintercalary monthof fiveepagomenal daystreated as outside of the year proper. Each season was divided into four months of 30 days. These twelve months were initially numbered within each season but came to also be known by the names of their principal festivals. Each month was divided into three 10-day periods known asdecansor decades. It has been suggested that during theNineteenth Dynastyand theTwentieth Dynastythe last two days of each decan were usually treated as a kind of weekend for the royal craftsmen, with royal artisans free from work.[2]
Because this calendrical year was nearly a quarter of a day shorter than the solar year, the Egyptian calendar lost about one day every four years relative to theGregorian calendar.It is therefore sometimes referred to as thewandering year(Latin:annus vagus), as its months rotated about one day through the solar year every four years.Ptolemy III'sCanopus Decreeattempted to correct this through the introduction of a sixth epagomenal day every four years but the proposal was resisted by the Egyptian priests and people and abandoned until the establishment of the Alexandrian orCoptic calendarbyAugustus.The introduction of aleap dayto the Egyptian calendar made it equivalent to the reformedJulian calendar,although by extension it continues to diverge from theGregorian calendarat the turn of most centuries.
Thiscivil calendarran concurrently with anEgyptian lunar calendarwhich was used for some religious rituals and festivals. SomeEgyptologistshave described it aslunisolar,with an intercalary month supposedly added every two or three years to maintain its consistency with the solar year, but no evidence of such intercalation before the4th century BChas yet been discovered.
Current understanding of the earliest development of the Egyptian calendar remains speculative. A tablet from the reign of theFirst DynastypharaohDjer(c. 3000BC) was once thought to indicate that the Egyptians had already established a link between theheliacal risingofSirius(Ancient Egyptian:SpdtorSopdet,"Triangle";Greek:Σῶθις,Sôthis) and the beginning of their year, but more recent analysis has questioned whether the tablet's picture refers to Sirius at all.[4]Similarly, based on thePalermo Stone,Alexander Scharffproposed that theOld Kingdomobserved a 320-day year, but his theory has not been widely accepted.[5]Some evidence suggests the early civil calendar had 360 days,[6]although it might merely reflect the unusual status of the fiveepagomenal daysas days "added on" to the proper year.
With its interioreffectively rainlessfor thousands of years,[7]ancient Egypt was "a gift of the river"Nile,[8]whoseannual floodingorganized the natural year into three broad natural seasons known to the Egyptians as:[9][10][11]
Emergenceor Winter (Prt,sometimes anglicized asPeret): roughly from January to May.
Low Wateror Harvest or Summer (Šmw,sometimes anglicized asShemu): roughly from May to September.[9]
As early as the reign ofDjer(c. 3000BC,Dynasty I), yearly records were being kept of the flood's high-water mark.[12]Otto E. Neugebauernoted that a 365-day year can be established by averaging a few decades of accurate observations of the Nile flood without any need forastronomical observations,[13]although the great irregularity of the flood from year to year[a]and the difficulty of maintaining a sufficiently accurateNilometerand record in prehistoric Egypt has caused other scholars to doubt that it formed the basis for the Egyptian calendar.[3][6][15]
Note that the names of the three natural seasons were incorporated into the Civil calendar year (see below), but as this calendar year is awandering year,the seasons of this calendar slowly rotate through the natural solar year, meaning that Civil season Akhet/Inundation only occasionally coincided with the Nile inundation.
The Egyptians appear to have used a purelylunar calendarprior to the establishment of the solar civil calendar[16][17]in which each month began on the morning when thewaningcrescent moon could no longer be seen.[15]Until the closing of Egypt'spolytheisttemples under theByzantines,the lunar calendar continued to be used as theliturgical yearof various cults.[17]The lunar calendar divided the month into four weeks, reflecting each quarter of thelunar phases.[18]Because the exact time of morning considered to begin the Egyptian day remains uncertain[19]and there is no evidence that any method other than observation was used to determine the beginnings of the lunar months prior to the4th century BC,[20]there is no sure way to reconstruct exact dates in the lunar calendar from its known dates.[19]The difference between beginning the day at the first light of dawn or at sunrise accounts for an 11–14 year shift in dated observations of the lunar cycle.[21]It remains unknown how the Egyptians dealt with obscurement by clouds when they occurred and the best current algorithms have been shown to differ from actual observation of the waning crescent moon in about one-in-five cases.[19]
Parkerand others have argued for its development into an observational and then calculatedlunisolar calendar[22]which used a 30 dayintercalarymonth every two to three years to accommodate thelunar year's loss of about 11 days a year relative to thesolar yearand to maintain the placement of theheliacal risingofSiriuswithin itstwelfth month.[16]No evidence for such a month, however, exists in the present historical record.[23]
A second lunar calendar is attested by ademoticastronomical papyrus[25]dating to sometime after 144 AD which outlines alunisolarcalendar operating in accordance with the Egyptian civil calendar according to a 25 year cycle.[26]The calendar seems to show its month beginning with the first visibility of the waxing crescent moon, butParkerdisplayed an error in the cycle of about a day in 500 years,[27]using it to show the cycle was developed to correspond with the new moon around 357BC.[28]This date places it prior to thePtolemaic periodand within the native EgyptianDynasty XXX.Egypt's1st Persian occupation,however, seems likely to have been its inspiration.[29]This lunisolar calendar's calculations apparently continued to be used without correction into theRoman period,even when they no longer precisely matched the observable lunar phases.[30]
The days of the lunar month — known to the Egyptians as a "temple month"[24]— were individually named and celebrated as stages in the life of the moon god, variouslyThothin theMiddle KingdomorKhonsuin thePtolemaic era:"He... is conceived... onPsḏntyw;he is born onꜢbd;he grows old afterSmdt".[31]
Sirius(bottom) andOrion(right). Together, the three brightest stars of the northern winter sky—Sirius,Betelgeuse(orange star, upper right), andProcyon(upper left)—can also be understood as forming theWinter Triangle.AMiddle Kingdomstar chartA hieroglyphic calendar atElephantine.
