Indian national calendar
The Indian national calendar, sometimes called the Shalivahana Shaka calendar. It is used, alongside the Gregorian calendar, by The Gazette of India, in news broadcasts by All India Radio and in calendars and communications issued by the Government of India; the Saka calendar is used in Java and Bali among Indonesian Hindus. Nyepi, the "Day of Silence", is a celebration of the Saka new year in Bali. Nepal's Nepal Sambat evolved from the Saka calendar. Prior to colonization, the Philippines used to apply the Saka calendar as well as suggested by the Laguna Copperplate Inscription; the term may ambiguously refer to the Hindu calendar. The historic Shalivahana era calendar is still used, it has years. The calendar months follow the signs of the tropical zodiac rather than the sidereal zodiac used with the Hindu calendar. Chaitra has 30 days and starts on March 22, except in leap years, when it has 31 days and starts on March 21; the months in the first half of the year all have 31 days, to take into account the slower movement of the sun across the ecliptic at this time.
The names of the months are derived from older, Hindu lunisolar calendars, so variations in spelling exist, there is a possible source of confusion as to what calendar a date belongs to. Years are counted in the Saka era. To determine leap years, add 78 to the Saka year – if the result is a leap year in the Gregorian calendar the Saka year is a leap year as well, its structure is just like the Persian calendar. Senior Indian Astrophysicist Meghnad Saha was the head of the Calendar Reform Committee under the aegis of the Council of Scientific and Industrial Research. Other members of the Committee were: A. C. Banerjee, K. K. Daftari, J. S. Karandikar, Gorakh Prasad, R. V. Vaidya and N. C. Lahiri, it was Saha's effort. The task before the Committee was to prepare an accurate calendar based on scientific study, which could be adopted uniformly throughout India, it was a mammoth task. The Committee had to undertake a detailed study of different calendars prevalent in different parts of the country. There were thirty different calendars.
The task was further complicated by the fact that religion and local sentiments were integral to those calendars. India's first prime minister, Jawaharlal Nehru, in his preface to the Report of the Committee, published in 1955, wrote: “They represent past political divisions in the country.... Now that we have attained Independence, it is desirable that there should be a certain uniformity in the calendar for our civic and other purposes, this should be done on a scientific approach to this problem.” Usage started at 1 Chaitra 1879, Saka Era, or 22 March 1957. Report of the Calendar Reform Committee – online link. Mapping Time: The Calendar and its History by E. G. Richards, 1998, pp. 184–185. Calendars and their History Indian Calendars Positional astronomy in India Indian National Calendar abstract
Nepal Sambat is the lunar calendar used by the Nepalese speaking people native to the Indian subcontinent of Nepalese nationality and ethnic Nepalis of Indian nationality. The Calendar era began on 20 October 879 AD, with the year 2013-14 AD corresponding to 1134 in Nepal Sambat. Nepal Sambat appeared on coins and copper plate inscriptions, royal decrees, chronicles and Buddhist manuscripts, legal documents and correspondence. Today, it is used for ceremonial purposes and to determine the dates of religious festivals and death anniversaries; the name Nepal Sambat was used for the calendar for the first time in Nepal Sambat 148. The Nepal Sambat epoch corresponds to 879 AD, which commemorates the payment of all the debts of the Nepalese people by a merchant named Sankhadhar Sakhwa in popular legend. According to the legend, an astrologer from Bhaktapur predicted that the sand at the confluence Bhacha Khushi and Bishnumati River in Kathmandu would transform into gold at a certain moment, so the king sent a team of workers to Kathmandu to collect sand from the spot at the special hour.
A local merchant named Sankhadhar Sakhwa saw them resting with their baskets of sand at a traveler's shelter at Maru near Durbar Square before returning to Bhaktapur. Believing that the sand to be unusual if the workers were gathering it, he convinced them to give it to him instead; the next day, Sakhwa discovered his sand had turned to gold, while the king of Bhaktapur was left with a pile of ordinary sand which his porters had dug up after the auspicious hour had passed. Sankhadhar used the gold to repay the debts of the Nepalese people. Nepal Sambat has been used outside Nepal Mandala in Nepal and in other countries including India and Myanmar. In Gorkha, a stone inscription at the Bhairav Temple at Pokharithok Bazaar contains the date Nepal Sambat 704. An inscription in the Khas language at a rest house in Salyankot is dated Nepal Sambat 912. In east Nepal, an inscription on the Bidyadhari Ajima Temple in Bhojpur recording the donation of a door and tympanum is dated Nepal Sambat 1011; the Bindhyabasini Temple in Bandipur in west Nepal contains an inscription dated Nepal Sambat 950 recording the donation of a tympanum.
