HOME
The Info List - Julian Calendar


--- Advertisement ---



The Julian calendar, proposed by Julius Caesar
Julius Caesar
in 46 BC (708 AUC), was a reform of the Roman calendar.[1] It took effect on 1 January
January
45 BC (AUC 709), by edict. It was the predominant calendar in the Roman world, most of Europe, and in European settlements in the Americas and elsewhere, until it was refined and gradually replaced by the Gregorian calendar, promulgated in 1582 by Pope Gregory XIII. The Julian calendar
Julian calendar
gains against the mean tropical year at the rate of one day in 128 years. For the Gregorian calendar, the figure is one day in 3,030 years.[2] The difference in the average length of the year between Julian (365.25 days) and Gregorian (365.2425 days) is 0.002%. The Julian calendar
Julian calendar
has a regular year of 365 days divided into 12 months, as listed in the table below. A leap day is added to February every four years. The Julian year is, therefore, on average 365.25 days long. It was intended to approximate the tropical (solar) year. Although Greek astronomers had known, at least since Hipparchus, a century before the Julian reform, that the tropical year was slightly shorter than 365.25 days, the calendar did not compensate for this difference. As a result, the calendar year gains about three days every four centuries compared to observed equinox times and the seasons. This discrepancy was corrected by the Gregorian reform of 1582. The Gregorian calendar
Gregorian calendar
has the same months and month lengths as the Julian calendar, but, in the Gregorian calendar, years evenly divisible by 100 are not leap years, except that years evenly divisible by 400 remain leap years.[3] Consequently—since 16 February
February
Julian/1 March
March
1900 Gregorian and until 15 February
February
Julian/28 February
February
2100 Gregorian—the Julian calendar
Julian calendar
is currently 13 days behind the Gregorian calendar. The Julian calendar
Julian calendar
has been replaced as the civil calendar by the Gregorian calendar
Gregorian calendar
in almost all countries which formerly used it, although it continued to be the civil calendar of some countries into the 20th century.[4] Egypt converted on 20 December
December
1874/1 January 1875. Turkey
Turkey
switched (for fiscal purposes) on 16 February/1 March 1917. Russia
Russia
changed on 1/14 February
February
1918.[5] Greece made the change for civil purposes on 16 February/1 March
March
1923, but the national day (25 March), which was a religious holiday, was to remain on the old calendar. Most Christian denominations in the west and areas evangelised by western churches have also replaced the Julian calendar with the Gregorian as the basis for their liturgical calendars. However, most branches of the Eastern Orthodox Church
Orthodox Church
still use the Julian calendar
Julian calendar
for calculating the date of Easter, upon which the timing of all the other moveable feasts depends. Some Orthodox churches have adopted the Revised Julian calendar
Revised Julian calendar
for the observance of fixed feasts, while other Orthodox churches retain the Julian calendar for all purposes.[6] The Julian calendar
Julian calendar
is still used by the Berbers
Berbers
of the Maghreb in the form of the Berber calendar,[7] and on Mount Athos. In the form of the Alexandrian calendar, it is the basis for the Ethiopian calendar, which is the civil calendar of Ethiopia. During the changeover between calendars and for some time afterwards, dual dating was used in documents and gave the date according to both systems. In contemporary as well as modern texts that describe events during the period of change, it is customary to clarify to which calendar a given date refers by using an O.S. or N.S. suffix (denoting Old Style, Julian or New Style, Gregorian).

Contents

1 Table of months 2 Motivation 3 Context of the reform 4 Julian reform

4.1 Realignment of the year 4.2 Changes to the months 4.3 Intercalation 4.4 Sacrobosco's theory on month lengths 4.5 Adoption of the Julian calendar

5 Leap year
Leap year
error 6 Month
Month
names 7 Year
Year
numbering 8 New Year's Day 9 From Julian to Gregorian 10 Eastern Orthodox usage 11 See also 12 Notes 13 Bibliography 14 External links

Table of months

Months (Roman) Lengths before 45 BC Lengths as of 45 BC Months (English)

Ianuarius[8] 29 31 January

Februarius 28 (in common years) In intercalary years: 23 if Intercalaris is variable 23/24 if Intercalaris is fixed 28 (leap years: 29) February