The civil calendar was established at some early date in or before theOld Kingdom,with probable evidence of its use early in the reign ofShepseskaf(c. 2510BC,Dynasty IV) and certain attestation during the reign ofNeferirkare(mid-25th centuryBC,Dynasty V).[54]It was probably based uponastronomical observationsofSirius[15]whosereappearance in the skyclosely corresponded to the average onset of theNile floodthrough the 5th and4th millennium BC.[14][p]A recent development is the discovery that the 30-day month of theMesopotamian calendardates as late as theJemdet Nasr Period(late 4th-millenniumBC),[56]a time Egyptian culture was borrowing various objects and cultural features from theFertile Crescent,leaving open the possibility that the main features of the calendar were borrowed in one direction or the other as well.[57]
The civil year comprised exactly 365 days,[q]divided into 12 months of 30 days each and anintercalary monthof five days,[59]which were celebrated as the birthdays of the godsOsiris,Horus,Set,Isis,andNephthys.[60]The regular months were grouped into Egypt's three seasons,[59]which gave them their original names,[61]and divided into three 10-day periods known asdecansor decades. In later sources, these were distinguished as "first", "middle", and "last".[62]It has been suggested that during theNineteenth Dynastyand theTwentieth Dynastythe last two days of each decan were usually treated as a kind of weekend for the royal craftsmen, with royal artisans free from work.[63]Dates were typically expressed in aYMD format,with apharaoh'sregnal yearfollowed by the month followed by the day of the month.[64]For example, the New Year occurred onI Akhet1.
The importance of the calendar toEgyptian religionis reflected in the use of the title "Lord of Years" (Nb Rnpt)[65]for its various creator gods.[66]Time was also considered an integral aspect ofMaat,[66]the cosmic order which opposedchaos, lies, and violence.
The civil calendar was apparently established in a year when Sirius rose on its New Year(I Akhet1)but, because of its lack ofleap years,it began to slowly cycle backwards through thesolar year.Sirius itself, about 40° below theecliptic,follows aSothic yearalmost exactly matching that of the Sun, with itsreappearancenow occurring at thelatitudeofCairo(ancientHeliopolisandMemphis) on 19July (Julian), only two or three days later than its occurrence in early antiquity.[59][67]
FollowingCensorinus[68]andMeyer,[69]the standard understanding was that, four years from the calendar's inception, Sirius would have no longer reappeared on the Egyptian New Year but on the next day(I Akhet2);four years later, it would have reappeared on the day after that; and so on through the entire calendar until its rise finally returned toI Akhet11460 years after the calendar's inception,[68][r]an event known as "apocatastasis".[70]Owing to the event's extreme regularity, Egyptian recordings of the calendrical date of the rise of Sirius have been used byEgyptologiststo fix its calendar and other events dated to it, at least to the level of the four-Egyptian-year periods which share the same date for Sirius's return, known as "tetraëterides" or "quadrennia".[70]For example, an account that Sothis rose onIII Peret1—the 181st day of the year—should show that somewhere 720, 721, 722, or 723 years have passed since the last apocatastasis.[68]Following such a scheme, the record of Sirius rising onII Shemu1in 239BC implies apocatastases on 1319 and 2779BC ±3 years.[21][s]Censorinus's placement of an apocatastasis on 21July AD139[t]permitted the calculation of its predecessors to 1322, 2782, and 4242BC.[72][failed verification]The last is sometimes described as "the first exactly dated year in history"[73]but, since the calendar is attested beforeDynasty XVIIIand the last date is now known to far predateearly Egyptian civilization,it is typically credited toDynasty IIaround the middle date.[74][u]
The classic understanding of the Sothic cycle relies, however, on several potentially erroneous assumptions. FollowingScaliger,[80]Censorinus's date is usually emended to 20July[w]but ancient authorities give a variety of 'fixed' dates for the rise of Sirius.[x]His use of the year 139 seems questionable,[83]as 136 seems to have been the start of the tetraëteris[84]and the later date chosen to flatter the birthday of Censorinus's patron.[85]Perfect observation of Sirius's actual behavior during the cycle—including its minor shift relative to the solar year—would produce a period of 1457 years; observational difficulties produce a further margin of error of about two decades.[72]Although it is certain the Egyptian day began in the morning, another four years are shifted depending on whether the precise start occurred at the first light of dawn or at sunrise.[21]It has been noted that there is no recognition in surviving records that Sirius's minor irregularities sometimes produce a triëteris or penteteris (three- or five-year periods of agreement with an Egyptian date) rather than the usual four-year periods and, given that the expected discrepancy is no more than 8 years in 1460, the cycle may have been applied schematically[70][86]according to the civil years by Egyptians and the Julian year by the Greeks and Romans.