The Palanchok Bhagawati Temple situated to the east of Kathmandu contains an inscription recording a land donation dated Nepal Sambat 861. An inscription on a stupa in Panauti is dated Nepal Sambat 866. Nepalese merchants based in Tibet used Nepal Sambat in their official documents and inscriptions recording votive offerings. A copper plate recording the donation of a tympanum at the shrine of Chhwaskamini Ajima in the Jokhang Temple in Lhasa is dated Nepal Sambat 781. Nepal Sambat was replaced as the national calendar in Rana period of the Kingdom of Nepal; the victory of the Gorkha Kingdom resulted in the end of the Malla dynasty and the advent of The Shahs used Saka era. However, Nepal Sambat remained in official use for a time after the coming of the Shahs. For example, the treaty with Tibet signed during the reign of Pratap Singh Shah is dated Nepal Sambat 895. In 1903, Saka Sambat, in turn, was superseded by Bikram Sambat as the official calendar. However, the government continued to use Saka Sambat on gold and silver coins till 1912 when it was replaced by Bikram Sambat.
The campaign to reinstate Nepal Sambat as the national calendar began in the 1920s when Dharmaditya Dharmacharya, a Buddhist and Nepal Bhasa activist based in Kolkata, initiated a campaign to promote it as the national calendar. The movement was continued by language and cultural activists in Nepal with the advent of democracy following the ouster of the autocratic Rana dynasty in 1951; the demand to make Nepal Sambat a national calendar intensified with the establishment of Nepal Bhasa Manka Khala in 1979. It organized rallies and public functions publicizing the importance of the era as a symbol of nationalism. Nepal Sambat has emerged as a symbol to rally people against the suppression of their culture and literature by the politically dominant ruling classes; the Panchayat regime suppressed the movement by imprisoning the activists. In 1987 in Kathmandu, a road running event organized to mark the New Year was broken up by police and the runners thrown in jail; the Nepal Sambat movement achieved its first success on 18 November 1999 when the government declared the founder of the calendar, a trader of Kathmandu named Sankhadhar Sakhwa, a national hero.
On 26 October 2003, the Department of Postal Service issued a commemorative postage stamp depicting his portrait. A statue of Sankhadhar was erected in Tansen, Palpa in western Nepal on 28 January 2012. On 25 October 2011, the government decided to bring Nepal Sambat into use as the country's national calendar following prolonged lobbying by cultural and social organizations, most prominently by Nepal Bhasa Manka Khala, formed a taskforce to make recommendations on its implementation. All major newspapers now print Nepal Sambat along with other dates on their mastheads. New Year's Day celebrations have spread from the Kathmandu Valley to other towns in Nepal as well as abroad. Nepal Sambat is a lunisolar calendar with 354 days in a normal year. An intercalary month named Anālā is added every three years to prevent the calendar from drifting with the seasons. New Year's Day falls on the first day of the waxing moon during the Swanti festival. Traditionally, traders used to close their ledgers and open new account books on the first day of Nepal Sambat.
Newars observe New Year's Day by performing Mha Puja, a ritual to purify and empower the soul for the coming New
The traditional China calendar, or Former Calendar, Traditional Calendar or Lunar Calendar, is a lunisolar calendar which reckons years and days according to astronomical phenomena. It is defined by GB/T 33661-2017, "Calculation and promulgation of the Chinese calendar", issued by the Standardisation Administration of China on 12 May 2017. Although modern day China uses the Gregorian calendar, the traditional Chinese calendar governs holidays in China and in overseas Chinese communities, it lists the dates of traditional Chinese holidays and guides people in selecting auspicious days for weddings, moving, or starting a business. Like Chinese characters, variants of this calendar are used in different parts of the Chinese cultural sphere. Korea and the Ryukyu Islands adopted the calendar, it evolved into Korean and Ryukyuan calendars; the main difference from the traditional Chinese calendar is the use of different meridians, which leads to some astronomical events—and calendar events based on them—falling on different dates.
