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64-507: The Oxford University Press originally held a monopoly on publishing almanacs. The almanacs traditionally included engravings and information about Oxford University, including the Heads of Colleges and a university calendar . No almanack appeared in 1675, but it had been published annually since 1676. Engravers and artists have included James Basire , Michael Burghers , J. M. W. Turner , and John Piper . Petter's The Oxford Almanacks lists

128-597: A business. It is used for budgeting, keeping accounts, and taxation. It is a set of 12 months that may start at any date in a year. The US government's fiscal year starts on 1 October and ends on 30 September. The government of India's fiscal year starts on 1 April and ends on 31 March. Small traditional businesses in India start the fiscal year on Diwali festival and end the day before the next year's Diwali festival. Hindu calendars Traditional The Hindu calendar , also called Panchanga ( Sanskrit : पञ्चाङ्ग ),

192-559: A calendar based on the reign of their current sovereign. For example, the year 2006 in Japan is year 18 Heisei, with Heisei being the era name of Emperor Akihito . An astronomical calendar is based on ongoing observation; examples are the religious Islamic calendar and the old religious Jewish calendar in the time of the Second Temple . Such a calendar is also referred to as an observation-based calendar. The advantage of such

256-407: A calendar includes more than one type of cycle or has both cyclic and non-cyclic elements. Most calendars incorporate more complex cycles. For example, the vast majority of them track years, months, weeks and days. The seven-day week is practically universal, though its use varies. It has run uninterrupted for millennia. Solar calendars assign a date to each solar day . A day may consist of

320-437: A calendar is that it is perfectly and perpetually accurate. The disadvantage is that working out when a particular date would occur is difficult. An arithmetic calendar is one that is based on a strict set of rules; an example is the current Jewish calendar . Such a calendar is also referred to as a rule-based calendar. The advantage of such a calendar is the ease of calculating when a particular date occurs. The disadvantage

384-435: A calendar provides a way to determine when to start planting or harvesting, which days are religious or civil holidays , which days mark the beginning and end of business accounting periods, and which days have legal significance, such as the day taxes are due or a contract expires. Also, a calendar may, by identifying a day, provide other useful information about the day such as its season. Calendars are also used as part of

448-417: A complete timekeeping system: date and time of day together specify a moment in time . In the modern world, timekeepers can show time, date, and weekday. Some may also show the lunar phase. The Gregorian calendar is the de facto international standard and is used almost everywhere in the world for civil purposes. The widely used solar aspect is a cycle of leap days in a 400-year cycle designed to keep

512-557: A lunar calendar and also the number of months in a year in a lunisolar calendar. This is generally known as intercalation . Even if a calendar is solar, but not lunar, the year cannot be divided entirely into months that never vary in length. Cultures may define other units of time, such as the week, for the purpose of scheduling regular activities that do not easily coincide with months or years. Many cultures use different baselines for their calendars' starting years. Historically, several countries have based their calendars on regnal years ,

576-522: A lunar system. The Buddhist calendar and the traditional lunisolar calendars of Cambodia , Laos , Myanmar , Sri Lanka and Thailand are also based on an older version of the Hindu calendar. Similarly, the ancient Jain traditions have followed the same lunisolar system as the Hindu calendar for festivals, texts and inscriptions. However, the Buddhist and Jain timekeeping systems have attempted to use

640-457: A number of systems of which intercalary months became most used, that is adding another month every 32.5 months on average. As their calendar keeping and astronomical observations became more sophisticated, the Hindu calendar became more sophisticated with complex rules and greater accuracy. According to Scott Montgomery, the Siddhanta tradition at the foundation of Hindu calendars predate

704-563: A reference date. This applies for the Julian day or Unix Time . Virtually the only possible variation is using a different reference date, in particular, one less distant in the past to make the numbers smaller. Computations in these systems are just a matter of addition and subtraction. Other calendars have one (or multiple) larger units of time. Calendars that contain one level of cycles: Calendars with two levels of cycles: Cycles can be synchronized with periodic phenomena: Very commonly

