History of calendars

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The history of calendars covers practices with ancient roots as people created and used various methods to keep track of days and larger divisions of time. Calendars commonly serve both cultural and practical purposes and are often connected to astronomy and agriculture.

Archeologists have reconstructed methods of

The Vikram Samvat has been used by Hindus and Sikhs. One of several regional Hindu calendars in use on the Indian subcontinent, it is based on twelve synodic lunar months and 365 solar days. The lunar year begins with the new moon of the month of Chaitra. This day, known as Chaitra Sukhladi, is a restricted (optional) holiday in India. A number of ancient and medieval inscriptions used the Vikram Samvat. Although it was purportedly named after the legendary king Vikramaditya Samvatsara (‘Samvat’ in short), ‘Samvat’ is a Sanskrit term for ‘year’. Emperor Vikramaditya of Ujjain started Vikram Samvat in 57 BC and it is believed that this calendar follows his victory over the Saka in 56 B.C.

A larger number of calendar systems of the ancient East appear in the Iron Age archaeological record, based on the Assyrian and Babylonian calendars. This includes the calendar of the Persian Empire, which in turn gave rise to the Zoroastrian calendar as well as the Hebrew calendar.

Calendars in antiquity were usually

In the 11th century in Persia, a calendar reform led by Khayyam was announced in 1079, when the length of the year was measured as 365.24219858156 days.^[4] Given that the length of the year is changing in the sixth decimal place over a person's lifetime, this is outstandingly accurate. For comparison the length of the year at the end of the 19th century was 365.242196 days, while at the end of the 20th century it was 365.242190 days.^[4][5]

The Gregorian calendar was introduced as a refinement of the Julian calendar in 1582, and is today in worldwide use as the "de facto" calendar for secular purposes.

Etymology

The term calendars itself is taken from the calends, the term for the first day of the month in the Roman calendar, related to the verb calare "to call out", referring to the calling or the announcement that the new moon was just seen. Latin calendarium meant "account book, register", as accounts were settled and debts were collected on the calends of each month.

The Latin term was adopted in Old French as calendier and from there into Middle English as calender by the 13th century. The spelling calendar is from Early Modern English.

Prehistory

A number of prehistoric structures have been proposed as having had the purpose of timekeeping (typically keeping track of the course of the

In Victoria, Australia, a Wurdi Youang stone arrangement could date back more than 11,000 years.^[1] This estimate is based on the inaccuracy of the calendar, which is consistent with how the Earth's supposed orbit is thought to have changed during that time.^{[clarification needed][6]} The site is found near the world's oldest known site of permanent aquaculture.

A mesolithic arrangement of twelve pits and an arc found in Warren Field, Aberdeenshire, Scotland, dated to roughly 8,000 BC, has been described as a lunar calendar and was dubbed the "world's oldest known calendar" in 2013.^[7]

A ceramic artefact from Bulgaria, known as the Slatino furnace model, dated to roughly 5,000 BC, has been pronounced by local archaeologists and media to be the oldest known calendar representation, a claim not endorsed in mainstream views.^[8]

The Vučedol culture archeological findings in Vinkovci in modern-day Croatia included a ceramic vessel dated to 2,600 BC bearing inscribed ideograms of celestial objects, that was interpreted as an astral calendar, the oldest one in Europe that shows the year starting at the dusk of the first day of spring.

Ancient Near East

The ancient

Although the earliest evidence of Iranian calendrical traditions is from the

Old Persian inscriptions and tablets indicate that early Iranians used a 360-day calendar based on the solar observation directly and modified for their beliefs. Days were not named. The months had two or three divisions depending on the phase of the moon. Twelve months of 30 days were named for festivals or activities of the pastoral year. A 13th month was added every six years to keep the calendar synchronized with the seasons.

Zoroastrian calendar

The first calendars based on Zoroastrian cosmology appeared in the later Achaemenid period (650 to 330 BC). They evolved over the centuries, but month names changed little until now.

The unified

When in April of AD 224 the Parthian dynasty fell and was replaced by the Sasanid, the new king, Ardashir I, abolished the official Babylonian calendar and replaced it with the Zoroastrian. This involved a correction to the places of the gahanbar, which had slipped back in the seasons since they were fixed. These were placed eight months later, as were the epagemonai, the 'Gatha' or 'Gah' days after the ancient Zoroastrian hymns of the same name. Other countries, such as the Armenians and Choresmians, did not accept the change.