The traditional Japanese calendar derived from the Chinese calendar, but its official use in Japan was abolished in 1873 as part of reforms after the Meiji Restoration. Calendars in Mongolia and Tibet have absorbed elements of the traditional Chinese calendar, but are not direct descendants of it. Days begin and end at midnight, months begin on the day of the new moon. Years begin on the second new moon after the winter solstice. Solar terms govern the end of each month. Written versions in ancient China included stems and branches of the year and the names of each month, including leap months as needed. Characters indicated whether a month was short; the traditional Chinese calendar was developed between 771 and 476 BC, during the Spring and Autumn period of the Eastern Zhou dynasty. Before the Zhou dynasty, solar calendars were used. One version of the solar calendar is the five-elements calendar. A 365-day year was divided into five phases of 73 days, with each phase corresponding to a Day 1 Wu Xing element.
A phase began followed by six 12-day weeks. Each phase consisted of two three-week months. Years began followed by a bǐngzǐ day and a 72-day fire phase. Other days were tracked using the Yellow River Map. Another version is a four-quarters calendar. Weeks were ten days long, with one month consisting of three weeks. A year had 12 months, with a ten-day week intercalated in summer as needed to keep up with the tropical year; the 10 Heavenly Stems and 12 Earthly Branches were used to mark days. A third version is the balanced calendar. A year was 365.25 days, a month was 29.5 days. After every 16th month, a half-month was intercalated. According to oracle bone records, the Shang dynasty calendar was a balanced calendar with 12 to 14 months in a year; the first lunisolar calendar was the Zhou calendar, introduced under the Zhou dynasty. This calendar set the beginning of the year at the day of the new moon before the winter solstice, it set the shàngyuán as the winter solstice of a dīngsì year, making the year it was introduced around 2,758,130.
Several competing lunisolar calendars were introduced by states fighting Zhou control during the Warring States period. The state of Lu issued its own Lu calendar. Jin issued the Xia calendar in AD 102, with a year beginning on the day of the new moon nearest the March equinox. Qin issued the Zhuanxu calendar, with a year beginning on the day of the new moon nearest the winter solstice. Song's Yin calendar began its year on the day of the new moon after the winter solstice; these calendars are known as the six ancient calendars, or quarter-remainder calendars, since all calculate a year as 365 1⁄4 days long. Months begin on the day of the new moon, a year has 12 or 13 months. Intercalary months are added to the end of the year; the Qiang and Dai calendars are modern versions of the Zhuanxu calendar, used by mountain peoples. After Qin Shi Huang unified China under the Qin dynasty in 221 BC, the Qin calendar was introduced, it followed most of the rules governing the Zhuanxu calendar, but the month order was that of the Xia calendar.
The intercalary month, known as the second Jiǔyuè, was placed at the end of the year. The Qin calendar was used into the Han dynasty. Emperor Wu of Han r. 141 – 87 BC introduced reforms halfway through his reign. His Taichu Calendar defined a solar year as 365 385⁄1539 days, the lunar month was 29 43⁄81 days; this calendar introduced the 24 solar terms. Solar terms were paired, with the 12 combined periods known as climate terms; the first solar term of the period was known as a pre-climate, the second was a mid-climate. Months were named for the mid-climat
The Javanese calendar is the calendar of the Javanese people. It is used concurrently with the Gregorian calendar and the Islamic calendar; the Gregorian calendar is the official calendar of the Republic of Indonesia and civil society, while the Islamic calendar is used by Muslims and the Indonesian government for religious worship and deciding relevant Islamic holidays. The Javanese calendar is used by the main ethnicities of Java island—that is, the Javanese and Sundanese people—primarily as a cultural icon and identifier, as a maintained tradition of antiquity; the Javanese calendar is used for cultural and spiritual purposes. The current system of the Javanese calendar was inaugurated by Sultan Agung of Mataram in the Gregorian year 1633 CE. Prior to this, the Javanese had used the Hindu calendar, which begins in 78 CE and uses the solar cycle for calculating time. Sultan Agung's calendar retained the Saka calendar year system of counting, but differs by using the same lunar year measurement system as the Islamic calendar, rather than the solar year.