Martius 31 31 March

Aprilis 29 30 April

Maius 31 31 May

Iunius[8] 29 30 June

Quintilis[9] (Iulius) 31 31 July

Sextilis
Sextilis
(Augustus) 29 31 August

September 29 30 September

October 31 31 October

November 29 30 November

December 29 31 December

Motivation The ordinary year in the previous Roman calendar
Roman calendar
consisted of 12 months, for a total of 355 days. In addition, a 27- or 28-day intercalary month, the Mensis Intercalaris, was sometimes inserted between February
February
and March. This intercalary month was formed by inserting 22 or 23 days after the first 23 days of February; the last five days of February, which counted down toward the start of March, became the last five days of Intercalaris. The net effect was to add 22 or 23 days to the year, forming an intercalary year of 377 or 378 days.[10] Some say the mensis intercalaris always had 27 days and began on either the first or the second day after the Terminalia (23 February).[11] According to the later writers Censorinus and Macrobius, the ideal intercalary cycle consisted of ordinary years of 355 days alternating with intercalary years, alternately 377 and 378 days long. In this system, the average Roman year would have had ​366 1⁄4 days over four years, giving it an average drift of one day per year relative to any solstice or equinox. Macrobius
Macrobius
describes a further refinement whereby, in one 8-year period within a 24-year cycle, there were only three intercalary years, each of 377 days (thus 11 intercalary years out of 24). This refinement averages the length of the year to 365.25 days over 24 years. In practice, intercalations did not occur systematically according to any of these ideal systems, but were determined by the pontifices. So far as can be determined from the historical evidence, they were much less regular than these ideal schemes suggest. They usually occurred every second or third year, but were sometimes omitted for much longer, and occasionally occurred in two consecutive years. If managed correctly this system could have allowed the Roman year to stay roughly aligned to a tropical year. However, since the pontifices were often politicians, and because a Roman magistrate's term of office corresponded with a calendar year, this power was prone to abuse: a pontifex could lengthen a year in which he or one of his political allies was in office, or refuse to lengthen one in which his opponents were in power.[12] If too many intercalations were omitted, as happened after the Second Punic War and during the Civil Wars, the calendar would drift out of alignment with the tropical year. Moreover, because intercalations were often determined quite late, the average Roman citizen often did not know the date, particularly if he were some distance from the city. For these reasons, the last years of the pre-Julian calendar were later known as "years of confusion". The problems became particularly acute during the years of Julius Caesar's pontificate before the reform, 63–46 BC, when there were only five intercalary months (instead of eight), none of which were during the five Roman years before 46 BC. Caesar's reform was intended to solve this problem permanently, by creating a calendar that remained aligned to the sun without any human intervention. This proved useful very soon after the new calendar came into effect. Varro
Varro
used it in 37 BC to fix calendar dates for the start of the four seasons, which would have been impossible only 8 years earlier.[13] A century later, when Pliny dated the winter solstice to 25 December
December
because the sun entered the 8th degree of Capricorn on that date,[14] this stability had become an ordinary fact of life. Context of the reform Although the approximation of ​365 1⁄4 days for the tropical year had been known for a long time[15] ancient solar calendars had used less precise periods, resulting in gradual misalignment of the calendar with the seasons. The octaeteris, a cycle of 8 lunar years popularised by Cleostratus (and also commonly attributed to Eudoxus) which was used in some early Greek calendars, notably in Athens, is 1.53 days longer than eight Julian years. The length of nineteen years in the cycle of Meton was 6,940 days, six hours longer than the mean Julian year. The mean Julian year was the basis of the 76-year cycle devised by Callippus (a student under Eudoxus) to improve the Metonic cycle. In Persia (Iran) after the reform in the Persian calendar by introduction of the Persian Zoroastrian (i. e. Young Avestan) calendar in 503 BC and afterwards, the first day of the year (1 Farvardin=Nowruz) slipped against the vernal equinox at the rate of approximately one day every four years.[16][17] Likewise in the Egyptian calendar, a fixed year of 365 days was in use, drifting by one day against the sun in four years. An unsuccessful attempt to add an extra day every fourth year was made in 238 BC (Decree of Canopus). Caesar probably experienced this "wandering" or "vague" calendar in that country. He landed in the Nile delta in October
October
48 BC and soon became embroiled in the Ptolemaic dynastic war, especially after Cleopatra managed to be "introduced" to him in Alexandria. Caesar imposed a peace, and a banquet was held to celebrate the event.[18] Lucan
Lucan
depicted Caesar talking to a wise man called Acoreus during the feast, stating his intention to create a calendar more perfect than that of Eudoxus[18] (Eudoxus was popularly credited with having determined the length of the year to be ​365 1⁄4 days).[19] But the war soon resumed and Caesar was attacked by the Egyptian army for several months until he achieved victory. He then enjoyed a long cruise on the Nile with Cleopatra before leaving the country in June
June
47 BC.[20] Caesar returned to Rome
Rome
in 46 BC and, according to Plutarch, called in the best philosophers and mathematicians of his time to solve the problem of the calendar.[21] Pliny says that Caesar was aided in his reform by the astronomer Sosigenes of Alexandria[22] who is generally considered the principal designer of the reform. Sosigenes may also have been the author of the astronomical almanac published by Caesar to facilitate the reform.[23] Eventually, it was decided to establish a calendar that would be a combination between the old Roman months, the fixed length of the Egyptian calendar, and the ​365 1⁄4 days of the Greek astronomy. According to Macrobius, Caesar was assisted in this by a certain Marcus Flavius.[24] Julian reform Realignment of the year The first step of the reform was to realign the start of the calendar year (1 January) to the tropical year by making 46 BC (708 AUC) 445 days long, compensating for the intercalations which had been missed during Caesar's pontificate. This year had already been extended from 355 to 378 days by the insertion of a regular intercalary month in February. When Caesar decreed the reform, probably shortly after his return from the African campaign in late Quintilis
Quintilis
(July), he added 67 more days by inserting two extraordinary intercalary months between November
November
and December.[25] These months are called Intercalaris Prior and Intercalaris Posterior in letters of Cicero
Cicero
written at the time; there is no basis for the statement sometimes seen that they were called "Undecimber" and "Duodecimber", terms that arose in the 18th century over a millennium after the Roman Empire's collapse.[26] Their individual lengths are unknown, as is the position of the Nones and Ides within them.[27] Because 46 BC was the last of a series of irregular years, this extra-long year was, and is, referred to as the "last year of confusion". The new calendar began operation after the realignment had been completed, in 45 BC.[28] Changes to the months The Julian months were formed by adding ten days to a regular pre-Julian Roman year of 355 days, creating a regular Julian year of 365 days. Two extra days were added to January, Sextilis
Sextilis
(August) and December, and one extra day was added to April, June, September
September
and November. February
February
was not changed in ordinary years, and so continued to be the traditional 28 days. Thus, the ordinary (i.e., non-leap year) lengths of all of the months were set by the Julian calendar
Julian calendar
to the same values they still hold today. (See Sacrobosco's theory on month lengths below for stories purporting otherwise.) The Julian reform did not change the method used to account days of the month in the pre-Julian calendar, based on the Kalends, Nones and Ides, nor did it change the positions of these three dates within the months. Macrobius
Macrobius
states that the extra days were added immediately before the last day of each month to avoid disturbing the position of the established religious ceremonies relative to the Nones and Ides of the month.[29] However, since Roman dates after the Ides of the month counted down toward the start of the next month, the extra days had the effect of raising the initial value of the count of the day following the Ides in the lengthened months. Thus, in January, Sextilis
Sextilis
and December
December
the 14th day of the month became a.d. XIX Kal. instead of a.d. XVII Kal., while in April, June, September
September
and November
November
it became a.d. XVIII Kal. Romans of the time born after the Ides of a month responded differently to the effect of this change on their birthdays. Mark Antony kept his birthday on 14 January, which changed its date from a.d. XVII Kal. Feb to a.d. XIX Kal. Feb, a date that had previously not existed. Livia
Livia
kept the date of her birthday unchanged at a.d. III Kal. Feb., which moved it from 28 to 30 January, a day that had previously not existed. Augustus
Augustus
kept his on 23 September, but both the old date (a.d. VIII Kal. Oct.) and the new (a.d. IX Kal. Oct.) were celebrated in some places. The inserted days were all initially characterised as dies fasti (F – see Roman calendar).[30] The character of a few festival days was changed. In the early Julio- Claudian
Claudian
period a large number of festivals were decreed to celebrate events of dynastic importance, which caused the character of the associated dates to be changed to NP. However, this practice was discontinued around the reign of Claudius, and the practice of characterising days fell into disuse around the end of the first century AD: the Antonine jurist Gaius speaks of dies nefasti as a thing of the past.[31] Intercalation The old intercalary month was abolished. The new leap day was dated as ante diem bis sextum Kalendas Martias ('the sixth doubled before the Kalends of March'), usually abbreviated as a.d. bis VI Kal. Mart.; hence it is called in English the bissextile day. The year in which it occurred was termed annus bissextus, in English the bissextile year. There is debate about the exact position of the bissextile day in the early Julian calendar. The earliest direct evidence is a statement of the 2nd century jurist Celsus, who states that there were two halves of a 48-hour day, and that the intercalated day was the "posterior" half. An inscription from AD 168 states that a.d. V Kal. Mart. was the day after the bissextile day. The 19th century chronologist Ideler argued that Celsus used the term "posterior" in a technical fashion to refer to the earlier of the two days, which requires the inscription to refer to the whole 48-hour day as the bissextile. Some later historians share this view. Others, following Mommsen, take the view that Celsus was using the ordinary Latin
Latin
(and English) meaning of "posterior". A third view is that neither half of the 48-hour "bis sextum" was originally formally designated as intercalated, but that the need to do so arose as the concept of a 48-hour day became obsolete.[32] There is no doubt that the bissextile day eventually became the earlier of the two days for most purposes. In 238 Censorinus stated that it was inserted after the Terminalia (23 February) and was followed by the last five days of February, i.e., a.d. VI, V, IV, III and prid. Kal. Mart. (which would be 24 to 28 February
February
in a common year and the 25th to 29th in a leap year). Hence he regarded the bissextum as the first half of the doubled day. All later writers, including Macrobius
Macrobius
about 430, Bede
Bede
in 725, and other medieval computists (calculators of Easter) followed this rule, as does the liturgical calendar of the Roman Catholic Church. However, Celsus' definition continued to be used for legal purposes. It was incorporated into Justinian's Digest,[33] and in the English statute De anno et die bissextili of 1236,[34] which was not formally repealed until 1879. The effect of the bissextile day on the nundinal cycle is not discussed in the sources. According to Dio Cassius, a leap day was inserted in 41 BC to ensure that the first market day of 40 BC did not fall on 1 January, which implies that the old 8-day cycle was not immediately affected by the Julian reform. However, he also reports that in AD 44, and on some previous occasions, the market day was changed to avoid a conflict with a religious festival. This may indicate that a single nundinal letter was assigned to both halves of the 48-hour bissextile day by this time, so that the Regifugium and the market day might fall on the same date but on different days. In any case, the 8-day nundinal cycle began to be displaced by the 7-day week in the first century AD, and dominical letters began to appear alongside nundinal letters in the fasti.[35] During the late Middle Ages
Middle Ages
days in the month came to be numbered in consecutive day order. Consequently, the leap day was considered to be the last day in February
February
in leap years, i.e., 29 February, which is its current position. Sacrobosco's theory on month lengths The Julian reform set the lengths of the months to their modern values. However, a 13th-century scholar, Sacrobosco, proposed a different explanation for the lengths of Julian months[36] which is still widely repeated but is certainly wrong. According to Sacrobosco, the month lengths for ordinary years in the Roman Republican calendar, from January
January
to December, were:

30, 29, 30, 29, 30, 29, 30, 29, 30, 29, 30, 29.

Sacrobosco
Sacrobosco
then thought that Julius Caesar
Julius Caesar
added one day to every month except February, a total of 11 more days to regular months, giving the ordinary Julian year of 365 days. A single leap day could now be added to this extra short February:

31, 29/30, 31, 30, 31, 30, 31, 30, 31, 30, 31, 30.

He then said Augustus
Augustus
changed this, by taking one day from February
February
to add it to Sextilis, and then modifying the alternation of the following months, to:

31, 28/29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31

so that the length of Augustus
Augustus
(August) would not be shorter than (and therefore inferior to) the length of Iulius (July), giving us the irregular month lengths which are still in use. There is abundant evidence disproving this theory. First, a wall painting of a Roman calendar
Roman calendar
predating the Julian reform has survived,[37] which confirms the literary accounts that the months were already irregular before Julius Caesar
Julius Caesar
reformed them, with an ordinary year of 355 days, not 354, with month lengths arranged as:

29, 28, 31, 29, 31, 29, 31, 29, 29, 31, 29, 29.

Also, the Julian reform did not change the dates of the Nones and Ides. In particular, the Ides were late (on the 15th rather than 13th) in March, May, July
July
and October, showing that these months always had 31 days in the Roman calendar,[38] whereas Sacrobosco's theory requires that March, May
May
and July
July
were originally 30 days long and that the length of October
October
was changed from 29 to 30 days by Caesar and to 31 days by Augustus. Further, Sacrobosco's theory is explicitly contradicted by the 3rd and 5th century authors Censorinus[39] and Macrobius,[40] and it is inconsistent with seasonal lengths given by Varro, writing in 37 BC,[13] before Sextilis
Sextilis
was renamed for Augustus
Augustus
in 8 BC, with the 31-day Sextilis
Sextilis
given by an Egyptian papyrus from 24 BC,[41] and with the 28-day February
February
shown in the Fasti
Fasti
Caeretani, which is dated before 12 BC.[42] Adoption of the Julian calendar

This section needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. ( December
December
2013) (Learn how and when to remove this template message)

