Chinese calendar

Lunisolar calendar from China
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Chinese calendar
Traditional Chinese農曆
Simplified Chinese农历
Transcriptions
Standard Mandarin
Hanyu Pinyinnónglì
Bopomofoㄋㄨㄥˊ ㄌㄧˋ
Wade–Gilesnung2 li4
Tongyong Pinyinnóng-lì
IPA[nʊ̌ŋ.lî]
Yue: Cantonese
Jyutpingnung4 lik6
IPA[noŋ˩ lek̚˨]
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The traditional Chinese calendar (traditional Chinese: 農曆; simplified Chinese: 农历; lit. 'agricultural calendar'; informally traditional Chinese: 陰曆; simplified Chinese: 阴历; lit. 'lunar calendar') is a lunisolar calendar, combining the solar, lunar, and other cycles for various social and agricultural purposes. More recently, in China and Chinese communities the Gregorian calendar has been adopted and adapted in various ways, and is generally the basis for standard civic purposes, though also incorporating traditional lunisolar holidays. Also, there are many types and subtypes of the Chinese calendar, partly reflecting developments in astronomical observation and horology, with over a millennium plus history. The major modern form is the Gregorian calendar-based official version of the Mainland China, though diaspora versions are also notable in other parts of China and Chinese-influenced cultures; however, aspects of the traditional lunisolar calendar remain popular, including the association of the twelve animals of the Chinese Zodiac in relation to months and years.

The traditional calendar calendars used the sexagenary cycle-based ganzhi system's mathematically repeating cycles of Heavenly Stems and Earthly Branches. Together with astronomical, horological, and phenologic observations, definitions, measurements, and predictions of years, months, and days were refined. Astronomical phenomena and calculations emphasized especially the efforts to mathematically correlate the solar and lunar cycles from the perspective of the earth, which however are known to require some degree of numeric approximation or compromise.

The logic of the various permutations of the Chinese calendar has been based in considerations such as the technical from mathematics and astronomy, the philosophical considerations, and the political, and the resulting disparities between different calendars is significantly notable. Various similar calendar systems are also known from various regions or ethnic groups of Central Asia, South Asia, and other areas. Indeed, the Chinese calendar has influenced and been influenced by most parts of the world these days. One particularly popular feature is the Chinese zodiac. The Chinese calendar and horology includes many multifaceted methods of computing years, eras, months, days and hours (with modern horology even splitting the seconds into very tiny sub-units using atomic methods).

Epochs are one of the important features of calendar systems. An epoch is a particular point in time at which a calendar system may use as its initial time reference, allowing for the consecutive numbering of years from a chosen starting year, date, or time. In the Chinese calendar system, examples include the inauguration of Huangdi or the birth of Confucius. Also, many dynasties had their own dating systems, which could include regnal eras based on the inauguration of a dynasty, the enthronement of a particular monarch, or eras arbitrarily designated due to political or other considerations, such as a desire for a change of luck. Era names are useful for determining dates on artifacts such as ceramics, which were often traditionally dated by an era name during the production process.

Historical variations of the lunisolar calendar are features of the Chinese calendar system. The topic of the Chinese calendar includes various traditional types of the Chinese calendar. As is generally the case with calendar systems, the Chinese calendars tend to focus on basic calendar functions, such as the identification of years, months, and days according to astronomical phenomena and calculations, with a special effort to correlate the solar and lunar cycles experienced on earth—an effort which is known to mathematically require some degree of approximation. One of the major features of some traditional calendar systems in China (and elsewhere) has been the idea of the sexagenary cycle. The Chinese lunisolar calendar has had several significant variations over the course of time and history. Many historical variations in the Chinese calendar are associated with political changes, such as dynastic succession. Solar and agricultural calendars have a long history in China. Purely lunar calendar systems were known in China; however, purely lunar calendars tended to be of limited utility, and were not widely accepted by farmers, who for agricultural purposes needed to focus on predictability of seasons for planting and harvesting purposes, and thus required a calendar useful for agricultural. For farming purposes and keeping track of the seasons Chinese solar or lunisolar calendars were particularly useful. Thus, over time, the publication of multipurpose and agricultural almanacs has become a longstanding tradition in China

Various other astronomical phenomena have been incorporated into calendars besides the cycles of the sun and the moon, for example, the planets and the constellations (or mansions) of asterisms along the ecliptic.

Many Chinese holidays and other areas both in ancient and modern times have been determined by the traditional lunisolar calendar or considerations based upon the lunisolar calendar; and, which now are generally combined with more modern calendar considerations. The traditions of the lunisolar calendar remain very popular and the Gregorian calendar has been used as the standard basis for civic calendars.

