Chinese calendar

The Chinese calendar is a lunisolar calendar, incorporating elements of a lunar calendar with those of a solar calendar. It is not exclusive to China, but followed by many other Asian cultures as well.^[1] In most of East Asia today, the Gregorian calendar is used for day-to-day activities, but the Chinese calendar is still used for marking traditional East Asian holidays such as the Chinese New Year (the Spring Festival (春節)), the Duan Wu festival, and the Mid-Autumn Festival, and in astrology, such as choosing the most auspicious date for a wedding or the opening of a building. Because each month follows one cycle of the moon, it is also used to determine the phases of the moon.

In China, the traditional calendar is known as the "agricultural calendar" (traditional Chinese: 農曆; simplified Chinese: 农历; pinyin: nónglì) while the Gregorian calendar is known as the "common calendar" (traditional Chinese: 公曆; simplified Chinese: 公历; pinyin: gōnglì). Another name for the Chinese calendar is the "Yin Calendar" (traditional Chinese: 陰曆; simplified Chinese: 阴历; pinyin: yīnlì) in reference to the lunar aspect of the calendar, whereas the Gregorian calendar is the "Yang Calendar" (traditional Chinese: 陽曆; simplified Chinese: 阳历; pinyin: yánglì) in reference to its solar properties. The Chinese calendar was also called the "old calendar" (traditional Chinese: 舊曆; simplified Chinese: 旧历; pinyin: jiùlì) after the "new calendar" (traditional Chinese: 新曆; simplified Chinese: 新历; pinyin: xīnlì), i.e., the Gregorian calendar, was adopted as the official calendar. For more than two thousand years, since the time of Emperor Wu of Han the month containing the winter solstice has almost always been the 11th month. (This means the new year starts on the second new moon after the winter solstice unless there is an 11th or 12th intercalary month, in which case it starts on the third new moon.) A calendar using this new year is often referred to as "the Xia Calendar" (traditional Chinese: 夏曆; simplified Chinese: 夏历; pinyin: xiàlì), following a comment in the Shiji which states that under the Xia Dynasty, the year began on the second new moon after the winter solstice. At times under some other dynasties in ancient China, the month with the winter solstice was the 12th or the 1st month.

The year 2011 in the Chinese calendar is the Year of the Rabbit. It began on February 3, 2011 and will end on January 22, 2012. According to traditional beliefs, some form of the calendar has been in use for almost five millennia. Based on archaeological evidence some form of it has been in use for three and a half millennia. The Chinese year beginning February 3, 2011 is reckoned in the seldom-used continuously numbered system to be 4709 (or 4649 or 4710, depending on the epoch used, see Continuously numbered years).

History

Early history

The earliest evidence of the Chinese calendar is found on the oracle bones of the Shang Dynasty (late second millennium BC), which seem to describe a lunisolar year of 12 months, with a possible intercalary 13th, or even 14th, added empirically to prevent calendar drift. The Sexagenary cycle for recording days was already in use. Tradition holds that, in that era, the year began on the first new moon after the winter solstice.

Early Eastern Zhou texts, such as the Spring and Autumn Annals, provide better understanding of the calendars used in the Zhou dynasty. One year usually had 12 months, which were alternately 29 and 30 days long (with an additional day added from time to time, to catch up with "drifts" between the calendar and the actual moon cycle), and intercalary months were added in an arbitrary fashion at the end of the year.

These arbitrary rules on day and month intercalation caused the calendars of each state to be slightly different, at times. Thus, texts like the Annals will often state whether the calendar they use (the calendar of Lu) is in phase with the Royal calendar (used by the Zhou kings).

Although tradition holds that in the Zhou, the year began on the new moon which preceded the winter solstice, the Spring and Autumn Annals seem to indicate that (in Lu at least) the Yin calendar (the calendar used in Shang dynasty, with years beginning on the first new moon after the winter solstice) was in use until the middle of the 7th century, and that the beginning of the year was shifted back one month around 650 BC.