Caesar's reform only applied to the Roman calendar. However, in the following decades many of the local civic and provincial calendars of the empire and neighbouring client kingdoms were aligned to the Julian calendar by transforming them into calendars with years of 365 days with an extra day intercalated every four years.[43] The reformed calendars typically retained many features of the unreformed calendars. In many cases, the New Year
Year
was not on 1 January, the leap day was not on the bissextile day, the old month names were retained, the lengths of the reformed months did not match the lengths of Julian months, and, even if they did, their first days did not match the first day of the corresponding Julian month. Nevertheless, since the reformed calendars had fixed relationships to each other and to the Julian calendar, the process of converting dates between them became quite straightforward, through the use of conversion tables known as hemerologia.[44] Several of the reformed calendars are only known through surviving hemerologia. The three most important of these calendars are the Alexandrian calendar, the Asian calendar and the Syro-Macedonian calendar. Other reformed calendars are known from Cappadocia, Cyprus and the cities of Syria and Palestine. Most reformed calendars were adopted under Augustus, though the calendar of Nabatea
Nabatea
was reformed after the kingdom became the Roman province
Roman province
of Arabia in AD 106. There is no evidence that local calendars were aligned to the Julian calendar
Julian calendar
in the western empire. Unreformed calendars continued to be used in Gaul, Greece, Macedon, the Balkans and parts of Palestine, most notably in Judea. The Alexandrian calendar
Alexandrian calendar
adapted the Egyptian calendar
Egyptian calendar
by adding a 6th epagomenal day as the last day of the year in every fourth year, falling on 29 August
August
preceding a Julian bissextile day. It was otherwise identical to the Egyptian calendar. The first leap day was in 22 BC, and they occurred every four years from the beginning, even though Roman leap days occurred every three years at this time (see Leap year
Leap year
error). This calendar influenced the structure of several other reformed calendars, such as those of the cities of Gaza and Ascalon in Palestine, Salamis in Cyprus, and the province of Arabia. It was adopted by the Coptic church and remains in use both as the liturgical calendar of the Coptic church and as the civil calendar of Ethiopia. The Asian calendar was an adaptation of the Macedonian calendar used in the province of Asia and, with minor variations, in nearby cities and provinces. It is known in detail through the survival of decrees promulgating it issued in 8 BC by the proconsul Paullus Fabius Maximus. It renamed the first month Dios as Kaisar, and arranged the months such that each month started on the ninth day before the kalends of the corresponding Roman month; thus the year began on 23 September, Augustus' birthday. Since Greek months typically had 29 or 30 days, the extra day of 31-day months was named Sebaste—the emperor's day—and was the first day of these months. The leap day was a second Sebaste day in the month of Xandikos, i.e., 24 February. This calendar remained in use at least until the middle of the fifth century AD. The Syro-Macedonian calendar was an adaptation of the Macedonian calendar used in Antioch
Antioch
and other parts of Syria. The months were exactly aligned to the Julian calendar, but they retained their Macedonian names and the year began in Dios = November
November
until the fifth century, when the start of the year was moved to Gorpiaios = September. These reformed calendars generally remained in use until the fifth or sixth century. Around that time most of them were replaced as civil calendars by the Julian calendar, but with a year starting in September
September
to reflect the year of the indiction cycle. The Julian calendar
Julian calendar
spread beyond the borders of the Roman Empire through its use as the Christian liturgical calendar. When a people or a country was converted to Christianity, they generally also adopted the Christian calendar of the church responsible for conversion. Thus, Christian Nubia and Ethiopia
Ethiopia
adopted the Alexandrian calendar, while Christian Europe adopted the Julian calendar, in either the Catholic or Orthodox variant. Starting in the 16th century, European settlements in the Americas and elsewhere likewise inherited the Julian calendar
Julian calendar
of the mother country, until they adopted the Gregorian reform. The last country to adopt the Julian calendar
Julian calendar
was the Ottoman Empire, which used it for financial purposes for some time under the name Rumi calendar
Rumi calendar
and dropped the "escape years" which tied it to Muslim chronology in 1840. Leap year
Leap year
error Although the new calendar was much simpler than the pre-Julian calendar, the pontifices initially added a leap day every three years, instead of every four. There are accounts of this in Solinus,[45] Pliny,[46] Ammianus,[47] Suetonius,[48] and Censorinus.[49] Macrobius[50] gives the following account of the introduction of the Julian calendar: "Caesar’s regulation of the civil year to accord with his revised measurement was proclaimed publicly by edict, and the arrangement might have continued to stand had not the correction itself of the calendar led the priests to introduce a new error of their own; for they proceeded to insert the intercalary day, which represented the four quarter-days, at the beginning of each fourth year instead of at its end, although the intercalation ought to have been made at the end of each fourth year and before the beginning of the fifth. "This error continued for thirty-six years by which time twelve intercalary days had been inserted instead of the number actually due, namely nine. But when this error was at length recognised, it too was corrected, by an order of Augustus, that twelve years should be allowed to pass without an intercalary day, since the sequence of twelve such years would account for the three days which, in the course of thirty-six years, had been introduced by the premature actions of the priests." So, according to Macrobius,

the year was considered to begin after the Terminalia, (23 February)[51] the calendar was operated correctly from its introduction on 1 January 45 BC until the beginning of the fourth year (February 42 BC) at which point the priests inserted the first intercalation, Caesar's intention was to make the first intercalation at the beginning of the fifth year ( February
February
41 BC), the priests made a further eleven intercalations after 42 BC at three-year intervals so that the twelfth intercalation fell in 9 BC, had Caesar's intention been followed there would have been intercalations every four years after 41 BC, so that the ninth intercalation would have been in 9 BC, after 9 BC, there were twelve years without leap years, so that the leap days Caesar would have had in 5 BC, 1 BC and AD 4 were omitted and after AD 4 the calendar was operated as Caesar intended, so that the next leap year was AD 8 and then leap years followed every fourth year thereafter.[52]

Some people have had different ideas as to how the leap years went. The above scheme is that of Scaliger in the table below. He established that the Augustan reform was instituted in 8 BC. The table shows for each reconstruction the implied proleptic Julian date for the first day of Caesar's reformed calendar (Kal. Ian. AUC 709) and the first Julian date on which the Roman calendar
Roman calendar
date matches the Julian calendar
Julian calendar
after the completion of Augustus' reform. Alexander Jones claims that the correct Julian calendar
Julian calendar
was in use in Egypt in 24 BC,[41] implying that the first day of the reform in both Egypt and Rome, 1 January
January
45 BC, was the Julian date 1  January
January
if 45 BC was a leap year and 2  January
January
if it was not. This necessitates fourteen leap days up to and including AD 8 if 45 BC was a leap year and thirteen if it was not. Pierre Brind'Amour[53] argued that "only one day was intercalated between 1/1/45 and 1/1/40 (disregarding a momentary 'fiddling' in December
December
of 41[54] to avoid the nundinum falling on Kal. Ian."[55]

Scholar Date Triennial leap years (BC) First Julian day First aligned day Quadriennial leap year resumes

Bennett[56] 2003 44, 41, 38, 35, 32, 29, 26, 23, 20, 17, 14, 11, 8 31 Dec 46 BC 25 Feb 1 BC AD 4

Soltau[57] 1889 45, 41, 38, 35, 32, 29, 26, 23, 20, 17, 14, 11 2 Jan 45 BC 25 Feb AD 4 AD 8

Matzat[58] 1883 44, 41, 38, 35, 32, 29, 26, 23, 20, 17, 14, 11 1 Jan 45 BC 25 Feb 1 BC AD 4

Ideler[59] 1825 45, 42, 39, 36, 33, 30, 27, 24, 21, 18, 15, 12, 9 1 Jan 45 BC 25 Feb AD 4 AD 8

Kepler[60] 1614 43, 40, 37, 34, 31, 28, 25, 22, 19, 16, 13, 10 2 Jan 45 BC 25 Feb AD 4 AD 8

Harriot[61] After 1610 43, 40, 37, 34, 31, 28, 25, 22, 19, 16, 13, 10 1 Jan 45 BC 25 Feb 1 BC AD 4

Bünting[61] 1590 45, 42, 39, 36, 33, 30, 27, 24, 21, 18, 15, 12 1 Jan 45 BC 25 Feb 1 BC AD 4

Christmann[61][62] 1590 43, 40, 37, 34, 31, 28, 25, 22, 19, 16, 13, 10 2 Jan 45 BC 25 Feb AD 4 AD 7[61]

Scaliger[63] 1583 42, 39, 36, 33, 30, 27, 24, 21, 18, 15, 12, 9 2 Jan 45 BC 25 Feb AD 4 AD 8