The Javanese calendar is referred to by its Latin name Anno Javanico or AJ. The Javanese calendar contains multiple, overlapping measurements of times, called "cycles"; these include: the native five-day week, called Pasaran the common Gregorian and Islamic seven-day week the Solar month, called Mangsa the Lunar month, called Wulan the lunar year, or Tahun the octo-ennia cycles, or Windu the 120-year cycle of 15 Windu, called Kurup Days in the Javanese calendar, like the Islamic calendar, begin at sunset. Traditionally, Javanese people do not divide the night into hours, but rather into phases; the division of a day and night are: The native Javanese system groups days into a five-day week called Pasaran, unlike most calendars that uses a seven-day week. The name, pasaran, is derived from the root word pasar, but still today, Javanese villagers gather communally at local markets to meet, engage in commerce, buy and sell farm produce, cooked foods, home industry crafted items and so on. John Crawfurd suggested that the length of the weekly cycle is related to the number of fingers on the hand, that itinerant merchants would rotate their visits to different villages according to a five-day "roster".
The days of the cycle each have two names, as the Javanese language has distinct vocabulary associated with two different registers of politeness: ngoko and krama. The krama names for the days, second in the list, are much less common. ꦊꦒꦶ – ꦩꦤꦶꦱ꧀ ꦥꦲꦶꦁ – ꦥꦲꦶꦠ꧀ ꦥꦺꦴꦤ꧀ – ꦥꦼꦠꦏ꧀ ꦮꦒꦺ – ꦕꦼꦩꦺꦁ ꦏ꧀ꦭꦶꦮꦺꦴꦤ꧀ – ꦲꦱꦶꦃ The origin of the names is unclear, their etymology remains obscure. The names may be derived from indigenous gods, like the European and Asian names for days of the week. An ancient Javanese manuscript illustrates the week with five human figures: a man seizing a suppliant by the hair, a woman holding a horn to receive an offering, a man pointing a drawn sword at another, a woman holding agricultural produce, a man holding a spear leading a bull. Additionally, Javanese consider these days' names to have a mystical relation to colors and cardinal direction: Legi: white and East Pahing: red and South Pon: yellow and West Wage: black and North Kliwon: blurred colors/focus and'center'. Most Markets no longer operate under this traditional Pasaran cycle, instead pragmatically remaining open every day of the Gregorian week.
However many markets in Java still retain traditional names that indicated that once the markets only operated on certain Pasaran days, such as Pasar Legi, or Pasar Kliwon. Some markets in small or medium size locations will be much busier on the Pasaran day than on the other days. On the market's name day itinerate sellers appear selling such things as livestock and other products that are either less purchased or are more expensive; this allows a smaller number of these merchants to service a much larger area much as in bygone days. Javanese astrological belief dictates that an individual’s characteristics and destiny are attributable to the combination of the Pasaran day and the "common" weekday of the Islamic calendar on that person's birthday. Javanese people find great interest in the astrological interpretations of this combination, called the Wetonan cycle; the seven-day-long week cycle is derived from the Islamic calendar, adopted following the spread of Islam throughout the Indonesian archipelago.
The names of the days of the week in Javanese are derived from their Arabic counterparts, namely: These two-week systems occur concurrently. This combination forms the Wetonan cycle; the Wetonan cycle superimposes the five-day Pasaran cycle with the seven-day week cycle. Each Wetonan cycle lasts for 35 days. An example of Wetonan cycle: From the example above, the Weton for Tuesday May 6, 2008 would be read as Selasa Wage; the Wetonan cycle is important for divinatory systems, important celebrations, rites of passage. Commemorations and events are held on days considered to be auspicious. An prominent example, still taught in primary schools, is that the Weton for the Proclamation of Indonesian Independence on 17 August 1945 took place on Jumat Legi. Therefore, Jumat Legi is considered an important night for pilgrimage. There are taboos
Mongolia is a landlocked country in East Asia. Its area is equivalent with the historical territory of Outer Mongolia, that term is sometimes used to refer to the current state, it is sandwiched between China to Russia to the north. Mongolia does not share a border with Kazakhstan. At 1,564,116 square kilometres, Mongolia is the 18th-largest and the most sparsely populated sovereign state in the world, with a population of around three million people, it is the world's second-largest landlocked country behind Kazakhstan and the largest landlocked country that does not border a closed sea. The country contains little arable land, as much of its area is covered by grassy steppe, with mountains to the north and west and the Gobi Desert to the south. Ulaanbaatar, the capital and largest city, is home to about 45% of the country's population. Ulaanbaatar shares the rank of the world's coldest capital city with Moscow and Nur-Sultan. 30% of the population is nomadic or semi-nomadic. The majority of its population are Buddhists.