Etymology

The name of calendar is in Chinese: 曆; pinyin: lì, and was represented in earlier character forms variants (歷, 厤), and ultimately derived from an ancient form (秝). The ancient form of the character consists of two stalks of rice plant (禾), arranged in parallel. This character represents the order in space and also the order in time.[1] As its meaning became complex, the modern dedicated character (曆) was created to represent the meaning of calendar.

Maintaining the correctness of calendars was an important task to maintain the authority of rulers. It showed the ability of a ruler. For example, a ruler should foresee the coming of seasons and prepared for it. A ruler should predict the abnormalities of the earth and sky such as lunar and solar eclipses. This is why there are 102 calendars in Chinese history, trying to predict the correct courses of sun, moon and stars, and marking good time and bad time. Each calendar is named as XX曆 and recorded in a dedicated calendar section in history books of different eras. The last one in imperial era was 時憲曆. A ruler would issue an almanac before the commencement of each year. There were private almanac issuers, usually illegal, when a ruler lost his control to some territories.

Various modern Chinese calendar names resulted due of the struggle between the introduction of Gregorian calendar by government and the preservation of customs by the public in the era of Republic of China.[2] The government wanted to abolish the Chinese calendar to force everyone to use the Gregorian calendar, and even abolished the Lunar New Year, but faced great opposition. The public needed the astronomical Chinese calendar to do things at a proper time, for example farming and fishing; also, a wide spectrum of festivals and customs observations have been based on the calendar. The government finally compromised and rebranded it as the agricultural calendar in 1947,[3] depreciating the calendar to merely agricultural use.

Some modern names of Chinese calendar and Gregorian calendar
Chinese calendar Gregorian calendar
唐曆, 華曆, Chinese calendar 西洋曆, 洋曆, 西曆, Western calendar
舊曆, 老曆, 古曆, old calendar 新曆, new calendar
陰曆, lunar calendar 陽曆, solar calendar
傳統曆, traditional calendar
農曆, 農民曆, agricultural calendar
夏曆, The first dynasty calendar
黄曆, 黄帝曆, Yellow Emperor calendar
公曆, public calendar, namely universal calendar or common calendar
國曆, national calendar
皇曆, Imperial calendar (obsoleted)

After the end of the imperial era, there are some almanacs based upon the algorithm of the last Imperial calendar with longitude of Peking. Such almanacs were under the name of "universal book" 通書, or under Cantonese name 通勝, transcribed as Tung Shing. And later these almanacs moved to new calculation based on the location of Purple Mountain Observatory, with longitude of 120°E.

Epochs

An epoch is a point in time chosen as the origin of a particular calendar era, thus serving as a reference point from which subsequent time or dates are measured. The use of epochs in Chinese calendar system allow for a chronological starting point from whence to begin point continuously numbering subsequent dates. Various epochs have been used. Similarly, nomenclature similar to that of the Christian era has occasionally been used:[4]

Era Chinese name Start Year 1 2024 CE is year...
Yellow Emperor (Huángdì) year 黄帝紀年 Yellow Emperor (YE) began reigning 2697 BCE or 2698 BCE 4721 or 4722
Yáo year 唐堯紀年 Emperor Yao began reigning 2156 BCE 4180
Gònghé year 共和紀年 Gonghe Regency began 841 BCE 2865
Confucius year 孔子紀年 Confucius's birth year 551 BCE 2575
Unity year 統一紀年 Qin Shi Huang began reigning 221 BCE 2245

No reference date is universally accepted. The most popular is the Gregorian calendar (公曆; 公历; gōnglì; 'common calendar').

During the 17th century, the Jesuit missionaries tried to determine the epochal year of the Chinese calendar. In his Sinicae historiae decas prima (published in Munich in 1658), Martino Martini (1614–1661) dated the Yellow Emperor's ascension at 2697 BCE and began the Chinese calendar with the reign of Fuxi (which, according to Martini, began in 2952 BCE). Philippe Couplet's 1686 Chronological table of Chinese monarchs (Tabula chronologica monarchiae sinicae) gave the same date for the Yellow Emperor. The Jesuits' dates provoked interest in Europe, where they were used for comparison with Biblical chronology.[citation needed] Modern Chinese chronology has generally accepted Martini's dates, except that it usually places the reign of the Yellow Emperor at 2698 BCE and omits his predecessors Fuxi and Shennong as "too legendary to include".[This quote needs a citation]