[68]The occurrence of the apocatastasis in the2nd millennium BCso close to the great political andsun-based religious reformsofAmenhotep IV/Akhenaton also leaves open the possibility that the cycle's strict application was occasionally subject to political interference.[87]The record and celebration of Sirius's rising would also vary by several days (equating to decades of the cycle) in eras when the official site of observation was moved from nearCairo.[y]The return of Sirius to the night sky varies by about a day per degree oflatitude,causing it to be seen 8–10 days earlier atAswanthan atAlexandria,[89]a difference which causesRolf Kraussto propose dating much of Egyptian history decades later than the present consensus.
Egyptian scholars were involved with the establishment ofJulius Caesar'sreformof theRoman calendar,although the Roman priests initially misapplied its formula and—by counting inclusively—added leap days every three years instead of every four. The mistake was corrected byAugustusthrough omitting leap years for a number of cycles until AD4. As the personal ruler ofEgypt,he also imposed a reform of its calendar in 26 or 25BC, possibly to correspond with the beginning of a newCallipic cycle,with the first leap day occurring on 6 Epag. in the year 22BC. This "Alexandrian calendar" corresponds almost exactly to theJulian,causing 1Thothto remain at 29August except during the year before a Julian leap year, when it occurs on 30August instead. The calendars then resume their correspondence after 4Phamenoth/ 29February of the next year.[91]
For much of Egyptian history, the months were not referred to by individual names, but were rather numbered within the three seasons.[61]As early as theMiddle Kingdom,however, each month had its own name. These finally evolved into theNew Kingdommonths, which in turn gave rise to theHellenizednames that were used forchronologybyPtolemyin hisAlmagestand by others.Copernicusconstructed his tables for the motion of the planets based on the Egyptian year because of its mathematical regularity. A convention of modernEgyptologistsis to number the months consecutively usingRoman numerals.
A persistent problem of Egyptology has been that the festivals which give their names to the months occur in the next month.Alan Gardinerproposed that an original calendar governed by the priests of Ra was supplanted by an improvement developed by the partisans of Thoth. Parker connected the discrepancy to his theories concerning the lunar calendar.Sethe,Weill,andClagettproposed that the names expressed the idea that each month culminated in the festival beginning the next.[92]
Calendars that have survived from ancient Egypt often characterise the days as either lucky or unlucky. Of the calendars recovered, the Cairo calendar is one of the best examples. Discovered in modern-dayThebes,it dates from the Ramesside Period and acts as a guide to which days were considered lucky or unlucky. Other complete calendars include Papyrus Sallier IV,[95]and the Calendar of Lucky and Unlucky Days (on the back of the Teaching of Amenemope).[96]The earliest calendars appear in theMiddle Kingdom,but they do not become codified until theNew Kingdom.It is unknown how staunchly these calendars were adhered to, as there are no references to decisions being made based on their horoscopes. Nevertheless, the different copies of the calendars are remarkably consistent with each other, with only 9.2% of the determinations of adversity or fortuitousness being due to a defined textual reason.[97]
The Calendars of Lucky and Unlucky Days seem to be based on scientific observation as well as myths.Periodicityhas been established between phases of the moon as well as the brightening and dimming of the three-star systemAlgolas visible from earth.[98]
The calendars could also be used to predict someone's future depending on the day they were born. This could also be used to predict when or how they would die. For example, people born on the tenth day of the fourth month of Akhet were predicted to die of old age.[99]
Theepagomenal dayswere added to the original 360 day calendar in order to synchronise the calendar with the approximate length of the solar year. Mythologically, these days allowed for the births of five children ofGebandNutto occur and were considered to be particularly dangerous. In particular, the daySethwas supposed to be born was considered particularly evil.[100]
The reformed Egyptian calendar continues to be used inEgyptas theCoptic calendarof theEgyptian Churchand by the Egyptian populace at large, particularly thefellah,to calculate the agricultural seasons. It differs only in its era, which is datedfrom the ascension of the Roman emperor Diocletian.Contemporary Egyptian farmers, like their ancient predecessors, divide the year into three seasons: winter, summer, and inundation.