By the beginning of the Warring States, progress in astronomy and mathematics allowed the creation of calculated calendars (where intercalary months and days are set by a rule, and not arbitrarily). The sìfēn 四分 (quarter remainder) calendar, which began about 484 BC, was the first calculated Chinese calendar, so named because it used a solar year of 365¼ days (the same as the 1st century BC Julian Calendar of Rome), along with a 19-year (235-month) Rule Cycle, known in the West as the Metonic cycle.^[2] The year began on the new moon preceding the winter solstice, and intercalary months were inserted at the end of the year.

In 256 BC, as the last Zhou king ceded his territory to Qin, a new calendar (the Qin calendar) began to be used. It followed the same principles as the Sifen calendar, except the year began one month before (the second new moon before the winter solstice, which now fell in the second month of the year). The Qin calendar was used during the Qin dynasty, and in the beginning of the Western Han dynasty.

Taichu calendar

The Emperor Wu of the Western Han dynasty introduced reforms that have governed the Chinese calendar ever since. His Tàichū (太初, "Grand Inception") calendar of 104 BC had a year with the winter solstice in the 11th month and designated as intercalary any calendar month (a month of 29 or 30 whole days) during which the sun does not pass a principal term (that is, remained within the same sign of the zodiac throughout). The solar year of the Taichu calendar was defined as 365 days and the lunar month as 29 days. Because the sun's mean motion was used to calculate the jiéqì (traditional Chinese: 節氣; simplified Chinese: 节气) (or seasonal markings) until 1645, this intercalary month was equally likely to occur after any month of the year. The conjunction of the sun and moon (the astronomical new moon) was calculated using the mean motions of both the sun and moon.

True sun and moon

Though the fact of the irregularity of the lunar orbit was known in the 1st century BC, the starts of the months were calculated using the mean motions of both the sun and moon until 619, the second year of the Tang dynasty, when chronologists began to use true motions modeled using two offset opposing parabolas (with small linear and cubic components). Unfortunately, the parabolas did not meet smoothly at the mean motion, but met with a discontinuity or jump.

With the introduction of European astronomy into China via the Jesuits, the motions of both the sun and moon began to be calculated with sinusoids in the 1645 Shíxiàn calendar (時憲書, Book of the Conformity of Time) of the Qing dynasty, made by the Jesuits Adam Schall and Giacomo Rho. The true motion of the sun was now used to calculate the jiéqì, which caused the intercalary month to often occur after the second through the ninth months, but rarely after the tenth through first months. A few autumn-winter periods have two or three calendar months where the sun stays within one sign, interspersed with one or two calendar months where the sun enters two signs of the zodiac.

Gregorian reform

The Gregorian calendar was adopted by the nascent Republic of China effective January 1, 1912 for official business, but the general populace continued to use the traditional calendar. The status of the Gregorian calendar was unclear between 1916 and 1921 while China was controlled by several competing warlords each supported by foreign colonial powers. From about 1921 until 1928 warlords continued to fight over northern China, but the Kuomintang or Nationalist government controlled southern China and used the Gregorian calendar. After the Kuomintang reconstituted the Republic of China October 10, 1928, the Gregorian calendar was officially adopted, effective January 1, 1929. The Peoples Republic of China has continued to use the Gregorian calendar since 1949.