Publications began using the estimated birth date of the Yellow Emperor as the first year of the Han calendar in 1903, with newspapers and magazines proposing different dates. Jiangsu province counted 1905 as the year 4396 (using a year 1 of 2491 BCE, and implying that 2024 CE is 4515), and the newspaper Ming Pao (明報) reckoned 1905 as 4603 (using a year 1 of 2698 BCE, and implying that 2024 CE is 4722).[citation needed] Liu Shipei (劉師培, 1884–1919) created the Yellow Emperor Calendar (黃帝紀元, 黃帝曆 or 軒轅紀年), with year 1 as the birth of the emperor (which he determined as 2711 BCE, implying that 2024 CE is 4735).[5] There is no evidence that this calendar was used before the 20th century.[6] Liu calculated that the 1900 international expedition sent by the Eight-Nation Alliance to suppress the Boxer Rebellion entered Beijing in the 4611th year of the Yellow Emperor.

Taoists later adopted Yellow Emperor Calendar and named it Tao Calendar (道曆).

On 2 January 1912, Sun Yat-sen announced changes to the official calendar and era. 1 January was 14 Shíyīyuè 4609 Huángdì year, assuming a year 1 of 2698 BCE, making 2024 CE year 4722. Many overseas Chinese communities like San Francisco's Chinatown adopted the change.[7]

The modern Chinese standard calendar uses the epoch of the Gregorian calendar, which is on 1 January of the year 1 CE.

Calendar types

Lunisolar

Lunisolar calendars involve correlations of the cycles of the sun (solar) and the moon (lunar).

Solar and agricultural

A solar calendar keeps track of the seasons as the earth and the sun move in the solar system relatively to each other. A purely solar calendar may be useful in planning times for agricultural activities such as planting and harvesting. Solar calendars tend to use astronomically observable points of reference such as equinoxes and solstices, events which may be approximately predicted using fundamental methods of observation and basic mathematical analysis.

Modern Chinese calendar and horology

The topic of the Chinese calendar also includes variations of the modern Chinese calendar, influenced by the Gregorian calendar. Variations include methodologies of the People's Republic of China and Taiwan.

Modern calendars

In China, the modern calendar is defined by the Chinese national standard GB/T 33661–2017,[8] "Calculation and Promulgation of the Chinese Calendar", issued by the Standardization Administration of China on 12 May 2017.

Influence of Gregorian calendar

Although modern-day China uses the Gregorian calendar, the traditional Chinese calendar governs holidays, such as the Chinese New Year and Lantern Festival, in both China and overseas Chinese communities. It also provides the traditional Chinese nomenclature of dates within a year which people use to select auspicious days for weddings, funerals, moving or starting a business.[9] The evening state-run news program Xinwen Lianbo in the People's Republic of China continues to announce the months and dates in both the Gregorian and the traditional lunisolar calendar.

History

The Chinese calendar system has a long history, which has traditionally been associated with specific dynastic periods. Various individual calendar types have been developed with different names. In terms of historical development, some of the calendar variations are associated with dynastic changes along a spectrum beginning with a prehistorical/mythological time to and through well attested historical dynastic periods. Many individuals have been associated with the development of the Chinese calendar, including researchers into underlying astronomy; and, furthermore, the development of instruments of observation are historically important. Influences from India, Islam, and Jesuits also became significant.

Phenology

Early calendar systems often were closely tied to natural phenomena. Phenology is the study of periodic events in biological life cycles and how these are influenced by seasonal and interannual variations in climate, as well as habitat factors (such as elevation).[10] The plum-rains season (梅雨), the rainy season in late spring and early summer, begins on the first bǐng day after Mangzhong (芒種) and ends on the first wèi day after Xiaoshu (小暑). The Three Fu (三伏; sānfú) are three periods of hot weather, counted from the first gēng day after the summer solstice. The first fu (初伏; chūfú) is 10 days long. The mid-fu (中伏; zhōngfú) is 10 or 20 days long. The last fu (末伏; mòfú) is 10 days from the first gēng day after the beginning of autumn.[11] The Shujiu cold days (數九; shǔjǐu; 'counting to nine') are the 81 days after the winter solstice (divided into nine sets of nine days), and are considered the coldest days of the year. Each nine-day unit is known by its order in the set, followed by "nine" (九).[12] In traditional Chinese culture, "nine" represents the infinity, which is also the number of "Yang". According to one belief nine times accumulation of "Yang" gradually reduces the "Yin", and finally the weather becomes warm.[13]

Names of months

Lunar months were originally named according to natural phenomena. Current naming conventions use numbers as the month names. Every month is also associated with one of the twelve Earthly Branches.