In 1999, a papyrus was discovered which gives the dates of astronomical phenomena in 24 BC in both the Egyptian and Roman calendars. From 30 August
August
26 BC (Julian), Egypt had two calendars: the old Egyptian in which every year had 365 days and the new Alexandrian in which every fourth year had 366 days. Up to 28 August
August
22 BC (Julian) the date in both calendars was the same. The dates in the Alexandrian and Julian calendars are in one-to-one correspondence except for the period from 29 August
August
in the year preceding a Julian leap year to the following 24 February.[64] From a comparison of the astronomical data with the Egyptian and Roman dates, Alexander Jones[41] concluded that the Egyptian astronomers (as opposed to travellers from Rome) used the correct Julian calendar. An inscription has been discovered[65] which orders a new calendar to be used in Asia to replace the previous Greek lunar calendar. According to one translation[66] "Intercalation shall commence on the day after 14 Peritius [a.d. IX Kal. Feb, which would have been 15 Peritius] as it is currently constituted in the third year following promulgation of the decree. Xanthicus shall have 32 days in this intercalary year." This is historically correct. It was decreed by the proconsul that the first day of the year in the new calendar shall be Augustus' birthday, a.d. IX Kal. Oct. Every month begins on the ninth day before the kalends. The date of introduction, the day after 14 Peritius, was 1 Dystrus, the next month. The month after that was Xanthicus. Thus Xanthicus began on a.d. IX Kal. Mart., and normally contained 31 days. In leap year, however, it contained an extra "Sebaste day", the Roman leap day, and thus had 32 days. From the lunar nature of the old calendar we can fix the starting date of the new one as 24 January, a.d. IX Kal. Feb 5 BC in the Julian calendar, which was a leap year. Thus from inception the dates of the reformed Asian calendar are in one-to-one correspondence with the Julian. Another translation of this inscription[67] is "Intercalation shall commence on the day after the fourteenth day in the current month of Peritius [a.d. IX Kal. Feb], occurring every third year. Xanthicus shall have 32 days in this intercalary year." This would move the starting date back three years to 8 BC, and from the lunar synchronism back to 26 January
January
(Julian). But since the corresponding Roman date in the inscription is 24 January, this must be according to the incorrect calendar which in 8 BC Augustus
Augustus
had ordered to be corrected by the omission of leap days. As the authors of the previous paper point out, with the correct four-year cycle being used in Egypt and the three-year cycle abolished in Rome
Rome
it is unlikely that Augustus
Augustus
would have ordered the three-year cycle to be introduced in Asia. Month
Month
names The Julian reform did not immediately cause the names of any months to be changed. The old intercalary month was abolished and replaced with a single intercalary day at the same point (i.e., five days before the end of February). January
January
continued to be the first month of the year. The Romans later renamed months after Julius Caesar
Julius Caesar
and Augustus, renaming Quintilis
Quintilis
as "Iulius" (July)[8] in 44 BC and Sextilis
Sextilis
as "Augustus" (August) in 8 BC. Quintilis
Quintilis
was renamed to honour Caesar because it was the month of his birth.[68] According to a senatus consultum quoted by Macrobius, Sextilis
Sextilis
was renamed to honour Augustus
Augustus
because several of the most significant events in his rise to power, culminating in the fall of Alexandria, occurred in that month.[69] Other months were renamed by other emperors, but apparently none of the later changes survived their deaths. In AD 37, Caligula
Caligula
renamed September
September
as "Germanicus" after his father;[70] in AD 65, Nero
Nero
renamed April
April
as "Neroneus", May
May
as "Claudius" and June
June
as "Germanicus";[71] and in AD 84 Domitian
Domitian
renamed September
September
as "Germanicus" and October
October
as "Domitianus".[72] Commodus
Commodus
was unique in renaming all twelve months after his own adopted names ( January
January
to December): "Amazonius", "Invictus", "Felix", "Pius", "Lucius", "Aelius", "Aurelius", "Commodus", "Augustus", "Herculeus", "Romanus", and "Exsuperatorius".[73] The emperor Tacitus
Tacitus
is said to have ordered that September, the month of his birth and accession, be renamed after him, but the story is doubtful since he did not become emperor before November
November
275.[74] Similar honorific month names were implemented in many of the provincial calendars that were aligned to the Julian calendar.[75] Other name changes were proposed but were never implemented. Tiberius rejected a senatorial proposal to rename September
September
as "Tiberius" and October
October
as "Livius", after his mother Livia.[76] Antoninus Pius rejected a senatorial decree renaming September
September
as "Antoninus" and November
November
as "Faustina", after his empress.[77] Much more lasting than the ephemeral month names of the post-Augustan Roman emperors were the Old High German names introduced by Charlemagne. According to his biographer, Charlemagne
Charlemagne
renamed all of the months agriculturally into German.[78] These names were used until the 15th century, over 700 years after his rule, and continued, with some modifications, to see some use as "traditional" month names until the late 18th century. The names ( January
January
to December) were: Wintarmanoth ("winter month"), Hornung,[79] Lentzinmanoth ("spring month", " Lent
Lent
month"), Ostarmanoth (" Easter
Easter
month"), Wonnemanoth ("joy-month", a corruption of Winnimanoth "pasture-month"), Brachmanoth ("fallow-month"), Heuuimanoth ("hay month"), Aranmanoth ("reaping month"), Witumanoth ("wood month"), Windumemanoth ("vintage month"), Herbistmanoth ("harvest month"), and Heilagmanoth ("holy month"). The calendar month names used in western and northern Europe, in Byzantium, and by the Berbers, were derived from the Latin
Latin
names. However, in eastern Europe older seasonal month names continued to be used into the 19th century, and in some cases are still in use, in many languages, including: Belarusian, Bulgarian, Croatian, Czech, Finnish,[80] Georgian, Lithuanian, Macedonian, Polish, Romanian, Slovene, Ukrainian. When the Ottoman Empire
Ottoman Empire
adopted the Julian calendar, in the form of the Rumi calendar, the month names reflected Ottoman tradition. Year
Year
numbering The principal method used by the Romans to identify a year for dating purposes was to name it after the two consuls who took office in it, the eponymous period in question being the consular year. Beginning in 153 BC, consuls began to take office on 1 January, thus synchronizing the commencement of the consular and calendar years. The calendar year has begun in January
January
and ended in December
December
since about 450 BC according to Ovid
Ovid
or since about 713 BC according to Macrobius
Macrobius
and Plutarch
Plutarch
(see Roman calendar). Julius Caesar
Julius Caesar
did not change the beginning of either the consular year or the calendar year. In addition to consular years, the Romans sometimes used the regnal year of the emperor, and by the late 4th century documents were also being dated according to the 15-year cycle of the indiction. In 537, Justinian required that henceforth the date must include the name of the emperor and his regnal year, in addition to the indiction and the consul, while also allowing the use of local eras. In 309 and 310, and from time to time thereafter, no consuls were appointed.[81] When this happened, the consular date was given a count of years since the last consul (so-called "post-consular" dating). After 541, only the reigning emperor held the consulate, typically for only one year in his reign, and so post-consular dating became the norm. Similar post-consular dates were also known in the west in the early 6th century. The system of consular dating, long obsolete, was formally abolished in the law code of Leo VI, issued in 888. Only rarely did the Romans number the year from the founding of the city (of Rome), ab urbe condita (AUC). This method was used by Roman historians to determine the number of years from one event to another, not to date a year. Different historians had several different dates for the founding. The Fasti
Fasti
Capitolini, an inscription containing an official list of the consuls which was published by Augustus, used an epoch of 752 BC. The epoch used by Varro, 753 BC, has been adopted by modern historians. Indeed, Renaissance
Renaissance
editors often added it to the manuscripts that they published, giving the false impression that the Romans numbered their years. Most modern historians tacitly assume that it began on the day the consuls took office, and ancient documents such as the Fasti
Fasti
Capitolini which use other AUC systems do so in the same way. However, Censorinus, writing in the 3rd century AD, states that, in his time, the AUC year began with the Parilia, celebrated on 21 April, which was regarded as the actual anniversary of the foundation of Rome.[82] Many local eras, such as the Era of Actium and the Spanish Era, were adopted for the Julian calendar
Julian calendar
or its local equivalent in the provinces and cities of the Roman Empire. Some of these were used for a considerable time.[83] Perhaps the best known is the Era of Martyrs, sometimes also called Anno Diocletiani (after Diocletian), which was associated with the Alexandrian calendar
Alexandrian calendar
and often used by the Alexandrian Christians to number their Easters during the 4th and 5th centuries, and continues to be used by the Coptic and Ethiopian churches. In the eastern Mediterranean, the efforts of Christian chronographers such as Annianus of Alexandria
Alexandria
to date the Biblical creation of the world led to the introduction of Anno Mundi
Anno Mundi
eras based on this event.[84] The most important of these was the Etos Kosmou, used throughout the Byzantine world from the 10th century and in Russia until 1700. In the west, the kingdoms succeeding the empire initially used indictions and regnal years, alone or in combination. The chronicler Prosper of Aquitaine, in the fifth century, used an era dated from the Passion of Christ, but this era was not widely adopted. Dionysius Exiguus proposed the system of Anno Domini
Anno Domini
in 525. This era gradually spread through the western Christian world, once the system was adopted by Bede. The Julian calendar
Julian calendar
was also used in some Muslim countries. The Rumi calendar, the Julian calendar
Julian calendar
used in the later years of the Ottoman Empire, adopted an era derived from the lunar AH year equivalent to AD 1840, i.e., the effective Rumi epoch was AD 585. In recent years, some users of the Berber calendar
Berber calendar
have adopted an era starting in 950 BC, the approximate date that the Libyan pharaoh Sheshonq I came to power in Egypt. New Year's Day The Roman calendar
Roman calendar
began the year on 1 January, and this remained the start of the year after the Julian reform. However, even after local calendars were aligned to the Julian calendar, they started the new year on different dates. The Alexandrian calendar
Alexandrian calendar
in Egypt started on 29 August
August
(30 August
August
after an Alexandrian leap year). Several local provincial calendars were aligned to start on the birthday of Augustus, 23 September. The indiction caused the Byzantine year, which used the Julian calendar, to begin on 1 September; this date is still used in the Eastern Orthodox Church
Orthodox Church
for the beginning of the liturgical year. When the Julian calendar
Julian calendar
was adopted in AD 988 by Vladimir I of Kiev, the year was numbered Anno Mundi
Anno Mundi
6496, beginning on 1 March, six months after the start of the Byzantine Anno Mundi year with the same number. In 1492 (AM 7000), Ivan III, according to church tradition, realigned the start of the year to 1 September, so that AM 7000 only lasted for six months in Russia, from 1 March
March
to 31 August
August
1492.[85] During the Middle Ages
Middle Ages
1 January
January
retained the name New Year's Day
New Year's Day
(or an equivalent name) in all western European countries (affiliated with the Roman Catholic Church), since the medieval calendar continued to display the months from January
January
to December
December
(in twelve columns containing 28 to 31 days each), just as the Romans had. However, most of those countries began their numbered year on 25 December
December
(the Nativity of Jesus), 25 March
March
(the Incarnation of Jesus), or even Easter, as in France
France
(see the Liturgical year
Liturgical year
article for more details). In Anglo-Saxon England, the year most commonly began on 25 December, which, as (approximately) the winter solstice, had marked the start of the year in pagan times, though 25 March
March
(the equinox) is occasionally documented in the 11th century. Sometimes the start of the year was reckoned as 24 September, the start of the so-called "western indiction" introduced by Bede.[86] These practices changed after the Norman conquest. From 1087 to 1155 the English year began on 1 January, and from 1155 to 1751 began on 25 March.[87] In 1752 it was moved back to 1 January. (See Calendar
Calendar
(New Style) Act 1750). Even before 1752, 1 January
January
was sometimes treated as the start of the new year – for example by Pepys[88] – while the "year starting 25th March
March
was called the Civil or Legal Year".[89] To reduce misunderstandings on the date, it was not uncommon for a date between 1 January
January
and 24 March
March
to be written as "1661/62". This was to explain to the reader that the year was 1661 counting from March
March
and 1662 counting from January
January
as the start of the year.[90] (For more detail, see Dual dating). Most western European countries shifted the first day of their numbered year to 1 January
January
while they were still using the Julian calendar, before they adopted the Gregorian calendar, many during the 16th century. The following table shows the years in which various countries adopted 1 January
January
as the start of the year. Eastern European countries, with populations showing allegiance to the Orthodox Church, began the year on 1 September
September
from about 988. The Rumi calendar
Rumi calendar
used in the Ottoman Empire
Ottoman Empire
began the civil year on 1 March
March
until 1918.