The non-religious population is the second largest group. Islam is the dominant religion among ethnic Kazakhs; the majority of the state's citizens are of Mongol ethnicity, although Kazakhs and other minorities live in the country in the west. Mongolia joined the World Trade Organization in 1997 and seeks to expand its participation in regional economic and trade groups; the area of what is now Mongolia has been ruled by various nomadic empires, including the Xiongnu, the Xianbei, the Rouran, the Turkic Khaganate, others. In 1206, Genghis Khan founded the Mongol Empire, which became the largest contiguous land empire in history, his grandson Kublai Khan conquered China to establish the Yuan dynasty. After the collapse of the Yuan, the Mongols retreated to Mongolia and resumed their earlier pattern of factional conflict, except during the era of Dayan Khan and Tumen Zasagt Khan. In the 16th century, Tibetan Buddhism began to spread in Mongolia, being further led by the Manchu-founded Qing dynasty, which absorbed the country in the 17th century.
By the early 1900s one-third of the adult male population were Buddhist monks. After the collapse of the Qing dynasty in 1911, Mongolia declared independence, achieved actual independence from the Republic of China in 1921. Shortly thereafter, the country came under the control of the Soviet Union, which had aided its independence from China. In 1924, the Mongolian People's Republic was founded as a socialist state. After the anti-Communist revolutions of 1989, Mongolia conducted its own peaceful democratic revolution in early 1990; this led to a multi-party system, a new constitution of 1992, transition to a market economy. Homo erectus inhabited Mongolia from 850,000 years ago. Modern humans reached Mongolia 40,000 years ago during the Upper Paleolithic; the Khoit Tsenkher Cave in Khovd Province shows lively pink and red ochre paintings of mammoths, bactrian camels, ostriches, earning it the nickname "the Lascaux of Mongolia". The venus figurines of Mal'ta testify to the level of Upper Paleolithic art in northern Mongolia.
Neolithic agricultural settlements, such as those at Norovlin, Tamsagbulag and Rashaan Khad, predated the introduction of horse-riding nomadism, a pivotal event in the history of Mongolia which became the dominant culture. Horse-riding nomadism has been documented by archeological evidence in Mongolia during the Copper and Bronze Age Afanasevo culture; the wheeled vehicles found in the burials of the Afanasevans have been dated to before 2200 BC. Pastoral nomadism and metalworking became more developed with the Okunev culture, Andronovo culture and Karasuk culture, culminating with the Iron Age Xiongnu Empire in 209 BC. Monuments of the pre-Xiongnu Bronze Age include deer stones, keregsur kurgans, square slab tombs, rock paintings. Although cultivation of crops has continued since the Neolithic, agriculture has always remained small in scale compared to pastoral nomadism. Agriculture arose independently in the region; the population during the Copper Age has been described as mongoloid in the east of what is now Mongolia, as europoid in the west.