Month number Starts on Gregorian date Phenological name Earthly Branch name Modern name
1 between 21 January – 20 February * 陬月; zōuyuè; 'corner month'. square of Pegasus month 寅月; yínyuè; 'tiger month' 正月; zhēngyuè; 'first month'
2 between 20 February – 21 March * 杏月; xìngyuè; 'apricot month' 卯月; mǎoyuè; 'rabbit month' 二月; èryuè; 'second month'
3 between 21 March – 20 April * 桃月; táoyuè; 'peach month' 辰月; chényuè; 'dragon month' 三月; sānyuè; 'third month'
4 between 20 April – 21 May * 梅月; méiyuè; 'plum month' 巳月; sìyuè; 'snake month' 四月; sìyuè; 'fourth month'
5 between 21 May – 21 June * 榴月; liúyuè; 'pomegranate month' 午月; wǔyuè; 'horse month' 五月; wǔyuè; 'fifth month'
6 between 21 June – 23 July * 荷月; héyuè; 'lotus month' 未月; wèiyuè; 'goat month' 六月; liùyuè; 'sixth month'
7 between 23 July – 23 August * 蘭月; 兰月; lányuè; 'orchid month' 申月; shēnyuè; 'monkey month' 七月; qīyuè; 'seventh month'
8 between 23 August – 23 September * 桂月; guìyuè; 'osmanthus month' 酉月; yǒuyuè; 'rooster month' 八月; bāyuè; 'eighth month'
9 between 23 September – 23 October * 菊月; júyuè; 'chrysanthemum month' 戌月; xūyuè; 'dog month' 九月; jiǔyuè; 'ninth month'
10 between 23 October – 22 November * 露月; lùyuè; 'dew month' 亥月; hàiyuè; 'pig month' 十月; shíyuè; 'tenth month'
11 between 22 November – 22 December * 冬月; dōngyuè; 'winter month'; 葭月; jiāyuè; 'reed month' 子月; zǐyuè; 'rat month' 十一月; 'eleventh month' or 冬月; dōngyuè; 'eleventh month'
12 between 22 December – 21 January * 冰月; bīngyuè; 'ice month' 丑月; chǒuyuè; 'ox month' 十二月; 'twelfth month' or 臘月; 腊月; làyuè; 'end-of-year month'

Chinese astronomy

The Chinese calendar has been a development involving much observation and calculation of the apparent movements of the Sun, Moon, planets, and stars, as observed from Earth.

Chinese astronomers

Many Chinese astronomers have contributed to the development of the Chinese calendar. Many were of the scholarly or shi class (Chinese: 士; pinyin: shì), including writers of history, such as Sima Qian.

Notable Chinese astronomers who have contributed to the development of the calendar include Gan De, Shi Shen, and Zu Chongzhi

Technology

Early technological developments aiding in calendar development include the development of the gnomon. Later technological developments useful to the calendar system include naming, numbering and mapping of the sky, the development of analog computational devices such as the armillary sphere and the water clock, and the establishment of observatories.

Chinese calendar names

Ancient six calendars

From the Warring States period (ending in 221 BCE), six especially significant calendar systems are known to have begun to be developed. Later on, during their future course in history, the modern names for the ancient six calendars were also developed, and can be translated into English as Huangdi, Yin, Zhou, Xia, Zhuanxu, and Lu.[14]

Calendar variations

There are various Chinese terms for calendar variations including:

Handwritten calendar
Page of a Chinese calendar containing monthly information in the years Daoguang 14–16, corresponding to 1834–1836

Solar calendars

See caption
Five-phase and four-quarter calendars

The traditional Chinese calendar was developed between 771 BCE and 476 BCE, during the Spring and Autumn period of the Eastern Zhou dynasty. Solar calendars were used before the Zhou dynasty period, along with the basic sexagenary system.

Five-elements calendar

One version of the solar calendar is the five-elements calendar (五行曆; 五行历), which derives from the Wu Xing. 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 with a governing-element day (行御), followed by six 12-day weeks. Each phase consisted of two three-week months, making each year ten months long. Years began on a jiǎzǐ (甲子) day (and a 72-day wood phase), followed by a bǐngzǐ day (丙子) and a 72-day fire phase; a wùzǐ (戊子) day and a 72-day earth phase; a gēngzǐ (庚子) day and a 72-day metal phase, and a rénzǐ day (壬子) followed by a water phase.[15] Other days were tracked using the Yellow River Map (He Tu).