Standard time

Before 1929, the traditional calendar was calculated by the Central Observatory (formerly the Imperial Observatory) in Beijing using Beijing local time at a longitude of 116°25'E (GMT+7h 45m 40s). From 1929 to 1949 it was calculated by the Institute of Astronomy in Nanjing and since 1949 by the Purple Mountain Observatory outside of Nanjing using Chinese standard time at a longitude of 120°E (GMT+8h). This shifted the midnight marking the beginning of each day in both the traditional and Gregorian calendars by plus 14 minutes 20 seconds. This shift meant that any dark moon which formerly occurred just before midnight Beijing local time now occurred just after midnight Chinese standard time, causing the first day of a lunar month to occur one day later. However, unlike the official tables, most public calendars relied on the old Wannian Shu (Long-term (lit. "10,000-year) Calendar；simplified Chinese: 万年书; traditional Chinese: 萬年書) last published in 1910 using Beijing time until they were forced to adopt the official traditional calendar using Chinese standard time when the two disagreed. In 1953 public calendars placed the dark moon and the first day of a lunar month on August 9, whereas the official traditional calendar placed it on August 10, which caused public calendars in most of the People's Republic of China to use the official tables and standard time after 1953. In 1978 the dates were respectively September 2 and 3, causing public calendars in the Hong Kong and Canton areas to do the same after 1978. In 1989 the dates were August 1 and 2, which caused Taiwan to do the same after 1989.^[3][4]

Calendar rules

The following rules outline the Chinese calendar since 104 BC. Note: the rules allow either mean or true motions of the Sun and Moon to be used, depending on the historical period.

1. The months are lunar months. This means the first day of each month beginning at midnight is the day of the astronomical dark moon. (This differs from a traditional Chinese "day" which begins at 11 p.m.).
2. Each year has 12 regular months, which are numbered in sequence (1 to 12) and have alternative names. Every second or third year has an intercalary month (traditional Chinese: 閏月; simplified Chinese: 闰月; pinyin: rùnyuè), which may come after any regular month. It has the same number as the preceding regular month, but is designated intercalary.
3. Every other jiéqì of the Chinese solar year is equivalent to an entry of the sun into a sign of the tropical zodiac (a principal term or cusp).
4. The sun always passes the winter solstice (enters Capricorn) during month 11.
5. If there are 12 months between two successive occurrences of month 11, not counting either month 11, at least one of these 12 months must be a month during which the sun remains within the same zodiac sign throughout (no principal term or cusp occurs within it). If only one such month occurs, it is designated intercalary, but if two such months occur, only the first is designated intercalary. Note that for calendars before true motions of the sun were used for naming (i.e., before 1645), or in years where there is no double-cusp month in that year or the previous or following years (i.e., usually), the following rule suffices: a month with no principal term (or cusp) in it is designated intercalary.
6. The times of the astronomical new moons and the sun entering a zodiac sign are determined using the time in the Chinese Time Zone by the Purple Mountain Observatory (Chinese: 紫金山天文台; pinyin: Zǐjīnshān Tiānwéntái) outside Nanjing using modern astronomical equations.

Correspondence with Western Zodiac

The zodiac sign which the sun enters during the month and the ecliptic longitude of that entry point usually determine the number of a regular month. Month 1 (正月 zhēngyuè), literally means principal month. All other months are literally numbered, second month, third month, and so on.

Exceptions

There are exceptions, which, for example, prevent Chinese New Year from always being the second new moon after the winter solstice, or that cause the holiday to occur after the Rain Water jieqi. An exception will occur in 2033–2034, when the winter solstice is the second solar term in the 11th month. The next month is a no-entry month and so is intercalary, and a twelfth month follows which contains both the Aquarius and Pisces solar terms (deep cold and rain water). The Year of the Tiger thus begins on the third new moon following the Winter Solstice, and also occurs after the Pisces (rain water) jieqi, on February 19.

Another occurrence was in 1984–85, after the sun had entered both Capricorn at 270° and Aquarius at 300° in month 11, and then entered Pisces at 330° during the next month, which should have caused it to be month 1. The sun did not enter any sign during the next month. In order to keep the winter solstice in month 11, the month which should have been month 1 became month 12, and the month thereafter became month 1, causing Chinese New Year to occur on February 20, 1985 after the sun had already passed into Pisces at 330° during the previous month, rather than during the month beginning on that day.