Tocharians and Scythians inhabited western Mongolia during the Bronze Age. The mummy of a Scythian warrior, believed to be about 2,500 years old, was a 30- to 40-year-old man with blond hair; as equine nomadism was introduced into Mongolia, the political center of the Eurasian Steppe shifted to Mongolia, where it remained until the 18th century CE. The intrusions of northern pastoralists into China during the Shang dynasty and Zhou dynasty presaged the age of nomadic empires; the concept of Mongolia as an independent power north of China is expressed in a letter sent by Emperor Wen of Han to Laoshang Chanyu in 162 BC: Since prehistoric times, Mongolia has been inhabited by nomads who, from time to time, formed great confederations that rose to power and prominence. Common institutions were the office of the Khan, the Kurultai and right wings, imperial army and the decimal military system; the first of these empires, the Xiongnu of undetermined
Adherents of Zoroastrianism use three distinct versions of traditional calendars for liturgical purposes, all derived from medieval Iranian calendars based on the Babylonian calendar as used in the Achaemenid empire. "Qadimi" is a traditional reckoning introduced in 1006. "Shahanshahi" is a calendar. "Fasli" is a term for a 1906 adaptation of the 11th-century Jalali calendar, following a proposal by Kharshedji Rustomji Cama made in the 1860s. A number of Calendar eras are in use: A tradition of counting years from the birth of Zoroaster was reported from India in the 19th century. There was a dispute between factions variously preferring an era of 389 BCE, 538 BCE or 637 BCE; the "Yazdegerdi era" counts from the accession of the last Sassanid ruler, Yazdegerd III. This convention was proposed by Cama in the 1860s but has since been used in conjunctions with "Qadimi" or "Shahanshahi" reckoning. An alternative "Magian era" was set at the date of Yazdegerd's death, in 652. "Z. E. R." or "Zarathushtrian Religious Era" is a convention introduced in 1990 by the "Zarathushtrian Assembly of California", set at vernal equinox of 1737 BCE.
The Babylonian calendar was used in the Achaemenid Empire by the 4th century BCE for civil purposes. The earliest Zoroastrian calendar follows the Babylonian in relating the seventh and other days of the month to Ahura Mazda. Like all ancient calendar, the Babylonian calendar was lunisolar, it used an intercalary month once every six years. In the civil calendar, intercalations did not always follow a regular pattern, but during the reign of Artaxerxes II astronomers utilised a 19 year cycle which required the addition of a month called Addaru II in years 3, 6, 8, 11, 14 and 19, the month Ululu II in year 17 of the cycle; the first known intercalation is recorded for 309 BCE. The first month of the year was called Frawardin, the first day of Frawardin was the'New Year's Day' or Nawruz, from which all other religious observances were reckoned – this day being, in theory, the day of the northern vernal equinox. A 365 day calendar, with months identical to the Egyptian calendar, was introduced shortly after the conquest of Egypt by the Achaemenid ruler Cambyses.
Scholars are divided on whether this 365 day calendar was in fact preceded by a 360 day calendar of Zoroastrian observances. Following Alexander's conquest of Persia in 330 BCE, the Seleucids instituted the Hellenic practice of counting years from the start of a fixed era, as opposed using regnal years; the regnal era of Alexander is now referred to as the Seleucid era. The Parthians, who succeeded the Seleucids, continued the Seleucid/Hellenic tradition. In 224 CE, when the Babylonian calendar was replaced by the Zoroastrian, 1 Frawardin and the New Year celebration of Nawruz had drifted to 1 October; the older custom of counting regnal years from the monarch's coronation was reinstated. At this point the calendar was realigned with the seasons by delaying the epagemonai by eight months and adjusting the dates of the gahanbar accordingly; this caused confusion, since the new year now fell five days earlier than before, some people continued to observe the old date. After 46 years, with 1 Frawardin now on 19 September, another calendar reform was implemented by Ardashir's grandson Hormazd I.
During the first years after implementation of the new Gatha days, the population had not universally adopted the new dates for religious festivals, resulting in "official" celebrations takings place five days earlier than popular celebrations. In years the population had observed the Gatha days, but the original five day discrepancy persisted. Hormazd's reform was to link the popular and official observance dates to form continual six-day feasts. Nawruz was an exception: the first and the sixth days of the month were celebrated as different occasions. Lesser Nawruz was observed on 1 Frawardin. 6 Frawardin became a day of special festivity. Around the 10th century CE, the Greater Nawruz was associated with the return of the legendary king, Jamsed. Mary Boyce has argued that sometime between 399 CE and 518 CE the six-day festivals were compressed to five days; the major feasts, or gahambars, of contemporary Zoroastrian practice, are still kept as five-day observances today. The Bundahishn, a pseudo-Avestan treatise written in the early Islamic period replaces the "Age of Alexander" with an "Ageo of Zoroaster", placed "258 years before Alexander".