The formation of the current Persian calendar in the 11th century

Cowell quotes the Calcutta Review No 59:

When the Malik Shah determined to reform the calendar, Omar was one of the eight learned men employed to do it, the result was the Jalali era (so called from Jalal-ud-din, one of the king's names) – 'a computation of time,' says Gibbon, 'which surpasses the Julian, and approaches the accuracy of the Gregorian style.'

Khayyam measured the length of the year as 365.24219858156 days. Two comments on this result. Firstly it shows an incredible confidence to attempt to give the result to this degree of accuracy. We know now that the length of the year is changing in the sixth decimal place over a person's lifetime. Secondly it is outstandingly accurate. For comparison the length of the year at the end of the 19th century was 365.242196 days, while today it is 365.242190 days.^[13]

Classical Greece

The Greeks, as early as the time of Homer, appear to have been familiar with the division of the year into the twelve lunar months but no intercalary month Embolimos or day is then mentioned. Independent of the division of a month into days, it was divided into periods according to the increase and decrease of the moon. Thus, the first day or new moon was called Noumenia. The month in which the year began, as well as the names of the months, differed among the states, and in some parts even no names existed for the months, as they were distinguished only numerically, as the first, second, third, fourth month, etc.

The

The table of Greek Olympiads, following the four-year cycles between the Olympic Games from 1 July 776 BC, continued until the end of the 4th century AD.^[16] The Babylonian Era of Nabonassar, beginning on 26 February 747 BC, was used by the Greeks of Alexandria.^[16] It was later known in the Middle Ages from the works of Ptolemy.^[16]

Hellenistic period

The Greek calendars were greatly diversified by the Hellenistic period, with separate traditions in every Greek state. Of primary importance for the reconstruction of the regional Greek calendars is the calendar of Delphi, because of the numerous documents found there recording the manumission of slaves, many of which are dated both in the Delphian and in a regional calendar.

The Macedonian Era of the Seleucids, which began with the conquest of Babylon by Seleucus I Nicator in 312 BC.^[16] It became widely used in the Levant.^[16] The Jews knew it as the "era of contracts", and used it in Europe until the 15th century.^[16]

The Roman Republican calendar numbered years based on the

Most of the regional

Before the

Timekeeping was important to Vedic rituals, and

The Jyotisha text Brahma-siddhanta, probably composed in the 5th century AD, discusses how to use the movement of planets, sun and moon to keep time and calendar.[26] This text also lists trigonometry and mathematical formulae to support its theory of orbital, predict planetary positions and calculate relative mean positions of celestial nodes and apsides.^[26] The text is notable for presenting very large integers, such as 4.32 billion years as the lifetime of the current universe.^[27]

Water clock and sun dials are mentioned in many ancient Hindu texts such as the Arthashastra.^[28][29] The Jyotisha texts present mathematical formulae to predict the length of day time, sun rise and moon cycles.^[30][31][32]

The modern Hindu calendar, sometimes referred to as Panchanga, is a collective term for the various lunisolar calendars traditionally used in Hinduism. They adopt a similar underlying concept for timekeeping, but differ in their relative emphasis on the moon cycle or the sun cycle, the names of months and when they consider the New Year to start.^[33][34] The ancient Hindu calendar is similar in conceptual design to the Jewish calendar, but different from the Gregorian calendar.^[35] Unlike the Gregorian calendar which adds additional days to the lunar month to adjust for the mismatch between twelve lunar cycles (354 lunar days)^[36] and nearly 365 solar days, the Hindu calendar maintains the integrity of the lunar month, but inserts an extra full month according to complex rules, every few years, to ensure that the festivals and crop related rituals fall in the appropriate season.^[35][37]

The Hindu calendars have been in use in the Indian subcontinent since ancient times, and remain in use by the

Hindus in India and Nepal, particularly to set Hindu festival dates. Early Buddhist and Jain communities of India adopted the ancient Hindu calendar, later Vikrami calendar and then local Buddhist calendars. Buddhist and Jain festivals continue to be scheduled according to a lunar system in the luni-solar calendar.^[38][39][40]

Roman Empire

Main article: Julian calendar

The old Roman year had 304 days divided into 10 months, beginning with March. However the ancient historian Livy gave credit to the second early Roman king Numa Pompilius for devising a calendar of 12 months. The extra months Ianuarius and Februarius had been invented, supposedly by Numa Pompilius, as stop-gaps.^[16] Julius Caesar realized that the system had become inoperable, so he effected drastic changes in the year of his third consulship.^[16] The New Year in 709 AUC began on 1 January and ran over 365 days until 31 December.^[16] Further adjustments were made under Augustus, who introduced the concept of the "leap year" in 757 AUC (AD 4)^{[conversion is 1 year out]}.^[16] The resultant Julian calendar remained in almost universal use in Europe until 1582,^[16] and in some countries until as late as the twentieth century.