A lunar month is always either 29 or 30 days long, because the length of the synodic month (the cycle of the phases of the Moon) is approximately 29.53 days. The length of time the Sun is in one of the signs of the tropical Zodiac varies from about 30 days at perihelion to about 32 days at aphelion, because each sign represents an equal 30° geometrical expanse of the Earth's orbit around the Sun, and this orbit is an ellipse instead of a perfect circle, and is governed by Kepler's Second Law.

On those occasions when a dual-entry month does occur, it always occurs somewhere between two months that do not have any entry (non-entry months), because the maximum length of a lunar month is only very slightly greater than the minimum length of time the Sun spends in an astrological sign. It usually occurs alone and either includes or is near the winter solstice, because the Earth is at aphelion on or around July 4, and at perihelion, when the Sun moves the most quickly through astrological signs, on or around January 3, which is not far from the winter solstice, which takes place on or around December 22.

The fact that the winter solstice is required to fall in month 11 (rule 4) fixes the start and end points of the span between the occurrences of month 11 in two successive years. Therefore, it is possible to apply the rule that the first of the 12 months between two occurrences of month 11 in which the Sun enters no new astrological sign is to be taken as the intercalary month (rule 5) in an unambiguous fashion. In 1984–85, the month immediately before the dual-entry month 11 was a non-entry month that was designated as an intercalary month 10. All months from the dual-entry month to the non-entry month that is not to be intercalary are sequentially numbered with the nearby regular months (rule 2). The last phrase of rule 5, choosing the first of two non-entry months between months 11, has not been required since the last calendar reform, and will not be necessary until the Chinese year spanning the Western years 2033–34, when two dual-entry months will be interspersed among three non-entry months, two of which will be on one side of month 11. The leap 11th month produced is a very rare event.^[5]

Exceptions such as these are rare. Fully 96.6% of all months contain only one entry into a zodiacal sign (have one principal term or cusp), all obeying the numbering rules of the jiéqì table, and 3.0% of all months are intercalary months (always non-entry months between principal terms or cusps). Only 0.4% of all months are either dual-entry months (have two principal terms or cusps) or neighboring months that are renumbered.

It is only after the 1645 reform that this situation arose. Then it became necessary to fix one month to always contain its principal term and allow any other to occasionally not contain its principal term. Month 11 was chosen, because its principal term (the winter solstice) forms the start of the Chinese Solar year (the sui).

Nineteen year cycle

The Chinese lunar calendar and the Gregorian Calendar often sync up every 19 years (Metonic cycle). Most Chinese people notice that their Chinese and Western birthdays often fall on the same day on their 19th, 38th birthday and so on. However, a 19-year cycle with a certain set of intercalary months is only an approximation, so an almost identical pattern of intercalary months in subsequent cycles will eventually change after some multiple of 19 years to a quite different 19-year cycle.

Lunar months

The Chinese zodiac (see also Twelve Animals section) is only used in naming years—it is not used in the actual calculation of the calendar. In fact, the Chinese have a very different constellation system.

In modern China, the lunar months are typically simply numbered, following the standard practice with the solar months. However, the old names for the first (正月, p Zhēngyuè or 元月, p Yuányuè, both meaning "first month") and last (t 臘月, s 腊月, p Làyuè) months are still used as well.

Among the many variant series for naming months is the following, which mostly uses flower names.

Year markings

Regnal years

Traditional Chinese years were not continuously numbered in the way that the BC/AD system is. More commonly, official year counting always used some form of a regnal year. This system began in 841 BC during the Zhou dynasty. Prior to this, years were not marked at all, and historical events cannot be dated exactly.

In 841 BC, the King Li of Zhou (周厲王) was ousted by a civilian uprising (國人暴動), and the country was governed for the next 14 years by a council of senior ministers, a period known as the Regency (共和行政). In this period, years were marked as First (second, third, etc.) Year of the Regency.