Four-quarters calendar

Another version is a four-quarters calendar (四時八節曆; 四时八节历; 'four sections', 'eight seasons calendar', or 四分曆; 四分历). The 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.[16]

Balanced calendar

A third version is the balanced calendar (調曆; 调历). A year was 365.25 days, and a month was 29.5 days. After every 16th month, a half-month was intercalated. According to oracle bone records, the Shang dynasty calendar (c. 1600 – c. 1046 BCE) was a balanced calendar with 12 to 14 months in a year; the month after the winter solstice was Zhēngyuè.[17]

Lunisolar calendars by dynasty

Six ancient calendars

Modern historical knowledge and records are limited for the earlier calendars. These calendars are known as the six ancient calendars (古六曆; 古六历), or quarter-remainder calendars, (四分曆; 四分历; sìfēnlì), since all calculate a year as 365+1⁄4 days long. Months begin on the day of the new moon, and a year has 12 or 13 months. Intercalary months (a 13th month) are added to the end of the year. The Qiang and Dai calendars are modern versions of the Zhuanxu calendar, used by mountain peoples.

Zhou dynasty

The first lunisolar calendar was the Zhou calendar (周曆; 周历), introduced under the Zhou dynasty (1046 BCE – 256 BCE). This calendar sets the beginning of the year at the day of the new moon before the winter solstice.

Competing Warring states calendars

Several competing lunisolar calendars were also introduced as Zhou devolved into the Warring States, especially by states fighting Zhou control during the Warring States period (perhaps 475 BCE - 221 BCE). The state of Lu issued its own Lu calendar(魯曆; 鲁历). Jin issued the Xia calendar (夏曆; 夏历)[18] with a year beginning on the day of the new moon nearest the March equinox. Qin issued the Zhuanxu calendar (顓頊曆; 颛顼历), with a year beginning on the day of the new moon nearest the winter solstice. Song's Yin calendar (殷曆; 殷历) began its year on the day of the new moon after the winter solstice.

Qin and early Han dynasties

After Qin Shi Huang unified China under the Qin dynasty in 221 BCE, the Qin calendar (秦曆; 秦历) was introduced. It followed most of the rules governing the Zhuanxu calendar, but the month order was that of the Xia calendar; the year began with month 10 and ended with month 9, analogous to a Gregorian calendar beginning in October and ending in September. The intercalary month, known as the second Jiǔyuè (後九月; 后九月; 'later Jiǔyuè'), was placed at the end of the year. The Qin calendar was used going into the Han dynasty.

Han dynasty Tàichū calendar

Emperor Wu of Han r. 141 – 87 BCE introduced reforms in the seventh of the eleven named eras of his reign, Tàichū (Chinese: 太初; pinyin: Tàichū; lit. 'Grand Beginning'), 104 BCE – 101 BCE. His Tàichū Calendar (太初曆; 太初历; 'grand beginning calendar') defined a solar year as 365+385⁄1539 days (365;06:00:14.035), and the lunar month had 29+43⁄81 days (29;12:44:44.444). Since ( 365 + 385 1539 ) × 19 = ( 29 + 43 81 ) × ( 19 × 12 + 7 ) {\displaystyle \left(365+{\frac {385}{1539}}\right)\times 19=\left(29+{\frac {43}{81}}\right)\times \left(19\times 12+7\right)} the 19 years cycle used for the 7 additional months was taken as an exact one, and not as an approximation.

This calendar introduced the 24 solar terms, dividing the year into 24 equal parts of 15° each. 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 (节气), and the second was a mid-climate (中气). Months were named for the mid-climate to which they were closest, and a month without a mid-climate was an intercalary month.[citation needed]

The Taichu calendar established a framework for traditional calendars, with later calendars adding to the basic formula.

Northern and Southern Dynasties Dàmíng calendar

The Dàmíng Calendar (大明曆; 大明历; 'brightest calendar'), created in the Northern and Southern Dynasties by Zu Chongzhi (429 CE – 500 CE), introduced the equinoxes.

Tang dynasty Wùyín Yuán calendar

The use of syzygy to determine the lunar month was first described in the Tang dynasty Wùyín Yuán Calendar (戊寅元曆; 戊寅元历; 'earth tiger epoch calendar').

Yuan dynasty Shòushí calendar

The Yuan dynasty Shòushí calendar (授時曆; 授时历; 'season granting calendar') used spherical trigonometry to find the length of the tropical year.[19][20][21] The calendar had a 365.2425-day year, identical to the Gregorian calendar.[22]

Although the Chinese calendar lost its place as the country's official calendar at the beginning of the 20th century,[23] its use has continued. The Republic of China Calendar published by the Beiyang government of the Republic of China still listed the dates of the Chinese calendar in addition to the Gregorian calendar. In 1929, the Nationalist government tried to ban the traditional Chinese calendar. The Kuómín Calendar published by the government no longer listed the dates of the Chinese calendar. However, Chinese people were used to the traditional calendar and many traditional customs were based on the Chinese calendar. The ban failed and was lifted in 1934.[24] The latest Chinese calendar was "New Edition of Wànniánlì, revised edition", edited by Beijing Purple Mountain Observatory, People's Republic of China.[25]