Dionysian era in the Carolingian period

.

In the Roman Empire, the AUC year could be used alongside the consular year, so that the consulship of

Marcus Aemilius Lepidus, as 708 AUC (or 46 BC), and the fourth consulship of Gaius Julius Caesar as 709 AUC (or 45 BC).^[16]

The seven-day week has a tradition reaching back to the ancient Near East, but the introduction of the "planetary week" which remains in modern use dates to the Roman Empire period (see also names of the days of the week).

Middle Ages

Christian Europe

Main articles: Date of Easter and Julian calendar

The oldest

Calendar of Filocalus, produced in AD 354. A more extensive martyrology was compiled by Jerome in the early 5th century. Jean Mabillon published a calendar of the church of Carthage made in ca. AD 483. The Anno Domini epoch is introduced in the 6th century.^[16] Extant calendars of the early medieval period are based on Jerome's system of numbering of the years of the Metonic cycle, later called the Golden Numbers. A Carolingian-era calendar published by Luc d'Achery is entitled Incipit Ordo Solaris Anni cum Litteris a S. Hieronymo superpositis, ad explorandum Septimanae Diem, et Lunae Aetatem investigandam in unoquoque Die per xix Annos. ("here begins the order of the solar year with the letters placed by Saint Jerome, for the purpose of finding the day of the week and the age of the Moon for any day within [the cycle of] 19 years").^[41] The Leiden Aratea, a Carolingian copy (dated 816) of an astronomical treatise of Germanicus, is an important source for the transmission of the ancient Christian calendar to the medieval period.^[42]

In the 8th century, the

regnal years, and usage of AD only gradually became common in Europe from the 11th to the 14th centuries.^{[citation needed]} In 1422, Portugal became the last Western European country to adopt the Anno Domini system.^{[citation needed}

]

The

Germanic calendars

were based on lunar months, the new Icelandic calendar introduced a purely solar reckoning, with a year having a fixed number of weeks (52 weeks or 364 days). This necessitated the introduction of "leap weeks" instead of the Julian leap days.

In 1267, the medieval scientist Roger Bacon stated the times of full moons as a number of hours, minutes, seconds, thirds, and fourths (horae, minuta, secunda, tertia, and quarta) after noon on specified calendar dates.^[44] Although a third for 1⁄60 of a second remains in some languages, for example Arabic ثالثة, the modern second is further divided decimally.

Rival calendar eras to Anno Domini remained in use in Christian Europe.^[16] In Spain, the "Era of the Caesars" was dated from Octavian's conquest of Iberia in 39 BC.^[16] It was adopted by the Visigoths and remained in use in Catalonia until 1180, Castille until 1382 and Portugal until 1415.^[16]

For chronological purposes, the flaw of the Anno Domini system was that dates have to be reckoned backwards or forwards according as they are BC or AD. According to the

Archbishop Ussher in 1650, would pick 4004 BC.^[45]

Islamic calendar

The

Dhu al-Hijjah

AH 10 (Julian date: 6 March 632). This resulted in an observationally based lunar calendar shifting relative to the seasons of the solar year.

See also: Fasli calendar

During the Mughal rule, land taxes were collected from Bengali people according to the Islamic Hijri calendar. This calendar was a lunar calendar, and its new year did not coincide with the solar agricultural cycles. According to some sources, Mughal Emperor Akbar asked his royal astronomer Fathullah Shirazi to create a new calendar by combining the lunar Islamic calendar and solar Hindu calendar already in use, and this was known as Fasholi shan (harvest calendar).^[46][47] According to Amartya Sen, Akbar's official calendar "Tarikh-ilahi" with the zero year of 1556 AD was a blend of pre-existing Hindu and Islamic calendars. It was not used much in India outside of Akbar's Mughal court, and after his death the calendar he launched was abandoned. However, adds Sen, there are traces of the "Tarikh-ilahi" that survive in the Bengali calendar.^[48] Some historians attribute the Bengali calendar to the 7th-century Hindu king Shashanka.^[46][49][50]

Other

The ancient Taichu calendar of China was refined in the medieval period. The Dàmíng Calendar (大明历; 大明曆; 'brightest calendar'), created in the Liang dynasty by Zu Chongzhi, introduced the equinoxes. The use of a syzygy to determine the lunar month was first described in the Tang dynasty Wùyín Yuán Calendar (戊寅元历; 戊寅元曆; 'earth tiger epoch calendar').