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768-597: A rudimentary level. Later medieval era texts such as the Yavana-jataka and the Siddhanta texts are more astrology-related. Hinduism and Buddhism were the prominent religions of southeast Asia in the 1st millennium CE, prior to the Islamic conquest that started in the 14th century. The Hindus prevailed in Bali, Indonesia, and they have two types of Hindu calendar. One is a 210-day based Pawukon calendar which likely

832-750: A sermon given on 9 Dhu al-Hijjah AH 10 (Julian date: 6 March 632). This resulted in an observation-based lunar calendar that shifts relative to the seasons of the solar year. There have been several modern proposals for reform of the modern calendar, such as the World Calendar , the International Fixed Calendar , the Holocene calendar , and the Hanke–Henry Permanent Calendar . Such ideas are mooted from time to time, but have failed to gain traction because of

896-525: A similar manner to the Christian era . There are several samvat found in historic Buddhist, Hindu and Jain texts and epigraphy, of which three are most significant: Vikrama era, Old Shaka era and Shaka era of 78 CE. The Hindu calendar divides the zodiac into twelve division called rāśi ("group"). The Sun appears to move around the Earth through different divisions/constellations in the sky throughout

960-580: A solar calendar, using as a fixed point the annual sunrise reappearance of the Dog Star— Sirius , or Sothis—in the eastern sky, which coincided with the annual flooding of the Nile River. They built a calendar with 365 days, divided into 12 months of 30 days each, with 5 extra days at the end of the year. However, they did not include the extra bit of time in each year, and this caused their calendar to slowly become inaccurate. Not all calendars use

1024-575: Is a lunar calendar consisting of 12 lunar months in a year of 354 or 355 days. It is used to date events in most of the Muslim countries (concurrently with the Gregorian calendar) and used by Muslims everywhere to determine the proper day on which to celebrate Islamic holy days and festivals. Its epoch is the Hijra (corresponding to AD 622). With an annual drift of 11 or 12 days, the seasonal relation

1088-597: Is a pre-Hindu system, and another is similar to lunisolar calendar system found in South India and it is called the Balinese saka calendar which uses Hindu methodology. The names of month and festivals of Balinese Hindus, for the most part, are different, though the significance and legends have some overlap. The Hindu calendar is based on a geocentric model of the Solar System . A large part of this calendar

1152-615: Is also found in the Hebrew calendar , the Chinese calendar , and the Babylonian calendar , but different from the Gregorian calendar. Unlike the Gregorian calendar which adds additional days to the month to adjust for the mismatch between twelve lunar cycles (354 lunar days) and approximately 365 solar days, the Hindu calendar maintains the integrity of the lunar month, but inserts an extra full month, once every 32–33 months, to ensure that

1216-601: Is defined based on the movement of the Sun and the Moon around the Earth (saura māna and cāndra māna respectively). Furthermore, it includes synodic , sidereal , and tropical elements. Many variants of the Hindu calendar have been created by including and excluding these elements (solar, lunar, lunisolar etc.) and are in use in different parts of India. Samvat refers to era of the several Hindu calendar systems in Nepal and India , in

1280-423: Is imperfect accuracy. Furthermore, even if the calendar is very accurate, its accuracy diminishes slowly over time, owing to changes in Earth's rotation. This limits the lifetime of an accurate arithmetic calendar to a few thousand years. After then, the rules would need to be modified from observations made since the invention of the calendar. The early Roman calendar , created during the reign of Romulus , lumped

1344-451: Is one of various lunisolar calendars that are traditionally used in the Indian subcontinent and Southeast Asia , with further regional variations for social and Hindu religious purposes. They adopt a similar underlying concept for timekeeping based on sidereal year for solar cycle and adjustment of lunar cycles in every three years, but differ in their relative emphasis to moon cycle or