Country Year
Year
starting 1 January[91][92] Adoption of new calendar

Republic of Venice 1522 1582

Holy Roman Empire[93] 1544 1582

Spain, Portugal 1556 1582

Prussia, Denmark–Norway 1559 1700

Sweden 1559 1753[94]

France 1567 1582

Southern Netherlands 1576[95] 1582

Lorraine 1579 1760

Holland, Zeeland 1583 1582

Dutch Republic
Dutch Republic
except Holland
Holland
and Zeeland 1583 1700

Scotland 1600 1752

Russia 1700 1918

Tuscany 1721 1750

British Empire
British Empire
excluding Scotland 1752 1752[96]

Serbia 1804[citation needed] 1918

Ottoman Empire
Ottoman Empire
(Turkey)[97] 1918 1917

From Julian to Gregorian Main article: Gregorian calendar The Julian calendar
Julian calendar
was in general use in Europe and northern Africa until 1582, when Pope Gregory XIII
Pope Gregory XIII
promulgated the Gregorian calendar. Reform was required because too many leap days are added with respect to the astronomical seasons on the Julian scheme. On average, the astronomical solstices and the equinoxes advance by about 11 minutes per year against the Julian year. As a result, the calculated date of Easter
Easter
gradually moved out of alignment with the March
March
equinox.

This is a visual example of the official date change from the Julian calendar to the Gregorian.

While Hipparchus
Hipparchus
and presumably Sosigenes were aware of the discrepancy, although not of its correct value,[98] it was evidently felt to be of little importance at the time of the Julian reform. However, it accumulated significantly over time: the Julian calendar gained a day about every 134 years. By 1582, it was ten days out of alignment from where it supposedly had been in 325 during the Council of Nicaea. The Gregorian calendar
Gregorian calendar
was soon adopted by most Catholic countries (e.g., Spain, Portugal, Poland, most of Italy). Protestant countries followed later, and some countries of eastern Europe even later. In the British Empire
British Empire
(including the American colonies), Wednesday 2 September
September
1752 was followed by Thursday 14 September
September
1752. For 12 years from 1700 Sweden
Sweden
used a modified Julian calendar, and adopted the Gregorian calendar
Gregorian calendar
in 1753. Since the Julian and Gregorian calendars were long used simultaneously, although in different places, calendar dates in the transition period are often ambiguous, unless it is specified which calendar was being used. In some circumstances, double dates might be used, one in each calendar. The notation "Old Style" (O.S.) is sometimes used to indicate a date in the Julian calendar, as opposed to "New Style" (N.S.), which either represents the Julian date with the start of the year as 1 January
January
or a full mapping onto the Gregorian calendar. This notation is used to clarify dates from countries which continued to use the Julian calendar
Julian calendar
after the Gregorian reform, such as Great Britain, which did not switch to the reformed calendar until 1752, or Russia, which did not switch until 1918. This is why the Russian Revolution of 7 November
November
1917 N.S. is known as the October
October
Revolution, because it began on 25 October
October
OS. Throughout the long transition period, the Julian calendar
Julian calendar
has continued to diverge from the Gregorian. This has happened in whole-day steps, as leap days which were dropped in certain centennial years in the Gregorian calendar
Gregorian calendar
continued to be present in the Julian calendar. Thus, in the year 1700 the difference increased to 11 days; in 1800, 12; and in 1900, 13. Since 2000 was a leap year according to both the Julian and Gregorian calendars, the difference of 13 days did not change in that year: 29 February
February
2000 (Gregorian) fell on 16 February
February
2000 (Julian). This difference will persist until the last day of February
February
2100 (Gregorian), since 2100 is not a Gregorian leap year, but is a Julian leap year. Monday 1 March
March
2100 (Gregorian) falls on Monday 16 February
February
2100 (Julian).[99] Eastern Orthodox usage

Russian icon
Russian icon
of the Theophany (the baptism of Jesus
Jesus
by John the Baptist) (6 January), the highest-ranked feast which occurs on the fixed cycle of the Eastern Orthodox liturgical calendar.

Although most Eastern Orthodox countries (most of them in eastern or southeastern Europe) had adopted the Gregorian calendar
Gregorian calendar
by 1924, their national churches had not. The "Revised Julian calendar" was endorsed by a synod in Constantinople
Constantinople
in May
May
1923, consisting of a solar part which was and will be identical to the Gregorian calendar
Gregorian calendar
until the year 2800, and a lunar part which calculated Easter
Easter
astronomically at Jerusalem. All Orthodox churches refused to accept the lunar part, so almost all Orthodox churches continue to celebrate Easter
Easter
according to the Julian calendar
Julian calendar
(with the exception of the Estonian Orthodox Church and the Finnish Orthodox Church).[100][101] The solar part of the Revised Julian calendar
Revised Julian calendar
was accepted by only some Orthodox churches. Those that did accept it, with hope for improved dialogue and negotiations with the western denominations, were the Ecumenical Patriarchate of Constantinople, the Patriarchates of Alexandria, Antioch, the Orthodox Churches of Greece, Cyprus, Romania, Poland (from 1924 to 2014; it is still permitted to use the Revised Julian calendar
Revised Julian calendar
in parishes that want it), Bulgaria (the last in 1963), and the Orthodox Church
Orthodox Church
in America (although some OCA parishes are permitted to use the Julian calendar). Thus these churches celebrate the Nativity on the same day that western Christians do, 25 December
December
Gregorian until 2799. The Orthodox Churches of Jerusalem, Russia, Serbia, Montenegro, Poland (from 15 June
June
2014), Macedonia, Georgia, Ukraine, and the Greek Old Calendarists and other groups continue to use the Julian calendar, thus they celebrate the Nativity on 25 December
December
Julian (which is 7 January
January
Gregorian until 2100). The Russian Orthodox Church
Orthodox Church
has some parishes in the west which celebrate the Nativity on 25 December Gregorian until 2799. Parishes of the Orthodox Church
Orthodox Church
in America Bulgarian Diocese, both before and after the 1976 transfer of that diocese from the Russian Orthodox Church
Orthodox Church
Outside Russia
Russia
to the Orthodox Church
Orthodox Church
in America, were permitted to use this date. Some Old Calendarist
Old Calendarist
groups which stand in opposition to the state churches of their homelands will use the Great Feast of the Theophany (6 January
January
Julian/19 January
January
Gregorian) as a day for religious processions and the Great Blessing of Waters, to publicise their cause.[citation needed] The Oriental Orthodox
Oriental Orthodox
Churches generally use the local calendar of their homelands. However, when calculating the Nativity Feast, most observe the Julian calendar. This was traditionally for the sake of unity throughout Christendom. In the west, some Oriental Orthodox Churches either use the Gregorian calendar
Gregorian calendar
or are permitted to observe the Nativity according to it. The Armenian Apostolic Orthodox Church celebrates the Nativity as part of the Feast of Theophany according to its traditional calendar.[citation needed] See also

Byzantine calendar Conversion between Julian and Gregorian calendars Julian day Julian year (astronomy) List of adoption dates of the Gregorian calendar
Gregorian calendar
per country Mixed-style date Proleptic Gregorian calendar Proleptic Julian calendar Revised Julian calendar Roman timekeeping Week