Shíxiàn calendar

From 1645 to 1913 the Shíxiàn or Chongzhen was developed. During the late Ming dynasty, the Chinese Emperor appointed Xu Guangqi in 1629 to be the leader of the ShiXian calendar reform. Assisted by Jesuits, he translated Western astronomical works and introduced new concepts, such as those of Nicolaus Copernicus, Johannes Kepler, Galileo Galilei, and Tycho Brahe; however, the new calendar was not released before the end of the dynasty. In the early Qing dynasty, Johann Adam Schall von Bell submitted the calendar which was edited by the lead of Xu Guangqi to the Shunzhi Emperor.[26] The Qing government issued it as the Shíxiàn (seasonal) calendar. In this calendar, the solar terms are 15° each along the ecliptic and it can be used as a solar calendar. However, the length of the climate term near the perihelion is less than 30 days and there may be two mid-climate terms. The Shíxiàn calendar changed the mid-climate-term rule to "decide the month in sequence, except the intercalary month."[27] The present traditional calendar follows the Shíxiàn calendar, except:

  1. The baseline is Chinese Standard Time, rather than Beijing local time.
  2. (Modern) astronomical data, rather than mathematical calculations, is used.

Proposals

To optimize the Chinese calendar, astronomers have proposed a number of changes. Gao Pingzi (高平子; 1888–1970), a Chinese astronomer who co-founded the Purple Mountain Observatory, proposed that month numbers be calculated before the new moon and solar terms to be rounded to the day. Since the intercalary month is determined by the first month without a mid-climate and the mid-climate time varies by time zone, countries that adopted the calendar but calculate with their own time could vary from the time in China.[28]

Horology

Horology, or chronometry, refers to the measurement of time. In the context of the Chinese calendar, horology involves the definition and mathematical measurement of terms or elements such observable astronomic movements or events such as are associated with days, months, years, hours, and so on. These measurements are based upon objective, observable phenomena. Calendar accuracy is based upon accuracy and precision of measurements.

The Chinese calendar is lunisolar, similar to the Hindu, Hebrew and ancient Babylonian calendars. In this case the calendar is in part based in objective, observable phenomena and in part by mathematical analysis to correlate the observed phenomena. Lunisolar calendars especially attempt to correlate the solar and lunar cycles, but other considerations can be agricultural and seasonal or phenological, or religious, or even political.

Basic horologic definitions include that days begin and end at midnight, and months begin on the day of the new moon. Years start on the second (or third) new moon after the winter solstice. Solar terms govern the beginning, middle, and end of each month. A sexagenary cycle, comprising the heavenly stems (Chinese: 干; pinyin: gān) and the earthly branches (Chinese: 支; pinyin: zhī), is used as identification alongside each year and month, including intercalary months or leap months. Months are also annotated as either long (Chinese: 大; lit. 'big' for months with 30 days) or short (Chinese: 小; lit. 'small' for months with 29 days). There are also other elements of the traditional Chinese calendar.

Day

Days are Sun oriented, based upon divisions of the solar year. A day (日; rì) is considered both traditionally and currently to be the time from one midnight to the next. Traditionally days (including the night-time portion) were divided into 12 double-hours, and in modern times the 24 hour system has become more standard.

Month

Months are Moon oriented. Month (月; yuè), the time from one new moon to the next. These synodic months are about 29+17⁄32 days long. This includes the Date (日期; rìqī), when a day occurs in the month. Days are numbered in sequence from 1 to 29 (or 30). And, a Calendar month (日曆月; rìlì yuè), is when a month occurs within a year. Some months may be repeated.

Year

A year (年; nián) is based upon the time of one revolution of Earth around the Sun, rounded to whole days. Traditionally, the year is measured from the first day of spring (lunisolar year) or the winter solstice (solar year). A year is astronomically about 365+31⁄128 days. This includes the calendar (日曆; rìlì) year, when it is authoritatively determined on which day one year ends and another begins. The year usually begins on the new moon closest to Lichun, the first day of spring.[7] This is typically the second and sometimes third new moon after the winter solstice. A calendar year is 353–355 or 383–385 days long. Also includes Zodiac, 1⁄12 year, or 30° on the ecliptic. A zodiacal year is about 30+7⁄16 days.

Solar terms

Solar term (節氣; jiéqì), 1⁄24 year, or 15° on the ecliptic. A solar term is about 15+7⁄32 days.