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1408-691: Is repeated approximately every 33 Islamic years. Various Hindu calendars remain in use in the Indian subcontinent, including the Nepali calendars , Bengali calendar , Malayalam calendar , Tamil calendar , Vikrama Samvat used in Northern India, and Shalivahana calendar in the Deccan states. The Buddhist calendar and the traditional lunisolar calendars of Cambodia , Laos , Myanmar , Sri Lanka and Thailand are also based on an older version of

1472-501: Is the Islamic calendar . Alexander Marshack, in a controversial reading, believed that marks on a bone baton ( c.  25,000 BC ) represented a lunar calendar. Other marked bones may also represent lunar calendars. Similarly, Michael Rappenglueck believes that marks on a 15,000-year-old cave painting represent a lunar calendar. A lunisolar calendar is a lunar calendar that compensates by adding an extra month as needed to realign

1536-406: Is the designation of a single and specific day within such a system. A calendar is also a physical record (often paper) of such a system. A calendar can also mean a list of planned events, such as a court calendar , or a partly or fully chronological list of documents, such as a calendar of wills. Periods in a calendar (such as years and months) are usually, though not necessarily, synchronized with

1600-632: Is used in Iran and some parts of Afghanistan . The Assyrian calendar is in use by the members of the Assyrian community in the Middle East (mainly Iraq, Syria, Turkey, and Iran) and the diaspora. The first year of the calendar is exactly 4750 years prior to the start of the Gregorian calendar. The Ethiopian calendar or Ethiopic calendar is the principal calendar used in Ethiopia and Eritrea , with

1664-747: The Babylonian calendar dating from the Iron Age , among them the calendar system of the Persian Empire, which in turn gave rise to the Zoroastrian calendar and the Hebrew calendar . A great number of Hellenic calendars were developed in Classical Greece , and during the Hellenistic period they gave rise to the ancient Roman calendar and to various Hindu calendars . Calendars in antiquity were lunisolar , depending on

1728-720: The Bronze Age Egyptian and Sumerian calendars. During the Vedic period India developed a sophisticated timekeeping methodology and calendars for Vedic rituals. According to Yukio Ohashi, the Vedanga calendar in ancient India was based on astronomical studies during the Vedic Period and was not derived from other cultures. A large number of calendar systems in the Ancient Near East were based on

1792-572: The Chinese language in the 2nd and 3rd centuries CE, and the Rigvedic passages on astronomy are found in the works of Zhu Jiangyan and Zhi Qian . According to Subhash Kak , the beginning of the Hindu calendar was much earlier. He cites Greek historians describing Maurya kings referring to a calendar which originated in 6676 BCE known as Saptarsi calendar. The Vikrami calendar is named after king Vikramaditya and starts in 57 BCE. Hindu scholars kept precise time by observing and calculating

1856-566: The Oromo calendar also in use in some areas. In neighboring Somalia , the Somali calendar co-exists alongside the Gregorian and Islamic calendars. In Thailand , where the Thai solar calendar is used, the months and days have adopted the western standard, although the years are still based on the traditional Buddhist calendar . A fiscal calendar generally means the accounting year of a government or

1920-522: The "calling" of the new moon when it was first 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 in Middle English as calender by the 13th century (the spelling calendar is early modern). The course of the Sun and

1984-530: The 61 days of the winter period them together as simply "winter." Over time, this period became January and February; through further changes over time (including the creation of the Julian calendar ) this calendar became the modern Gregorian calendar, introduced in the 1570s. The primary practical use of a calendar is to identify days: to be informed about or to agree on a future event and to record an event that has happened. Days may be significant for agricultural, civil, religious, or social reasons. For example,

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2048-570: The Buddha and the Mahavira's lifetimes as their reference points. The Hindu calendar is also important to the practice of Hindu astrology and zodiac system. It is also employed for observing the auspicious days of deities and occasions of fasting, such as Ekadashi . Time keeping [The current year] minus one, multiplied by twelve, multiplied by two, added to the elapsed [half months of current year], increased by two for every sixty [in