Notes

^ Richards 2013, p. 595. ^ Using value from Richards (2013, p. 587) for tropical year in mean solar days, the calculation is 1/(365.2425-365.24217) ^ Introduction to Calendars. (15 May
May
2013). United States
United States
Naval Observatory. ^ Social Security Administration publication GN 00307.180 – Gregorian/Julian calendar. ^ Social Security Administration (26 August
August
2005). "GN 00307.180 Gregorian/Julian calendar". Retrieved 27 July
July
2016. Although the Russian authorities officially changed calendars in 1918, individual registrars particularly in remote areas continued to use the old calendar for as long as ten years.  ^ Towards a Common Date of Easter. (5–10 March). World Council of Churches/Middle East Council of Churches Consultation, Aleppo, Syria. ^ Oxby, Clare (1998). "The manipulation of time: Calendars and power in the Sahara". Nomadic Peoples, New Series. 2 (1/2): 137–149. JSTOR 43123542.  ^ a b c The letter J was not invented until the 16th century. ^ The spelling Quinctilis is also attested; see page 669 of The Oxford Companion to the Year. ^ T H Key, "A Dictionary of Greek and Roman Antiquities" (article Calendarium), London, 1875, available at [1]. ^ Blackburn, B & Holford-Strevens, L The Oxford Companion to the Year, Oxford University Press, 1999, reprinted with corrections, 2003, pp. 669–70. ^ Censorinus, De die natali 20.7 (Latin) ^ a b Varro, On Agriculture I.1.28. ^ Pliny, Natural History: (Book 18, LIX / LXVI / LXVIII / LXXIV). ^ Parker, R. A. ( May
May
1974). "Ancient Egyptian Astronomy". Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences. 276 (1257): 51–65. JSTOR 74274.  ^ Hartner, Willy. "The young Avestan and Babylonian calendars and the antecedents of precession." Journal for the History
History
of Astronomy
Astronomy
10 (1979): 1. pp. 1–22. doi:10.1177/002182867901000102 ^ Stern, Sacha. Calendars in antiquity: Empires, states, and societies. Oxford University Press, 2012., p. 178. ^ a b Lucan, Pharsalia: Book 10. ^ Émile Biémont, Rythmes du temps, astronomie et calendriers, éd. De Boeck (Bruxelles), 2000 (ISBN 2-8041-3287-0), p. 224. ^ Suetonius, Caesar 52.1. ^ Plutarch, Lives of the Noble Grecians and Romans: Caesar 59. ^ Pliny, Natural History: (Book 18, LVII). ^ Encyclopædia Britannica Sosigenes of Alexandria. ^ Macrobius, Saturnalia I.14.2 (Latin). ^ It is not known why he decided that 67 was the correct number of days to add, nor whether he intended to align the calendar to a specific astronomical event such as the winter solstice. Ideler suggested (Handbuch der mathematischen und technischen Chronologie II 123–125) that he intended to align the winter solstice to a supposedly traditional date of 25 December. The number may compensate for three omitted intercalary months (67 = 22+23+22). It also made the distance from 1 March
March
46 BC, the original New Years Day
Day
in the Roman calendar, to 1 January
January
45 BC 365 days. ^ e.g., "... we have a sidelight on what was involved in "the year of confusion" as it was called. According to Dion Cassius, the historian, there was a governor in Gaul who insisted that, in the lengthened year, two months' extra taxes should be paid. The extra months were called Undecimber and Duodecimber." (P. W. Wilson, The romance of the calendar (New York, 1937), 112). The eponymous dating of the cited passage (Dio Cassius 54.21) shows that it actually refers to an event of 15 BC, not 46 BC. ^ J. Rüpke, The Roman Calendar
Calendar
from Numa to Constantine: Time, History
History
and the Fasti, 117f., suggests, based on the ritual structures of the calendar, that 5 days were added to November
November
and that the two intercalary months each had 31 days, with Nones and Ides on the 7th and 15th. ^ William Smith, Dictionary of Greek and Roman Antiquities: Year
Year
of Julius Caesar), following Ideler, interprets Macrobius, Saturnalia 1.14.13 (Latin) to mean that Caesar decreed that the first day of the new calendar began with the new moon which fell on the night of 1/2 January
January
45 BC. (The new moon was on 2 January
January
45 BC (in the Proleptic Julian calendar) at 00:21 UTC, according to IMCCE (a branch of the Paris Observatory): Phases of the moon (between −4000 and +2500) Archived 2011-07-20 at the Wayback Machine..) However, more recent studies of the manuscripts have shown that the word on which this is based, which was formerly read as lunam, should be read as linam, meaning that Macrobius
Macrobius
was simply stating that Caesar published an edict giving the revised calendar – see e.g., p.99 in the translation of Macrobius
Macrobius
by P. Davies. Smith gives no source or justification for his other speculation that Caesar originally intended to commence the year precisely with the winter solstice. ^ Macrobius, Saturnalia 1.14.9 (Latin). Exceptionally, the extra day in April
April
was inserted as the 26th, a.d. VI Kal. Mai. in the Julian calendar, in order to avoid adding a day to the Floralia, which ran from a.d. IV Kal. Mai. (27 April
April
in the pre-Julian calendar) to a.d. V Non. Mai. ^ Macrobius, Saturnalia 1.14.12 (Latin). ^ A. K. Michels, The Calendar
Calendar
of the Roman Republic
Roman Republic
Appendix II; J. Rüpke, The Roman Calendar
Calendar
from Numa to Constantine 113–114, 126–132, 147. ^ W. Sternkopf, "Das Bissextum", (JCP 41 (1895) 718–733). ^ Justinian, Digest 50.16.98. ^ "The statute De anno et die bissextili, made at Westminster, Anno 21 Hen. III. and Anno Dom. 1236". The Statutes at Large from Magna Charta to the End of the Reign of King Henry the Sixth. 1. London. 1763.  ^ Dio Cassius 48.33.4, 60.24.7; C. J. Bennett, "The Imperial Nundinal Cycle", Zeitschrift für Papyrologie und Epigraphik 147 (2004) 175–179. ^ Roscoe Lamont, "The Roman calendar
Roman calendar
and its reformation by Julius Caesar", Popular Astronomy
Astronomy
27 (1919) 583–595. Sacrobosco's theory is discussed on pages 585–587. ^ Roman Republican calendar. ^ Macrobius, Saturnalia 1.13.7 and 1.14.7–8 (Latin), Censorinus, De die natali 20.10 (Latin), (English). ^ Censorinus, De die natali 20.9 (Latin), (English) ^ Macrobius, Saturnalia 1.14.7 (Latin) ^ a b c Alexander Jones, Calendrica II: Date Equations from the Reign of Augustus, Zeitschrift fűr Papyrologie und Epigraphik 129 (2000) 159–166, available at [2]. ^ A. Degrassi, Inscriptiones Italiae XIII: Fasti
Fasti
et Elogia 2: Fasti Anni Numani et Iuliani; Accedunt Feralia, Menologia Rustica, Parapegmata (Rome, 1963) 66 (Latin) ^ This section is based on S. Stern, Calendars in Antiquity (OUP 2012) pp. 259–297. ^ Studied in detail in W. Kubitschek, Die Kalendarbücher von Florenz, Rom und Leyden (Vienna, 1915). ^ Gaius Julius Solinus, De mirabilibus mundi, c.3, available at [3]. ^ Gaius Plinius Secundus, Natural History, Vol. 2, 18.57, tr. J Bostock and H T Riley, London 1855, available at [4][permanent dead link]. ^ The Roman History
History
of Ammianus Marcellinus, 26.10, Loeb Classical Library vol. II, Harvard 1940, available at [5]. ^ Gaius Suetonius
Suetonius
Tranquillus, Life of Julius Caesar, 40.1, Loeb Classical Library, Harvard 1913, available at [6]. ^ Censorinus, The Natal Day, 20.30, tr. William Maude, New York 1900 available at [7]. ^ Macrobius
Macrobius
Ambrosius Theodosius, Saturnalia, 1.14.13–1.14.14, tr. Percival Vaughan Davies, New York 1969, Latin
Latin
text at [8] ^ Marcus Terentius Varro, On the Latin
Latin
Language, 6.13, tr. Roland Kent, London 1938 available at [9]. ^ Nautical Almanac Offices of the United Kingdom and the United States. (1961). Explanatory Supplement to the Astronomical Ephemeris and the American Ephemeris
Ephemeris
and Nautical Almanac, London: Her Majesty's Stationery Office. p. 410–11. ^ Pierre Brind'Amour, Le calendrier romain, Ottawa 1983, pp. 45–46. ^ Dio Cassius 48.33.4, tr. Earnest Cary, Loeb Classical Library, 9 vol., Harvard 1914–1927, available at [10]. ^ Refutation of Brind'Amour's theory by John Ward, Re: Intercalation in 45BC to 8AD, East Carolina University Calendar
Calendar
discussion List CALNDR-L, April
April
1998. ^ C. J. Bennett, "The Early Augustan Calendars in Rome
Rome
and Egypt", Zeitschrift fűr Papyrologie und Epigraphik 142 (2003) 221–240 and "The Early Augustan Calendars in Rome
Rome
and Egypt: Addenda et Corrigenda", Zeitschrift fűr Papyrologie und Epigraphik 147 (2004) 165–168; see also Chris Bennett, A.U.C. 730 = 24 B.C. (Egyptian papyrus). ^ W. Soltau, Römische Chronologie (Freiburg, 1889) 170–173. He accepted Matzat's phase of the triennial cycle but argued that it was absurd to suppose that Caesar would have made the second Julian year a leap year and that the 36 years had to be accounted from 45 BC. ^ H. Matzat, Römische Chronologie I (Berlin, 1883), 13–18. His argument rested on Dio Cassius 48.33.4 which mentions a leap day inserted in 41 BC, "contrary to the (i.e., Caesar's) rule", in order to avoid having a market day on the first day of 40 BC. Dio stated that this leap day was compensated for "later". Matzat proposed this was done by omitting a scheduled leap day in 40 BC, rather than by omitting a day from an ordinary year. ^ C. L. Ideler, Handbuch der mathematischen und technischen Chronologie (Berlin, 1825) II 130–131. He argued that Caesar would have enforced the bissextile day by introducing it in his first reformed year. T. E. Mommsen, Die Römische Chronologie bis auf Caesar (Berlin, 1859) 282–299, provided additional circumstantial arguments. ^ J. Kepler, De Vero Anno Quo Æternus Dei Filius Humanan Naturam in Utero Benedictæ Virginis Mariæ Assumpsit (Frankfurt, 1614) Cap. V, repub. in F. Hammer (ed.), Johannes Keplers Gesammelte Werke (Berlin, 1938) V 28. ^ a b c d For the list of triennial leap years proposed by Bünting, Christmann and Harriot, see Harriot's comparative table reproduced by Simon Cassidy (Fig. 6). The table numbers years as Julian years, where Julian year 1 = 45 BC. Thus, Scaliger and Clavius (col. 7) resume intercalation in Julian year 53 = AD 8, while Bünting (col. 8) and Harriot (col. 3) resume it in Julian year 49 = AD 4 and Christmann (col. 9) in year 52 = AD 7. ^ J. Christmann Muhamedis Alfragani arabis chronologica et astronomica elementa (Frankfurt, 1590), 173. His argument assumed that the triennial cycle started in the third Julian year. ^ J. J. Scaliger, De emendatione temporum (Paris, 1583), 159, 238. ^ Dieter Hagedorn, Zum aegyptischen Kalender unter Augustus, Zeitschrift fűr Papyrologie und Epigraphik 100 (1994) 211–222, available at [11]. ^ OGIS 458 (Greek). ^ B A Buxton and R Hannah in Studies in Latin
Latin
Literature and Roman History
History
(ed. C Deroux), XII 290. ^ U. Laffi, "Le iscrizioni relative all'introduzione nel 9 a.c. del nuovo calendario della provincia d'Asia", Studi Classici e Orientali 16 (1967) 5–99. ^ Suetonius, Caesar 76.1. ^ Suetonius, Augustus
Augustus
31.2; Macrobius, Saturnalia 1.12.35 (Latin) ^ Suetonius, Caligula
Caligula
15.2. ^ Tacitus, Annals 15.74, 16.12. ^ Suetonius, Domitian
Domitian
13.3. ^ Dio Cassius 73.15.3. ^ Historia Augusta, Tacitus
Tacitus
13.6. On the chronology see R. McMahon, Tacitus. ^ Surveyed in K. Scott, Honorific Months, Yale Classical Studies 2 (1931) 201–278. ^ Suetonius, Tiberius
Tiberius
26.2. ^ Historia Augusta, Antoninus Pius
Antoninus Pius
10.1. ^ Einhard, Life of Charlemagne, 29. ^ This name of February, the only name in the list without the "month" suffix, is explained by König, Festschrift Bergmann (1997), pp. 425 ff. as a collective of horn, taken to refer to the antlers shed by red deer during this time. Older explanations compare the name with Old Frisian horning (Anglo-Saxon hornung-sunu, Old Norse hornungr) meaning "bastard, illegitimate son", taken to imply a meaning of "disinherited" in reference to February
February
being the shortest of months. ^ "Calendar, Finnish". English-Word Information.  ^ Chronography of AD 354. ^ Censorinus De die natali 21.6 (Latin). Because the festivities associated with the Parilia
Parilia
conflicted with the solemnity of Lent, which was observed until the Saturday before Easter
Easter
Sunday, the early Roman church did not celebrate Easter
Easter
after 21 April
April
– Charles W. Jones, "Development of the Latin
Latin
Ecclesiastical calendar", Bedae Opera de Temporibus (1943), 1–122, p.28. ^ For a partial survey see A. E. Samuel, Greek and Roman Chronology: calendars and years in classical antiquity (Munich, 1972), 245ff. Samuel introduces his survey by saying: "The number of eras which came into use and then expired to be replaced by yet other eras during Hellenistic and Roman times is probably not infinite, but I have not been able to find the end of them." Anatolian eras are exhaustively surveyed in W. Leschhorn, Antike Ären: Zeitrechnung, Politik und Geschichte im Schwarzmeerraum und in Kleinasien nördlich des Tauros (Stuttgart, 1993). ^ A. A. Mosshammer, The Easter
Easter
Computus
Computus
and the Origins of the Christian Era (Oxford, 2008) 27–29. ^ История календаря в России и в СССР ( Calendar
Calendar
history in Russia
Russia
and in the USSR). ^ M. L. R. Beaven, "The Regnal Dates of Alfred, Edward the Elder, and Athelstan", English Historical Review 32 (1917) 517–531; idem, "The Beginning of the Year
Year
in the Alfredian Chronicle (866–87)", English Historical Review 33 (1918) 328–342. ^ Catholic Encyclopedia, General Chronology
Chronology
(Beginning of the Year). ^ Pepys Diary, "I sat down to end my journell for this year, ..." ^ Spathaky, Mike Old Style and New Style dates
Old Style and New Style dates
and the change to the Gregorian calendar. ^ Spathaky, Mike Old Style and New Style dates
Old Style and New Style dates
and the change to the Gregorian calendar. "An oblique stroke is by far the most usual indicator, but sometimes the alternative final figures of the year are written above and below a horizontal line, as in a fraction (a form which cannot easily be reproduced here in ASCII text). Very occasionally a hyphen is used, as 1733-34." ^ John James Bond, "Commencement of the Year", Handy-book of rules and tables for verifying dates with the Christian era, (London: 1875), 91–101. ^ Mike Spathaky Old Style and New Style Dates and the change to the Gregorian Calendar: A summary for genealogists. ^ The source has Germany, whose current area during the sixteenth century was a major part of the Holy Roman Empire, a religiously divided confederation. The source is unclear as to whether all or only parts of the country made the change. In general, Roman Catholic countries made the change a few decades before Protestant countries did. ^ Sweden's conversion is complicated and took much of the first half of the 18th century. See Swedish calendar. ^ Per decree of 16 June
June
1575. Hermann Grotefend, "Osteranfang" (Easter beginning), Zeitrechnung de Deutschen Mittelalters und der Neuzeit ( Chronology
Chronology
of the German Middle Ages
Middle Ages
and modern times) (1891–1898). ^ 1751 in England only lasted from 25 March
March
to 31 December. The dates 1 January
January
to 24 March
March
which would have concluded 1751 under the old calendar became part of 1752 when the beginning of the numbered year was changed from 25 March
March
to 1 January. ^ See Rumi calendar
Rumi calendar
for details. It is often stated that Turkey adopted the Gregorian calendar
Gregorian calendar
in 1926 or 1927. This refers to the adoption of the Anno domini era. ^ Richards 1998, p. 216. ^ Walker 2009. ^ "Estonian Orthodox Church
Orthodox Church
(Estonian Events)". Vancouveri Eesti Apostliku Õigeusu Kirik. 2010.  ^ Bishop Photius of Triaditsa, "The 70th Anniversary of the Pan-Orthodox Congress, Part II of II"; "HELSINGIN SANOMAT (International edition)". 21 September
September
2007. 