Planets

The movements of the Sun, Moon, Mercury, Venus, Mars, Jupiter and Saturn (sometimes known as the seven luminaries) are the references for calendar calculations.

Stars

Big Dipper

The Big Dipper is the celestial compass, and its handle's direction indicates or some said determines the season and month.

3 Enclosures and 28 Mansions

The stars are divided into Three Enclosures and 28 Mansions according to their location in the sky relative to Ursa Minor, at the center. Each mansion is named with a character describing the shape of its principal asterism. The Three Enclosures are Purple Forbidden, (紫微), Supreme Palace (太微), and Heavenly Market. (天市) The eastern mansions are 角, 亢, 氐, 房, 心, 尾, 箕. Southern mansions are 井, 鬼, 柳, 星, 張, 翼, 轸. Western mansions are 奎, 婁, 胃, 昴, 畢, 參, 觜. Northern mansions are 斗, 牛, 女, 虛, 危, 室, 壁. The moon moves through about one lunar mansion per day, so the 28 mansions were also used to count days. In the Tang dynasty, Yuan Tiangang (袁天罡) matched the 28 mansions, seven luminaries and yearly animal signs to yield combinations such as "horn-wood-flood dragon" (角木蛟).

List of lunar mansions

The names and determinative stars of the mansions are:[29][30]

Four Symbols
(四象)		 Mansion (宿)
Number Name

(Pinyin)

Translation Determinative star
Azure Dragon
of the East
(東方青龍 - Dōngfāng Qīnglóng)
Spring
 1 角 (Jiǎo) Horn α Vir
2 亢 (Kàng) Neck κ Vir
3 氐 (Dī) Root α Lib
4 房 (Fáng) Room π Sco
5 心 (Xīn) Heart α Sco
6 尾 (Wěi) Tail μ¹ Sco
7 箕 (Jī) Winnowing Basket γ Sgr
Black Tortoise
of the North
(北方玄武 - Běifāng Xuánwǔ)
Winter

 8 斗 (Dǒu) (Southern) Dipper φ Sgr
9 牛 (Niú) Ox β Cap
10 女 (Nǚ) Girl ε Aqr
11 虛 (Xū) Emptiness β Aqr
12 危 (Wēi) Rooftop α Aqr
13 室 (Shì) Encampment α Peg
14 壁 (Bì) Wall γ Peg
White Tiger
of the West
(西方白虎 - Xīfāng Báihǔ)
Fall

 15 奎 (Kuí) Legs η And
16 婁 (Lóu) Bond β Ari
17 胃 (Wèi) Stomach 35 Ari
18 昴 (Mǎo) Hairy Head 17 Tau
19 畢 (Bì) Net ε Tau
20 觜 (Zī) Turtle Beak λ Ori
21 参 (Shēn) Three Stars ζ Ori
Vermilion Bird
of the South
(南方朱雀 - Nánfāng Zhūquè)
Summer

 22 井 (Jǐng) Well μ Gem
23 鬼 (Guǐ) Ghost θ Cnc
24 柳 (Liǔ) Willow δ Hya
25 星 (Xīng) Star α Hya
26 張 (Zhāng) Extended Net υ¹ Hya
27 翼 (Yì) Wings α Crt
28 軫 (Zhěn) Chariot γ Crv

Descriptive mathematics

Several coding systems are used to avoid ambiguity. The Heavenly Stems is a decimal system. The Earthly Branches, a duodecimal system, mark dual hours (時; 时; shí or 時辰; 时辰; shíchen) and climatic terms. The 12 characters progress from the first day with the same branch as the month (first Yín day (寅日) of Zhēngyuè; first Mǎo day (卯日) of Èryuè), and count the days of the month.

The stem-branches is a sexagesimal system. The Heavenly Stems and Earthly Branches make up 60 stem-branches. The stem branches mark days and years. The five Wu Xing elements are assigned to each stem, branch, or stem branch.