2112-603: The Christian era, once had 18 texts of which only 5 have survived into the modern era. These texts provide specific information and formulae on motions of Sun, Moon and planets, to predict their future relative positions, equinoxes, rise and set, with corrections for prograde, retrograde motions, as well as parallax. These ancient scholars attempted to calculate their time to the accuracy of a truti (29.63 microseconds). In their pursuit of accurate tracking of relative movements of celestial bodies for their calendar, they had computed

2176-687: The Hindu calendar. Most of the Hindu calendars are inherited from a system first enunciated in Vedanga Jyotisha of Lagadha, standardized in the Sūrya Siddhānta and subsequently reformed by astronomers such as Āryabhaṭa (AD 499), Varāhamihira (6th century) and Bhāskara II (12th century). The Hebrew calendar is used by Jews worldwide for religious and cultural affairs, also influences civil matters in Israel (such as national holidays ) and can be used business dealings (such as for

2240-626: The Malayalam calendar broadly retains the phonetic Sanskrit names, the Bengali and Tamil calendars repurpose the Sanskrit lunar month names (Chaitra, Vaishaka etc.) as follows: The solar months ( rāśi ) along with their equivalent names in the Bangali, Malayalam and Tamil calendar are given below: or ଭାଦ୍ର (Bhādra) (Tai) or ଫଗୁଣ (Phaguṇa) (Māsi) The solar months ( rāśi ) along with

2304-539: The Moon are the most salient regularly recurring natural events useful for timekeeping , and in pre-modern societies around the world lunation and the year were most commonly used as time units. Nevertheless, the Roman calendar contained remnants of a very ancient pre-Etruscan 10-month solar year. The first recorded physical calendars, dependent on the development of writing in the Ancient Near East , are

2368-604: The Old Calendar) and the Revised Julian Calendar (often called the New Calendar). The Revised Julian Calendar is nearly the same as the Gregorian calendar, with the addition that years divisible by 100 are not leap years , except that years with remainders of 200 or 600 when divided by 900 remain leap years, e.g. 2000 and 2400 as in the Gregorian calendar. The Islamic calendar or Hijri calendar

2432-546: The Roman Rite of the Catholic Church, and generally include the liturgical seasons of Advent , Christmas , Ordinary Time (Time after Epiphany ), Lent , Easter , and Ordinary Time (Time after Pentecost ). Some Christian calendars do not include Ordinary Time and every day falls into a denominated season. The Eastern Orthodox Church employs the use of 2 liturgical calendars; the Julian calendar (often called

2496-711: The Sun towards north for 6 months, and south for 6 months. Time keeping was important to Vedic rituals, and Jyotisha was the Vedic era field of tracking and predicting the movements of astronomical bodies in order to keep time, in order to fix the day and time of these rituals. This study is one of the six ancient Vedangas , or ancillary science connected with the Vedas – the scriptures of Vedic Sanatan Sanskriti. Yukio Ohashi states that this Vedanga field developed from actual astronomical studies in ancient Vedic Period. The texts of Vedic Jyotisha sciences were translated into

2560-447: The characteristics of the respective planetary motion. Other texts such as Surya Siddhanta dated to have been completed sometime between the 5th century and 10th century present their chapters on various deified planets with stories behind them. The manuscripts of these texts exist in slightly different versions. They present Surya, planet-based calculations and Surya's relative motion to Earth. These vary in their data, suggesting that

2624-421: The cycle of the sun or the moon . The most common type of pre-modern calendar was the lunisolar calendar , a lunar calendar that occasionally adds one intercalary month to remain synchronized with the solar year over the long term. The term calendar is taken from kalendae , the term for the first day of the month in the Roman calendar, related to the verb calare 'to call out', referring to

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2688-531: The cycles of Surya (the Sun), Moon and the planets. These calculations about the Sun appear in various astronomical texts in Sanskrit , such as the 5th-century Aryabhatiya by Aryabhata , the 6th-century Romaka by Latadeva and Panca Siddhantika by Varahamihira, the 7th-century Khandakhadyaka by Brahmagupta and the 8th-century Sisyadhivrddida by Lalla. These texts present Surya and various planets and estimate