Bibliography

Bonnie Blackburn and Leofranc Holford-Strevens, The Oxford Companion to the Year, Oxford University Press, reprinted with corrections 2003. Brind'Amour, Pierre (1983). Le Calendrier romain: Recherches chronologiques. Ottawa University Press.  "Ethiopian Time". Washington D.C.: Embassy of Ethiopia. 2008.  Feeney, Dennis (2007). Caesar's Calendar: Ancient Time
Time
and the Beginnings of History. Berkeley: University of California Press.  Rüpke, Jörg (2011). The Roman Calendar
Calendar
from Numa to Constantine: Time, History
History
and the Fasti. Wiley.  Nautical Almanac Offices of the United Kingdom and the United States of America (1961). Explanatory Supplement to the Astronomical Ephemeris
Ephemeris
and the American Ephemeris
Ephemeris
and Nautical Almanac. London: Her Majesty's Stationery Office.  Richards, E. G (1998). Mapping time: the calendar and its history. Oxford University Press. ISBN 978-0-19-286205-1.  Richards, E. G. (2013). Urban, Sean E.; Seidelmann, P. Kenneth, eds. Explanatory Supplement to the Astronomical Almanac (3rd ed.). Mill Valley, Calif: University Science Books. ISBN 978-1-891389-85-6.  Stern, Sacha (2012). Calendars in Antiquity: Empires, States and Societies. Oxford University Press.  Walker, John (2009). " Calendar
Calendar
Converter". 

External links

Look up evenly divisible in Wiktionary, the free dictionary.

Wikimedia Commons has media related to Julian calendar.

Calendars through the ages on WebExhibits. Calendar
Calendar
FAQ Roman Dates The Roman Calendar Calendar
Calendar
Converter – converts between several calendars, for example Gregorian, Julian, Mayan, Persian, Hebrew

v t e

Calendars

Systems

Lunar Lunisolar Solar

In wide use

Astronomical Bengali Chinese Ethiopian Gregorian Hebrew Hindu Iranian Islamic ISO Unix time

In more limited use

Akan Armenian Assyrian Bahá'í (Badí‘) Balinese pawukon Balinese saka Berber Buddhist Burmese Chinese Coptic Gaelic Germanic Heathen Georgian Hebrew Hindu or Indian

Vikram Samvat Saka

Igbo Iranian

Jalali (medieval) Hijri (modern) Zoroastrian

Islamic

Fasli Tabular

Jain Japanese Javanese Korean

Juche

Kurdish Lithuanian Malayalam Mongolian Melanau Nanakshahi Nepal Sambat Nisg̱a'a Oromo Romanian Somali Sesotho Slavic

Slavic Native Faith

Tamil Thai

lunar solar

Tibetan Vietnamese Xhosa Yoruba

Types

Runic Mesoamerican

Long Count Calendar
Calendar
round

Christian variants

Julian

Revised

Liturgical year

Eastern Orthodox

Saints

Historical

Attic Aztec

Tonalpohualli Xiuhpohualli

Babylonian Bulgar Byzantine Celtic Cham Culāsakaraj Egyptian Florentine French Republican Germanic Greek Hindu Inca Macedonian Maya

Haab' Tzolk'in

Muisca Pentecontad Pisan Rapa Nui Roman calendar Rumi Soviet Swedish Turkmen

By specialty

Holocene (anthropological) Proleptic Gregorian / Proleptic Julian (historiographical) Darian (Martian) Dreamspell
Dreamspell
(New Age) Discordian / Pataphysical (surreal)

Proposals

Calendar
Calendar
reform Hanke–Henry Permanent International Fixed Pax Positivist Symmetry454 Tranquility World

New Earth Time

Fictional

Discworld Greyhawk Middle-earth Stardate Star Wars (Galactic Standard Calendar)

Displays and applications

Electronic Perpetual Wall

Year
Year
naming and numbering

Terminology

Era Epoch Regnal name Regnal year Year
Year
zero

Systems

Ab urbe condita Anno Domini/Common Era Anno Mundi Assyrian Before Present Chinese Imperial Chinese Minguo Human Era Japanese Korean Seleucid Spanish Yugas