Subsequently, years were marked as regnal years, e.g., the year 825 BC was marked as the 3rd Year of the Xuan King Jing of Zhou (周宣王三年). This system was used until early in the Han dynasty, when the Wen Emperor of Han (漢文帝劉恒) instituted regnal names. After this, most emperors used one or more regnal names to mark their reign. Usually, the emperor would institute a new name upon accession to the throne, and then change to new names to mark significant events, or to end a perceived cycle of bad luck. In the Ming and Qing dynasties, however, each emperor usually used only one regnal name for his reign.

This system continued until the Republic of China, which counted years as Years of the Republic, beginning in 1912. Thus, 1912 is the 1st Year of the Republic, 1949 the 38th, and 2011 the 100th. This system is still commonly used in Taiwan. In 1949 the People's Republic of China chose to use the Common Era system (equivalently, AD/BC system), in line with international standards.

Stem-branch cycle

The other system by which years are marked historically in China was by the stem-branch or sexagenary cycle. This system is based on two forms of counting: a cycle of 10 Heavenly Stems and a cycle of 12 Earthly Branches. Each year is named by a pair of one stem and one branch called a Stem-Branch (干支 gānzhī). The Heavenly Stems are associated with Yin Yang and the Five Elements. Recent 10-year periods began in 1984, 1994, and 2004. The Earthly Branches are associated with the 12 signs of the zodiac. Each Earthly Branch is also associated with an animal, collectively known as the Twelve Animals. Recent 12-year periods began in 1984, 1996 and 2008.

Within the Heavenly Stems system the year is advanced up by one per year, cycling back to year one after the last (year ten). Similarly the Earthly Branches also advances by one per year, cyclically. Since the numbers 10 (Heavenly Stems) and 12 (Earthly Branches) have a common factor of 2, only 1/2 of the 120 possible stem-branch combinations actually occur. The resulting 60-year (or sexagesimal) cycle takes the name jiǎzǐ (甲子) after the first year in the cycle, being the Heavenly Stem of jiǎ and Earthly Branch of zǐ. The term "jiǎzǐ" is used figuratively to mean "a full lifespan"—one who has lived more than a jiǎzǐ is obviously blessed. (Compare the Biblical "three-score years and ten.")

At first, this system was used to mark days, not years. The earliest evidence of this was found on oracle bones dated c.1350 BC in the Shang Dynasty. This system of date marking continues to this day, and can still be found on Chinese calendars today. Although a stem-branch cannot be used to deduce the actual day in historical events, it can assist in converting Chinese dates to other calendars more accurately.

Around the Han Dynasty, the stem-branch cycle also began to be used to mark years. The 60-year system cycles continuously, and determines the animal or sign under which a person is born (see Chinese Zodiac). These cycles were not named, and were used in conjunction with regnal names declared by the emperor. For example: 康熙壬寅 (Kāngxī rényín) (1662 AD) is the first 壬寅 (rényín) year during the reign of 康熙 (Kāngxī), regnal name of an emperor of the Qing Dynasty

The months, days and hours can also be denoted using Heavenly Stems and Earthly Branches, though they are commonly addressed using Chinese numerals instead. In Chinese astrology, four Stem-Branch pairs form the Eight Characters (八字 bāzì).

Continuously numbered years

There is no universally agreed upon "epoch" or starting point for the Chinese calendar. Tradition holds that the calendar was invented by Emperor Huang-di (黄帝) in the 61st year of his reign in what is now known under the proleptic Gregorian calendar as 2637 BC. Many have used this date as the epoch, i.e. the first year of the first sixty-year (sexagesimal) cycle, of the Chinese calendar, but others have used the date of the beginning of his reign in 2697 BC as the epoch. Since these dates are exactly sixty years apart, it does not matter which is used to determine the stem/branch sequence or the astrological sign for any succeeding year. That is, 2006 is a bingxu year and the Year of the Dog regardless of whether years are counted from 2637 BC or 2697 BC.