2752-716: The dating of cheques ). Followers of the Baháʼí Faith use the Baháʼí calendar . The Baháʼí Calendar, also known as the Badi Calendar was first established by the Bab in the Kitab-i-Asma. The Baháʼí Calendar is also purely a solar calendar and comprises 19 months each having nineteen days. The Chinese , Hebrew , Hindu , and Julian calendars are widely used for religious and social purposes. The Iranian (Persian) calendar

2816-418: The duration of the year aligned with the solar year . There is a lunar aspect which approximates the position of the moon during the year, and is used in the calculation of the date of Easter . Each Gregorian year has either 365 or 366 days (the leap day being inserted as 29 February), amounting to an average Gregorian year of 365.2425 days (compared to a solar year of 365.2422 days). The Gregorian calendar

2880-493: The festivals and crop-related rituals fall in the appropriate season. The Hindu calendars have been in use in the Indian subcontinent since Vedic times, and remain in use by the Hindus all over the world, particularly to set Hindu festival dates. Early Buddhist communities of India adopted the ancient Vedic calendar,later Vikrami calendar and then local Buddhist calendars . Buddhist festivals continue to be scheduled according to

2944-415: The introduction of intercalary months to align the solar and the lunar years. This was mostly based on observation, but there may have been early attempts to model the pattern of intercalation algorithmically, as evidenced in the fragmentary 2nd-century Coligny calendar . The Roman calendar was reformed by Julius Caesar in 46 BC. His "Julian" calendar was no longer dependent on the observation of

3008-432: The loss of continuity and the massive upheaval that implementing them would involve, as well as their effect on cycles of religious activity. A full calendar system has a different calendar date for every day. Thus the week cycle is by itself not a full calendar system; neither is a system to name the days within a year without a system for identifying the years. The simplest calendar system just counts time periods from

3072-669: The lunar cycle. Their new year starts in spring. In regions such as Tamil Nadu and Kerala, the solar cycle is emphasized and this is called the Tamil calendar (though Tamil Calendar uses month names like in Hindu Calendar) and Malayalam calendar and these have origins in the second half of the 1st millennium CE. A Hindu calendar is sometimes referred to as Panchangam (पञ्चाङ्गम्), which is also known as Panjika in Eastern India. The ancient Hindu calendar conceptual design

3136-517: The mean diameter of the Earth, which was very close to the actual 12,742 km (7,918 mi). Hindu calendars were refined during the Gupta era astronomy by Āryabhaṭa and Varāhamihira in the 5th to 6th century. These, in turn, were based in the astronomical tradition of Vedāṅga Jyotiṣa , which in the preceding centuries had been standardised in a number of (non-extant) works known as Sūrya Siddhānta . Regional diversification took place in

3200-651: The medieval period. The astronomical foundations were further developed in the medieval period, notably by Bhāskara II (12th century). Later, the term Jyotisha evolved to include Hindu astrology . The astrological application of the Hindu calendar was a field that likely developed in the centuries after the arrival of Greek astrology with Alexander the Great , because their zodiac signs are nearly identical. The ancient Hindu texts on Jyotisha only discuss timekeeping, and never mention astrology or prophecy. These ancient texts predominantly cover astronomy, but at

3264-516: The months with the seasons. Prominent examples of lunisolar calendar are Hindu calendar and Buddhist calendar that are popular in South Asia and Southeast Asia . Another example is the Hebrew calendar, which uses a 19-year cycle . Nearly all calendar systems group consecutive days into "months" and also into "years". In a solar calendar a year approximates Earth's tropical year (that is,

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3328-469: The new moon, but followed an algorithm of introducing a leap day every four years. This created a dissociation of the calendar month from lunation . The Gregorian calendar , introduced in 1582, corrected most of the remaining difference between the Julian calendar and the solar year. The Islamic calendar is based on the prohibition of intercalation ( nasi' ) by Muhammad , in Islamic tradition dated to