Satya Treta Dvapara Kali

Vietnamese

List of calendars

v t e

Ancient Rome
Ancient Rome
topics

Outline Timeline

Epochs

Foundation Kingdom

overthrow

Republic

Empire

Pax Romana Principate Dominate Western Empire

fall historiography of the fall

Byzantine Empire

decline fall

Constitution

History Kingdom Republic Empire Late Empire Senate Legislative assemblies

Curiate Centuriate Tribal Plebeian

Executive magistrates SPQR

Government

Curia Forum Cursus honorum Collegiality Emperor Legatus Dux Officium Prefect Vicarius Vigintisexviri Lictor Magister militum Imperator Princeps senatus Pontifex Maximus Augustus Caesar Tetrarch Optimates Populares Province

Magistrates

Ordinary

Consul Censor Praetor Tribune Tribune
Tribune
of the Plebs Military tribune Quaestor Aedile Promagistrate Governor

Extraordinary

Rex Interrex Dictator Magister Equitum Decemviri Consular Tribune Triumvir

Law

Twelve Tables Mos maiorum Citizenship Auctoritas Imperium Status Litigation

Military

Borders Establishment Structure Campaigns Political control Strategy Engineering Frontiers and fortifications

castra

Technology Army

Legion Infantry tactics Personal equipment Siege engines

Navy Auxiliaries Decorations and punishments Hippika gymnasia

Economy

Agriculture Deforestation Commerce Finance Currency Republican currency Imperial currency

Technology

Abacus Numerals Civil engineering Military engineering Military technology Aqueducts Bridges Circus Concrete Domes Forum Metallurgy Roads Sanitation Thermae

Culture

Architecture Art Bathing Calendar Clothing Cosmetics Cuisine Hairstyles Education Literature Music Mythology Religion Romanization Sexuality Theatre Wine

Society

Patricians Plebs Conflict of the Orders Secessio plebis Equites Gens Tribes Naming conventions Demography Women Marriage Adoption Slavery Bagaudae

Latin

History Alphabet Versions

Old Classical Vulgar Late Medieval Renaissance New Contemporary Ecclesiastical

Romance languages

Writers

Latin

Ammianus Marcellinus Appian Appuleius Asconius Pedianus Augustine Aurelius Victor Ausonius Boëthius Caesar Catullus Cassiodorus Censorinus Cicero Claudian Columella Ennius Eutropius Fabius Pictor Festus Florus Frontinus Fulgentius Gellius Horace Jerome Juvenal Livy Lucan Lucretius Macrobius Marcus Aurelius Martial Orosius Ovid Petronius Phaedrus Plautus Pliny the Elder Pliny the Younger Priscian Propertius Quintilian Quintus Curtius Rufus Sallust Seneca the Elder Seneca the Younger Servius Sidonius Apollinaris Statius Suetonius Symmachus Tacitus Terence Tertullian Tibullus Valerius Antias Valerius Maximus Varro Velleius Paterculus Verrius Flaccus Virgil Vitruvius

Greek

Arrian Cassius Dio Diodorus Siculus Dionysius of Halicarnassus Dioscorides Eusebius of Caesaria Galen Herodian Josephus Pausanias Philostratus Phlegon of Tralles Photius Plutarch Polybius Porphyrius Procopius Strabo Zonaras Zosimus

Major cities

Alexandria Antioch Aquileia Berytus Bononia Carthage Constantinopolis Eboracum Leptis Magna Londinium Lutetia Mediolanum Pompeii Ravenna Roma Smyrna Vindobona Volubilis

Lists and other topics

Cities and towns Climate Consuls Distinguished women Emperors Generals Gentes Geographers Institutions Laws Legacy Legions Nomina Tribunes Wars and battles

Fiction Films

v t e

Time

Key concepts

Past

history deep time

Present Future Futures studies Far future in religion Far future in science fiction and popular culture Timeline
Timeline
of the far future Eternity Eternity
Eternity
of the world

Measurement and standards

Chronometry

UTC UT TAI Unit of time Planck time Second Minute Hour Day Week Month Season Year Decade Century Millennium Tropical year Sidereal year Samvatsara

Measurement systems

Time
Time
zone Six-hour clock 12-hour clock 24-hour clock Daylight saving time Solar time Sidereal time Metric time Decimal time Hexadecimal time

Calendars

Gregorian Julian Hebrew Islamic Lunar Solar Hijri Mayan Intercalation Leap second Leap year

Clocks

Horology History
History
of timekeeping devices Main types

astrarium atomic

quantum

marine sundial sundial markup schema watch water-based

Chronology History

Astronomical chronology Big History Calendar
Calendar
era Chronicle Deep time Periodization Regnal year Timeline

Religion Mythology

Dreamtime Kāla Kalachakra Prophecy Time
Time
and fate deities Wheel of time Immortality

Philosophy of time

A-series and B-series B-theory of time Causality Duration Endurantism Eternal return Eternalism Event Multiple time dimensions Perdurantism Presentism Static interpretation of time Temporal finitism Temporal parts The Unreality of Time

Human experience and use of time

Accounting period Chronemics Fiscal year Generation time Mental chronometry Music Procrastination Punctuality Temporal database Term Time
Time
discipline Time
Time
management Time
Time
perception

Specious present

Time-tracking software Time-use research Time-based currency
Time-based currency
(time banking) Time
Time
value of money Time
Time
clock Timesheet Yesterday – Today – Tomorrow

Time
Time
in

Geology

Geological time

age chron eon epoch era period

Geochronology Geological history of Earth

Physics

Absolute time and space Arrow of time Chronon Coordinate time Imaginary time Planck epoch Planck time Proper time Rate Spacetime Theory of relativity Time
Time
dilation

gravitational

Time
Time
domain Time
Time
translation symmetry Time
Time
reversal symmetry

other subject areas

Chronological dating Chronobiology Circadian rhythms Dating methodologies in archaeology Time
Time
geography

Related topics

Carpe diem Clock
Clock
position Space System time Tempus fugit Time
Time
capsule Time
Time
complexity Time
Time
signature Time
Time
travel

Time
Time
portal Category

v t e

Time
Time
measurement and standards

Chronometry Orders of magnitude Metrology

International standards

Coordinated Universal Time

offset

UT ΔT DUT1 International Earth Rotation and Reference Systems Service ISO 31-1 ISO 8601 International Atomic Time 6-hour clock 12-hour clock 24-hour clock Barycentric Coordinate Time Barycentric Dynamical Time Civil time Daylight saving time Geocentric Coordinate Time International Date Line Leap second Solar time Terrestrial Time Time
Time
zone 180th meridian

Obsolete standards

Ephemeris
Ephemeris
time Greenwich Mean Time Prime meridian

Time
Time
in physics

Absolute time and space Spacetime Chronon Continuous signal Coordinate time Cosmological decade Discrete time and continuous time Planck time Proper time Theory of relativity Time
Time
dilation Gravitational time dilation Time
Time
domain Time
Time
translation symmetry T-symmetry

Horology

Clock Astrarium Atomic clock Complication History
History
of timekeeping devices Hourglass Marine chronometer Marine sandglass Radio clock Watch Water clock Sundial Dialing scales Equation of time History
History
of sundials Sundial
Sundial
markup schema

Calendar

Astronomical Dominical letter Epact Equinox Gregorian Hebrew Hindu Intercalation Islamic Julian Leap year Lunar Lunisolar Solar Solstice Tropical year Weekday determination Weekday names

Archaeology
Archaeology
and geology

Chronological dating Geologic time scale International Commission on Stratigraphy

Astronomical chronology

Galactic year Nuclear timescale Precession Sidereal time

Other units of time

Flick Shake Jiffy Second Minute Moment Hour Day Week Fortnight Month Year Olympiad Lustrum Decade Century Saeculum Millennium

Related topics

Chronology Duration

music

Mental chronometry Metric time System time Time
Time
value of money Timekeeper

v t e

Chronology

Key topics

Archaeology Astronomy Geology History Paleontology Time

Eras Epochs

Calendar
Calendar
eras

Human Era Ab urbe condita Anno Domini / Common Era Anno Mundi Byzantine era Seleucid era Spanish era Before Present Hijri Egyptian Sothic cycle Hindu units of time
Hindu units of time
(Yuga) Mesoamerican

Long Count Short Count Tzolk'in Haab'

Regnal year

Canon of Kings Lists of kings Limmu

Era names

Chinese Japanese Korean Vietnamese

Calendars

Pre-Julian / Julian

Pre-Julian Roman Original Julian Proleptic Julian Revised Julian

Gregorian

Gregorian Proleptic Gregorian Old Style and New Style dates Adoption of the Gregorian calendar Dual dating

Astronomical

Lunisolar Solar Lunar Astronomical year numbering

Others

Chinese sexagenary cycle Geologic Calendar Hebrew Iranian Islamic ISO week date Mesoamerican

Maya Aztec

Winter count
Winter count
(Plains Indians)

Astronomic time

Cosmic Calendar Ephemeris Galactic year Metonic cycle Milankovitch cycles

Geologic time

Concepts

Deep time Geological history of Earth Geological time units

Standards

Global Standard Stratigraphic Age (GSSA) Global Boundary Stratotype Section and Point (GSSP)

Methods

Chronostratigraphy Geochronology Isotope geochemistry Law of superposition Luminescence dating Samarium–neodymium dating

Chronological dating

Absolute dating

Amino acid racemisation Archaeomagnetic dating Dendrochronology Ice core Incremental dating Lichenometry Paleomagnetism Radiometric dating

Radiocarbon Uranium–lead Potassium–argon

Tephrochronology Luminescence dating Thermoluminescence dating

Relative dating

Fluorine absorption Nitrogen dating Obsidian hydration Seriation Stratigraphy

Genetic methods

Molecular clock

Linguistic methods

Glottochronology

Related topics

Chronicle New Chronology Periodization Synchronoptic view Timeline Year
Year
zero Circa Floruit Terminus post quem ASPRO chronology

Portal

Authority control

.