Julian calendar Warning: You are not logged in. Your IP address will be publicly visible if you make any edits. If you log in or create an account, your edits will be attributed to your username, along with other benefits.Anti-spam check. Do not fill this in! =={{anchor|Motivation}}History== ===Motivation=== The ordinary year in the previous Roman calendar consisted of 12 months, for a total of 355 days. In addition, a 27- or 28-day [[intercalary month]], the [[Mercedonius|Mensis Intercalaris]], was sometimes inserted between 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.<ref>T H Key, "A Dictionary of Greek and Roman Antiquities" (article ''Calendarium''), London, 1875, available at [https://penelope.uchicago.edu/Thayer/E/Roman/Texts/secondary/SMIGRA*/Calendarium.html].</ref> Some say the ''mensis intercalaris'' always had 27 days and began on either the first or the second day after the Terminalia (23 February).<ref>Blackburn, B & Holford-Strevens, L ''The Oxford Companion to the Year'', Oxford University Press, 1999, reprinted with corrections, 2003, pp. 669–70.</ref> 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 [[official|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.<ref>Censorinus, [https://penelope.uchicago.edu/Thayer/L/Roman/Texts/Censorinus/text*.html#20.7 ''De die natali'' 20.7] {{In lang|la}} Latin)</ref> 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]] 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.<ref name="Varro">Varro, [https://penelope.uchicago.edu/Thayer/E/Roman/Texts/Varro/de_Re_Rustica/1*.html#28 ''On Agriculture'' I.1.28.]</ref> A century later, when [[Pliny the Elder|Pliny]] dated the [[winter solstice]] to 25 December because the sun entered the 8th degree of Capricorn on that date,<ref>Pliny, ''Natural History:'' [https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.02.0137%3Abook%3D18%3Achapter%3D59 ''(Book 18, LIX / LXVI / LXVIII / LXXIV)''.]</ref> this stability had become an ordinary fact of life. === Context of the reform === Although the approximation of {{frac|365|1|4}} days for the tropical year had been known for a long time,<ref>{{cite journal|first=R. A.|last=Parker|title=Ancient Egyptian Astronomy|journal=Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences|volume=276|issue=1257|date=May 1974|pages=51–65|jstor=74274}}</ref> ancient [[solar calendar]]s had used less precise periods, resulting in gradual misalignment of the calendar with the seasons. The [[octaeteris]], a cycle of eight [[Lunar calendar|lunar years]] popularised by [[Cleostratus]] (and also commonly attributed to [[Eudoxus of Cnidus|Eudoxus]]) which was used in some early Greek calendars, notably in [[Attic calendar|Athens]], is 1.53 days longer than eight [[Julian year (astronomy)|mean Julian years]]. The length of nineteen years in the [[Metonic cycle|cycle of Meton]] was 6,940 days, six hours longer than the mean Julian year. The mean Julian year was the basis of the [[Callippic cycle|76-year cycle]] devised by [[Callippus]] (a student under Eudoxus) to improve the Metonic cycle. In Persia (Iran) after the reform in the [[Iranian calendars#Old Persian calendar|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 [[March equinox|vernal equinox]] at the rate of approximately one day every four years.<ref>Hartner, Willy. "The young Avestan and Babylonian calendars and the antecedents of precession." Journal for the History of Astronomy 10 (1979): 1. pp. 1–22. [[doi:10.1177/002182867901000102]]</ref><ref>Stern, Sacha. ''Calendars in antiquity: Empires, states, and societies''. Oxford University Press, 2012., p. 178.</ref> 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 48 BC and soon became embroiled in the Ptolemaic dynastic war, especially after [[Cleopatra VII|Cleopatra]] managed to be "introduced" to him in [[Alexandria]]. Caesar imposed a peace, and a banquet was held to celebrate the event.<ref name="Book 10">Lucan, ''[[Pharsalia]]:'' [http://mcllibrary.org/Pharsalia/book10.html ''Book 10''.]</ref> [[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<ref name="Book 10" /> (Eudoxus was popularly credited with having determined the length of the year to be {{frac|365|1|4}} days).<ref>Émile Biémont, ''Rythmes du temps, astronomie et calendriers'', éd. De Boeck (Bruxelles), 2000 ({{ISBN|2-8041-3287-0}}), p. 224.</ref> 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 47 BC.<ref>Suetonius, [https://penelope.uchicago.edu/Thayer/E/Roman/Texts/Suetonius/12Caesars/Julius*.html#52 ''Caesar'' 52.1.] {{Webarchive|url=https://archive.today/20120530163202/http://penelope.uchicago.edu/Thayer/E/Roman/Texts/Suetonius/12Caesars/Julius*.html#52 |date=2012-05-30 }}</ref> Caesar returned to 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.<ref>Plutarch, [https://penelope.uchicago.edu/Thayer/E/Roman/Texts/Plutarch/Lives/Caesar*.html#59 ''Lives of the Noble Grecians and Romans'': Caesar 59].</ref> Pliny says that Caesar was aided in his reform by the astronomer [[Sosigenes of Alexandria]]<ref>Pliny, ''Natural History:'' [https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.02.0137%3Abook%3D18%3Achapter%3D57 ''(Book 18, LVII)''.]</ref> 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.<ref>Encyclopædia Britannica [https://www.britannica.com/EBchecked/topic/555018/Sosigenes-of-Alexandria Sosigenes of Alexandria].</ref> 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 {{frac|365|1|4}} days of Greek astronomy. According to Macrobius, Caesar was assisted in this by a certain Marcus Flavius.<ref>Macrobius, [https://penelope.uchicago.edu/Thayer/L/Roman/Texts/Macrobius/Saturnalia/1*.html#14.2 ''Saturnalia'' I.14.2] (Latin).</ref> === Adoption of the Julian calendar === {{more citations needed section|date=December 2013}} 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 [[intercalation (timekeeping)|intercalated]] every four years.<ref>This section is based on S. Stern, ''Calendars in Antiquity'' (OUP 2012) pp. 259–297.</ref><ref>{{Cite book|url=https://books.google.com/books?id=tiMZAI4oS-MC|title=Calendars in Antiquity: Empires, States, and Societies|last=Stern|first=Sacha|date=2012|publisher=OUP Oxford|isbn=978-0-19-958944-9|pages=259–297|language=en}}</ref> The reformed calendars typically retained many features of the unreformed calendars. In many cases, the New Year was not on 1 January, the leap day was not on the [[bissextus|traditional 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".<ref>Studied in detail in W. Kubitschek, ''Die Kalendarbücher von Florenz, Rom und Leyden'' (Vienna, 1915).</ref> The three most important of these calendars are the [[Coptic calendar|Alexandrian calendar]] and the [[Ancient Macedonian calendar]]─which had two forms: the Syro-Macedonian and the [[Roman Asia|'Asian']] calendars. Other reformed calendars are known from [[Cappadocia]], [[Cyprus]] and the cities of (Roman) Syria and Palestine. Unreformed calendars continued to be used in [[Gaul]] (the [[Coligny calendar]]), Greece, Macedon, the Balkans and parts of Palestine, most notably in Judea. The Asian calendar was an adaptation of the [[Ancient Macedonian calendar]] used in the [[Asia (Roman province)|Roman 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{{nbsp}}BC by the proconsul [[Paullus Fabius Maximus]]. It renamed the first month Dios as {{lang|la|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's birthday. Summary: Please note that all contributions to Christianpedia may be edited, altered, or removed by other contributors. 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