3392-454: The observation of religious feast days. While the Gregorian calendar is itself historically motivated to the calculation of the Easter date , it is now in worldwide secular use as the de facto standard. Alongside the use of the Gregorian calendar for secular matters, there remain several calendars in use for religious purposes. Western Christian liturgical calendars are based on the cycle of

3456-414: The period between sunrise and sunset , with a following period of night , or it may be a period between successive events such as two sunsets. The length of the interval between two such successive events may be allowed to vary slightly during the year, or it may be averaged into a mean solar day . Other types of calendar may also use a solar day. The Egyptians appear to have been the first to develop

3520-408: The same challenge of accounting for the mismatch between the nearly 354 lunar days in twelve months, versus over 365 solar days in a year. They tracked the solar year by observing the entrance and departure of Surya (sun, at sunrise and sunset) in the constellation formed by stars in the sky, which they divided into 12 intervals of 30 degrees each. Like other ancient human cultures, Hindus innovated

3584-636: The scenes depicted and their illustrators up to 1973, and the list is continued to 1991 in Bradshaw's article in Oxoniensia (see Further Reading for both references). This article relating to the University of Oxford is a stub . You can help Misplaced Pages by expanding it . Calendar A calendar is a system of organizing days . This is done by giving names to periods of time , typically days, weeks , months and years . A date

3648-407: The solar year as a unit. A lunar calendar is one in which days are numbered within each lunar phase cycle. Because the length of the lunar month is not an even fraction of the length of the tropical year , a purely lunar calendar quickly drifts against the seasons, which do not vary much near the equator. It does, however, stay constant with respect to other phenomena, notably tides . An example

3712-783: The sun cycle and the names of months and when they consider the New Year to start. Of the various regional calendars, the most studied and known Hindu calendars are the Shalivahana Shaka (Based on the King Shalivahana , also the Indian national calendar ) found in the Deccan region of Southern India and the Vikram Samvat (Bikrami) found in Nepal and the North and Central regions of India – both of which emphasize

3776-417: The sun], is the quantity of half-months ( syzygies ). — Rigveda Jyotisha-vedanga 4 Translator: Kim Plofker The Vedic culture developed a sophisticated time keeping methodology and calendars for Vedic rituals, and timekeeping as well as the nature of solar and Moon movements are mentioned in Vedic texts. For example, Kaushitaki Brahmana chapter 19.3 mentions the shift in the relative location of

3840-415: The text were open and revised over their lives. For example, the 1st millennium CE Hindu scholars calculated the sidereal length of a year as follows, from their astronomical studies, with slightly different results: The Hindu texts used the lunar cycle for setting months and days, but the solar cycle to set the complete year. This system is similar to the Jewish and Babylonian ancient calendars, creating

3904-528: The time it takes for a complete cycle of seasons ), traditionally used to facilitate the planning of agricultural activities. In a lunar calendar , the month approximates the cycle of the moon phase. Consecutive days may be grouped into other periods such as the week. Because the number of days in the tropical year is not a whole number, a solar calendar must have a different number of days in different years. This may be handled, for example, by adding an extra day in leap years . The same applies to months in

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3968-439: The year, which in reality is actually caused by the Earth revolving around the Sun. The rāśi s have 30° each and are named for constellations found in the zodiac. The time taken by the Sun to transit through a rāśi is a solar month whose name is identical to the name of the rāśi. In practice, solar months are mostly referred as rāśi (not months). The solar months are named differently in different regional calendars. While

4032-399: Was Greece, in 1923. The calendar epoch used by the Gregorian calendar is inherited from the medieval convention established by Dionysius Exiguus and associated with the Julian calendar. The year number is variously given as AD (for Anno Domini ) or CE (for Common Era or Christian Era ). The most important use of pre-modern calendars is keeping track of the liturgical year and

4096-421: Was introduced in 1582 as a refinement to the Julian calendar , that had been in use throughout the European Middle Ages, amounting to a 0.002% correction in the length of the year. During the Early Modern period, its adoption was mostly limited to Roman Catholic nations, but by the 19th century it had become widely adopted for the sake of convenience in international trade. The last European country to adopt it

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