The Yuan dynasty (13th/14th century) Shòushí calendar (授时历; 授时曆; 'teaching time calendar') used spherical trigonometry to find the length of the tropical year.^[51][52][53] This calendar had a 365.2425-day year, identical to the Gregorian calendar.^[54]

A number of other epichoric calendars are tentatively reconstructed for the medieval period. Such reconstructions are mostly limited to a list of

Nominalia of the Bulgarian khans

.

Sub-Saharan African

Ethiopian Calendar

The Ge'ez or 

Orthodox Tewahedo Churches and closely follows the Coptic Christian calendar

.

Nigerian Calendars

The 

Orisa

.

Ghana/West African

The 

seven-day week

 is known as nnawɔtwe (eight-days). The combination of these two system resulted in periods of 40 days, known as adaduanan (meaning "forty days").

Xhosa Calendar

The traditional isiXhosa names for months of the year poetically come from names of stars, plants, and flowers that grow or seasonal changes that happen at a given time of year in Southern Africa.

The Xhosa year traditionally begins in June and ends in May when the brightest star visible in the Southern Hemisphere, Canopus, signals the time for harvesting.

Mesoamerica

Main article: Maya calendar

Of all the ancient calendar systems, the

Mesoamerican systems are the most complex. The Mayan calendar had two years, the 260-day Sacred Round, or tzolkin, and the 365-day Vague Year, or haab.^[55]

The Sacred Round of 260 days is composed of two smaller cycles: the numbers 1 through 13, coupled with 20 different day names: Imix, Ik, Akbal, Kan, Chicchan, Cimi, Manik, Lamat, Muluc, Oc, Chuen, Eb, Ben, Ix, Men, Cib, Caban, Eiznab, Cauac, and Ahau. The Sacred Round was used to determine important activities related to the gods and humans: name individuals, predict the future, decide on auspicious dates for battles, marriages, and so on.^[55]

The two cycles of 13 and 20 intermesh and are repeated without interruption: the cycle would begin with 1 Imix, then 2 Ik, then 3 Akbal and so on until the number 13 was reached, at which point the number cycle was restarted so 13 Ben would be followed by 1 Ix, 2 Men and so on. This time Imix would be numbered 8. The cycle ended after 260 days, with the last day being 13 Ahau.^[55]

The Vague Year of 365 days is similar to the modern

Uayeb, and was considered a time which could hold danger, death and bad luck.^[55]

The Vague Year began with the month of Pop. The Maya 20-day month always begins with the seating of the month, followed by days numbered 1 to 19, then the seating of the following month, and so on. This ties in with the Maya notion that each month influences the next. The Maya new year would start with 1 Pop, followed by 2 Pop, all the way through to 19 Pop, followed by the seating of the month of Uo, written as 0 Uo, then 1 Uo, 2 Uo and so on. These two cycles coincided every 52 years. The 52-year period of time was called a "bundle" and was similar to a modern-day century.[55]

Modern calendars

Further information: List of calendars and Calendar reform

While the Gregorian calendar is now in worldwide use for secular purposes, various medieval or ancient calendars remain in regional use for religious or social purposes, including the Julian calendar, the Hebrew calendar, the Islamic calendar, various Hindu calendars, the Zoroastrian calendar, etc.

There are also various modern calendars that see limited use, either created for the use of new religious movements or reformed versions of older religious calendars, or calendars introduced by regionalist or nationalist movements.

• Javanese calendar (1633)
• Jōkyō calendar (1685)
• French Republican calendar (1793)
• Baháʼí calendar (1873)
• Solar Hijri calendar (1925)
• Pataphysical calendar
  (1949)
• Indian national calendar (1957)
• Discordian calendar (1963)
• Juche calendar (1997)