By the reign of Yazdegird III, the religious celebrations were again somewhat adrift with respect to their proper seasons. The calendar had continued to slip against the Julian calendar since the previous reform at the rate of one day every four years. Therefore, in 632, the new year was celebrated on 16 June. By the 9th century, the Zoroastrian theologian Zadspram had noted that the state of affairs was less than optimal, estimated that at the time of Final Judgement the two systems would be out of sync by four years; the current mainstream Zoroastrian reckoning of years’ start date is on 16 June 632 CE. Yazdegird III was the last monarch of the Sasanian dynasty, since the custom at that time was to count regnal years since the monarch ascended the throne, the reckoning of years was continued, in the absence of a Zoroastrian monarch, under Islamic rule. Zo
In astronomy, the new moon is the first lunar phase, when the Moon and Sun have the same ecliptic longitude. At this phase, the lunar disk is not visible to the unaided eye, except when silhouetted during a solar eclipse. Daylight outshines the earthlight; the actual phase is a thin crescent. The original meaning of the term new moon, still sometimes used in non-astronomical contexts, was the first visible crescent of the Moon, after conjunction with the Sun; this crescent moon is visible when low above the western horizon shortly after sunset and before moonset. A lunation or synodic month is the average time from one new moon to the next. In the J2000.0 epoch, the average length of a lunation is 29.530588 days. However, the length of any one synodic month can vary from 29.26 to 29.80 days due to the perturbing effects of the Sun's gravity on the Moon's eccentric orbit. In a lunar calendar, each month corresponds to a lunation; each lunar cycle can be assigned a unique lunation number to identify it.
The length of a lunation is about 29.53 days. Its precise duration is linked to many phenomena in nature, such as the variation between spring and neap tides. An approximate formula to compute the mean moments of new moon for successive months is: d = 5.597661 + 29.5305888610 × N + × N 2 where N is an integer, starting with 0 for the first new moon in the year 2000, and, incremented by 1 for each successive synodic month. To obtain this moment expressed in Universal Time, add the result of following approximate correction to the result d obtained above: − 0.000739 − × N 2 daysPeriodic perturbations change the time of true conjunction from these mean values. For all new moons between 1601 and 2401, the maximum difference is 0.592 days = 14h13m in either direction. The duration of a lunation varies in this period between 29.272 and 29.833 days, i.e. −0.259d = 6h12m shorter, or +0.302d = 7h15m longer than average. This range is smaller than the difference between mean and true conjunction, because during one lunation the periodic terms cannot all change to their maximum opposite value.
See the article on the full moon cycle for a simple method to compute the moment of new moon more accurately. The long-term error of the formula is approximately: 1 cy2 seconds in TT, 11 cy2 seconds in UT The moment of mean conjunction can be computed from an expression for the mean ecliptical longitude of the Moon minus the mean ecliptical longitude of the Sun. Jean Meeus gave formulae to compute this in his Astronomical Formulae for Calculators based on the ephemerides of Brown and Newcomb; these are now outdated: Chapront et al. published improved parameters. Meeus's formula uses a fractional variable to allow computation of the four main phases, uses a second variable for the secular terms. For the convenience of the reader, the formula given above is based on Chapront's latest parameters and expressed with a single integer variable, the following additional terms have been added: constant term: Like Meeus, apply the constant terms of the aberration of light for the Sun's motion and light-time correction for the Moon to obtain the apparent difference in ecliptical longitudes:Sun: +20.496" Moon: −0.704" Correction in conjunction: −0.000451 daysFor UT: at 1 January 2000, ΔT was +63.83 s.
The term includes a tidal contribution of 0.5×. The most current estimate from Lunar Laser Ranging for the acceleration is:"/cy2. Therefore, the new quadratic term of D is = -6.8498"T2. Indeed, the polynomial provided by Chapront et alii provides the same value; this translates to a correction of +14.622×10−12N2 days to the time of conjunction. For UT: analysis of historical observations shows that ΔT has a long-term increase of +31 s/cy2. Converted to days and lunations, the correction from ET to UT becomes:−235×10−12N2 days; the theoretical tidal contribution to ΔT is about +42 s/cy2 the smaller observed value is thought to be due to changes in the shape of the Earth. Because the discrepancy is not explained, uncertainty of our prediction of UT may be as large as the difference between these values: 11 s/cy2; the error in the position of the Moon itself is only maybe 0.5"/cy2, or (because the apparent mean angular velocit