Heavenly
Stem		 Meaning
Original meaning Modern
甲 turtle shell first (book I, person A etc.), methyl group, helmet, armor, words related to beetles, crustaceans, fingernails, toenails
乙 fishguts second (book II, person B etc.), ethyl group, twist
丙 fishtail[31] third, bright, fire, fishtail (rare)
丁 nail fourth, male adult, robust, T-shaped, to strike, a surname
戊 halberd (not used)
己 threads on a loom[32] self
庚 evening star age (of person)
辛 to offend superiors[33] bitter, piquant, toilsome
壬 burden[34] to shoulder, to trust with office
癸 grass for libation[35] (not used)

Sexagenary system

Twelve branches

  Earthly
Branch 		Chinese Direction Season Lunar Month Double Hour
Mandarin
Zhuyin 		Mandarin
Pinyin
1 子 ㄗˇ zǐ 鼠
Rat		 0° (north) winter Month 11 11 pm to 1 am (midnight)
2 丑 ㄔㄡˇ chǒu 牛
Cow		 30° Month 12 1am to 3 am
3 寅 ㄧㄣˊ yín 虎
Tiger		 60° spring Month 1 3 am to 5 am
4 卯 ㄇㄠˇ mǎo 兎
Rabbit		 90° (east) Month 2 5 am to 7 am
5 辰 ㄔㄣˊ chén 竜 (龍)
Dragon		 120° Month 3 7 am to 9 am
6 巳 ㄙˋ sì 蛇
Snake		 150° summer Month 4 9 am to 11 am
7 午 ㄨˇ wǔ 馬
Horse		 180° (south) Month 5 11 am to 1 pm (noon)
8 未 ㄨㄟˋ wèi 羊
Sheep		 210° Month 6 1 pm to 3 pm
9 申 ㄕㄣ shēn 猿
Monkey		 240° autumn Month 7 3 pm to 5 pm
10 酉 ㄧㄡˇ yǒu 鶏 (鳥)
Chicken		 270° (west) Month 8 5 pm to 7 pm
11 戌 ㄒㄩ xū 犬
Dog		 300° Month 9 7 pm to 9 pm
12 亥 ㄏㄞˋ hài 猪
Wild boar		 330° winter Month 10 9 pm to 11 pm

Day

See caption
Explanatory chart for traditional Chinese time

China has used the Western hour-minute-second system to divide the day since the Qing dynasty.[36] Several era-dependent systems had been in use; systems using multiples of twelve and ten were popular, since they could be easily counted and aligned with the Heavenly Stems and Earthly Branches.

Week

As early as the Bronze Age Xia dynasty, days were grouped into nine- or ten-day weeks known as xún (旬).[37] Months consisted of three xún. The first 10 days were the early xún (上旬), the middle 10 the mid xún (中旬), and the last nine (or 10) days were the late xún (下旬). Japan adopted this pattern, with 10-day-weeks known as jun (旬). In Korea, they were known as sun (순,旬).

The structure of xún led to public holidays every five or ten days. Officials of the Han dynasty were legally required to rest every five days (twice a xún, or 5–6 times a month). The name of these breaks became huan (澣; 浣, "wash").

Grouping days into sets of ten is still used today in referring to specific natural events. "Three Fu" (三伏), a 29–30-day period which is the hottest of the year, reflects its three-xún length.[11] After the winter solstice, nine sets of nine days were counted to calculate the end of winter.[38]

The seven-day week was adopted from the Hellenistic system by the 4th century CE[citation needed], although its method of transmission into China is unclear. It was again transmitted to China in the 8th century by Manichaeans via Kangju (a Central Asian kingdom near Samarkand),[39][a][b] and is the most-used system in modern China.

Month

Months are defined by the time between new moons, which averages approximately 29+17⁄32 days. There is no specified length of any particular Chinese month, so the first month could have 29 days (short month, 小月) in some years and 30 days (long month, 大月) in other years.

A 12-month-year using this system has 354 days, which would drift significantly from the tropical year. To fix this, traditional Chinese years have a 13-month year approximately once every three years. The 13-month version has the same long and short months alternating, but adds a 30-day leap month (閏月; rùnyuè). Years with 12 months are called common years, and 13-month years are known as long years.

Although most of the above rules were used until the Tang dynasty, different eras used different systems to keep lunar and solar years aligned. The synodic month of the Taichu calendar was 29+43⁄81 days long. The 7th-century, Tang-dynasty Wùyín Yuán Calendar was the first to determine month length by synodic month instead of the cycling method. Since then, month lengths have primarily been determined by observation and prediction.

The days of the month are always written with two characters and numbered beginning with 1. Days one to 10 are written with the day's numeral, preceded by the character Chū (初); Chūyī (初一) is the first day of the month, and Chūshí (初十) the 10th. Days 11 to 20 are written as regular Chinese numerals; Shíwǔ (十五) is the 15th day of the month, and Èrshí (二十) the 20th. Days 21 to 29 are written with the character Niàn (廿) before the characters one through nine; Niànsān (廿三), for example, is the 23rd day of the month. Day 30 (when applicable) is written as the numeral Sānshí (三十).

History books use days of the month numbered with the 60 stem-branches: "卷009"  [Volume 9]. 宋史  [History of Song Dynasty] (in Chinese) – via Wikisource.