^In the 30 years prior to the completion of theAswan Low Damin 1902, the period between Egypt's "annual" floods varied from 335 to 415 days,[3]with the first rise starting as early as 15 April and as late as 23 June.[14]
are shrunk and fit under the two sides of the standard
.
^Other possibilities for the original basis of the calendar include comparison of a detailed record of lunar dates against the rising of Sirius over a 40 year span, discounted byNeugebaueras likely to produce a calendar more accurate than the actual one;[13]his own theory (discussed above) that the timing of successivefloodswere averaged over a few decades;[13]and the theory that the position of the solar rising was recorded over a number of years, permitting comparison of the timing of the solstices over the years. Apredynasticpetroglyphdiscovered by theUniversity of South Carolina's expedition atNekhenin 1986 may preserve such a record, if it had been moved about 10° from its original position prior to discovery.[55]
^It has been argued that theEbers Papyrusshows a fixed calendar incorporatingleap years,but this is no longer believed.[58]
^1460Julian years(exactly) orGregorian years(roughly) in modern calculations, equivalent to 1461 Egyptian civil years, but apparently reckoned as 1460 civil years (1459 Julian years) by the ancient Egyptians themselves.[68]
^PerO'Mara,actually ±16 years when including the other factors affecting the calculated Sothic year.[21]
^UsingRoman dating,he said of the relevant New Year that "when the emperorAntoninus Piuswas consul of Rome for a second time withBruttius Praesensthis same day coincided with the13th daybefore thecalendsof August "(Latin:cum... imperatore quinque hoc anno fuit Antonino Pio II Bruttio Praesente Romae consulibus idem dies fuerit ante diem XII kal. Aug.).[71]
^Meyerhimself accepted the earliest date,[74]though before theMiddle Chronologywas shown to be more likely than theshortor longchronologies of the Middle East.Parkerargued for its introductionaheadof apocatastasis on the middle date based on his understanding of its development from a Sothic-based lunar calendar. He placed its introduction within the rangec. 2937– c. 2821BC, noting it was more likely in theDynasty IIpart of the range.[75][76]
^Specifically, the calculations are for 30°N with no adjustment for clouds and an averaged amount of aerosols for the region. In practice, clouds or other obscurement and observational error may have shifted any of these calculated values by a few days.[72]
^This seems to be the case, for example, with astronomical records of theXVIII Dynastyand its successors, including the Ebers Papyrus, which seem to have been made atThebesrather than Heliopolis.[88]
^Englund, Robert K. (1988), "Administrative Timekeeping in Ancient Mesopotamia",Journal of the Economic and Social History of the Orient,No. 31,pp. 121–185.
Grafton, Anthony Thomas;et al. (1985), "Technical Chronology and Astrological History in Varro, Censorinus, and Others",The Classical Quarterly,Vol. XXXV, No. 2,pp. 454–465.
Krauss, Rolf; et al., eds. (2006),Ancient Egyptian Chronology,Handbook of Oriental Studies,Sect. 1, Vol. 83, Leiden: Brill.
Luft, Ulrich (2006), "Absolute Chronology in Egypt in the First Quarter of the Second Millennium BC",Egypt and the Levant,Vol. XVI,Austrian Academy of Sciences Press, pp. 309–316.
Neugebauer, Otto Eduard(1939), "Die Bedeutungslosigkeit der 'Sothisperiode' für die Älteste Ägyptische Chronologie",Acta Orientalia,No. 16,pp. 169 ff.(in German)
O'Mara, Patrick F. (January 2003), "Censorinus, the Sothic Cycle, and Calendar Year One in Ancient Egypt: The Epistemological Problem",Journal of Near Eastern Studies,Vol. LXII, No. 1,Chicago: University of Chicago Press, pp. 17–26.
CalendricaIncludes the Egyptian civil calendar with years inPtolemy's Nabonassar Era (year 1 = 747 BC) as well as the Coptic, Ethiopic, and French calendars.
Civil, ver. 4.0,is a 25kB DOS program to convert dates in the Egyptian civil calendar to the Julian or Gregorian ones