See also

• Names of the days of the week
• History of timekeeping devices

References

1. ^ ^{a b} Hegarty, Stephanie (6 October 2011). "Stargazing at an 'Aboriginal Stonehenge'". BBC News. Retrieved 13 January 2019.
2. ^ "'World's oldest calendar' discovered in Scottish field". BBC News. 15 July 2013. Retrieved 20 January 2023.
3. ^ "Religion in the Etruscan period" in Roman religion in Encyclopædia Britannica
4. ^ ^{a b} "Khayyam biography". www-history.mcs.st-and.ac.uk. Retrieved 2 January 2017.
5. ^ "Time - Lengths of years and months | Britannica".
6. ^ Fitzsimmons, Hamish (12 October 2016). "Ancient Aboriginal site dubbed 'Australia's Stonehenge' could be world's oldest observatory". ABC News. Retrieved 13 January 2019.
7. ^ "Scotland lunar-calendar find sparks Stone Age rethink". phys.org. Archived from the original on 9 August 2013.
8. ^ Bailey D., 2000, Balkan Prehistory: Exclusion, Incorporation and Identity, London:Routledge p. 325
9. ^ "Mesopotamia, Calendar". History-world.org. International World History Project. Archived from the original on 27 November 2005. Retrieved 14 August 2008.
10. ^ ^{a b} "Calendar". Encyclopædia Britannica Online. Encyclopædia Britannica. Retrieved 14 May 2019.
11. ^ Yust, Walter (1947). "Encyclopædia Britannica: A New Survey of Universal Knowledge". Encyclopædia Britannica. p. 576.
12. ^ (Panaino 1990)
13. ^ "Omar Khayyam - Biography". Maths History.
14. ^ Ginzel: Handbuch der Mathematischen und Technischen Chronologie. Vol. 2. Germany: F.K. 1911. pp. 335–336.
15. ^ "Attic Calendar. Date converter. Convert any date to any calendar". www.epistemeacademy.org.
16. ^ ^{a b c d e f g h i j k l m n o p q r s} Davies, p 267
17. ^ I Ching calendar at Wikibooks
18. ^ ^{a b} Monier Monier-Williams (1923). A Sanskrit–English Dictionary. Oxford University Press. p. 353.
19. ^
    ISBN 0-8239-2287-1
    , pages 326–327
20. ^ Friedrich Max Müller (1860). A History of Ancient Sanskrit Literature. Williams and Norgate. pp. 210–215.
21. ^ Plofker 2009, pp. 41–42.
22. ISBN 978-94-011-4179-6
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23. ^ Friedrich Max Müller (1860). A History of Ancient Sanskrit Literature So Far as it Illustrates the Primitive Religion of the Brahmans. Williams and Norgate. p. 110.
24. ^ Ohashi 1993, p. 719.
25. ^ ^{a b} Pingree 1973, p. 1.
26. ^ ^{a b} Plofker 2009, pp. 67–68.
27. ^ Plofker 2009, pp. 68–71.
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30. ^ Ohashi 1993, pp. 185–251.
31. ^ Plofker 2009, pp. 35–40.
32. ^ Winternitz 1963, p. 269.
33. ^ B. Richmond (1956). Time Measurement and Calendar Construction. Brill Archive. pp. 80–82. Retrieved 18 September 2011.
34. ISBN 978-0-7914-7082-4
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35. ^
    ISBN 978-0-19-874557-0
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36. ISBN 978-0-521-23594-5
    ., Quote: "the lunar year consists of 354 days".
37. ISBN 978-0-69112-04-85
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38. ISBN 978-1-58340-375-4
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39. ISBN 978-0-85771-392-6
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41. ^ R.T. Hampson, Medii Aevi Kalendarium (1841), 389ff.
42. ^ Bruce S. Eastwood, The Revival of Planetary Astronomy in Carolingian and Post-Carolingian Europe (2002).
43. ^ Bede. "Historiam Ecclesiasticam Gentis Anglorum: Liber Primus" (in Latin). Thelatinlibrary.com. Retrieved 6 July 2008.
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45. ^ ^{a b c d} Davies, p 268
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    ISBN 978-0-8108-8024-5
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47. ^ "Pahela Baishakh". Banglapedia. Dhaka, Bangladesh: Asiatic Society of Bangladesh. 2015.
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50. ISBN 978-0-14-341678-4
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51. Bibcode:1959scc3.book.....N
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54. ISBN 978-981-229-376-3
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55. ^ ^{a b c d e} "Maya civilization". Civilization.ca. Archived from the original on 5 March 2008. Retrieved 3 April 2008.

Works cited

• Ohashi, Yukio (1993). "Development of Astronomical Observations in Vedic and post-Vedic India". Indian Journal of History of Science. 28 (3).
• Panaino, Antonio (1990). "CALENDARS, i. Pre-Islamic calendars". Encyclopaedia Iranica. Vol. 4.
  ISBN 0-7100-9132-X
  .
• Pingree, David (1973). "The Mesopotamian Origin of Early Indian Mathematical Astronomy". Journal for the History of Astronomy. 4 (1). SAGE: 1–12.
  S2CID 125228353
  .
• ISBN 978-0-691-12067-6
  .
• ISBN 978-81-208-0056-4
  .

External links

• "The Calendar", BBC Radio 4 discussion with Robert Poole, Kristen Lippincott and Peter Watson (In Our Time, 19 December 2002)