For the most part, the imposition of a continuous numbering system on the Chinese calendar was of interest mostly to Jesuit missionaries and other Europeans who assumed that calendars obviously had to be continuous. However, in the early 20th century, some Chinese Republicans began to advocate widespread use of continuously numbered years, so that year markings would be independent of the Emperor's regnal name. (This was part of their attempt to delegitimise the Qing Dynasty.) When Sun Yat-sen became the provisional president of the Republic of China, he sent telegrams to leaders of all provinces and announced the 13th day of 11th Month of the 4609th year of the Yellow Emperor's reign (corresponding to 1 January 1912) to be the 1st year of the Republic of China. His choice was adopted by many overseas Chinese communities outside Southeast Asia such as San Francisco's Chinatown.

Correspondence between systems

This table shows the stem/branch year names, correspondences to the Western (Gregorian) calendar, and other related information for the current decade.^[7] (These years are all part of the 79th sexagenary cycle, or the 78th if an epoch of 2637 BC is accepted.) Or see this larger table of the full 60-year cycle.

Notes

¹ The beginning of each zodiac year should correspond to the first day of the lunar year.

² As discussed above, there is considerable difficulty in establishing a basis for the chronology of the continuous year numbers. The numbers listed here are too high by 60 if an epoch of 2637 BC is accepted. They may be too low by 1 if an epoch of 2698 BC is accepted. That is, according to some sources, Gregorian 2006 (Chinese 4703) could alternatively correspond to 4643, or perhaps 4704. Chinese Americans in the United States use the epoch of 2698 BC as the basis for numbering the years, and therefore Gregorian 2006 is numbered as 4704 and so forth for previous and subsequent years.

³ In any case, the correspondence between a lunisolar Chinese year and a solar Gregorian year is of course not exact. The first few months of each Gregorian year—those preceding Chinese New Year—belong to the previous Chinese year. For example, January 1 – January 28, 2006 correspond to yǐyǒu or 4702. Thus, it might be more precise to state that Gregorian 2006 corresponds to 4702–4703, or that continuous Chinese 4703 corresponds to 2006–2007.

Solar year versus lunar year

There is a distinction between a solar year and a lunar year in the Chinese calendar because the calendar is lunisolar. A lunar year (年 nián) is from one Chinese new year to the next. A solar year (歲 suì) is either the period between one Spring Equinox and the next or the period between two winter solstices (see Jiéqì section). A lunar year is exclusively used for dates, whereas a solar year, especially that between winter solstices, is used to number the months.

Hours of the day

Under the traditional system of hour-marking, each day is divided into 12 units (時辰). Each of these units is equivalent to two hours of international time. Each is named after one of the 12 Earthly Branches. The first unit, Hour of Zi (子時), begins at 11 p.m. of the previous day and ends at 1 a.m. Traditionally, executions of condemned prisoners occur at the midpoint of Hour of Wu (正午時), i.e., noon.

A second system subdivided the day into 100 equal parts, ke, each of which equalling 14.4 minutes or about one quarter of a standard Western hour. This was used for centuries, making the Chinese first to apply decimal time – long before the French Republican Calendar. However, because 100 could not be divided equally into the 12 "double hours", the system was changed to variously 96, 108, and 120 ke in a day. During the Qing Dynasty, the number was officially settled at 96, making each ke exactly a quarter of a Western hour. Today, ke is often used to refer to a quarter of an hour.

12 animals

The 12 animals (十二生肖 shí'èr shēngxiào, "twelve birth emblems" or colloquially 十二屬相 shí'èr shǔxiàng, "twelve signs of belonging") representing the 12 Earthly Branches are, in order, the Rat, Ox, Tiger, Rabbit, Dragon, Snake, Horse, Goat, Monkey, Rooster, Dog, and Pig.

A legend explains the sequence in which the animals were assigned. Supposedly, the 12 animals fought over the precedence of the animals in the cycle of years in the calendar, so the Chinese gods held a contest to determine the order. All the animals lined up on the bank of a river and were given the task of getting to the opposite shore. Their order in the calendar would be set by the order in which the animals managed to reach the other side. The cat wondered how he would get across if he was afraid of water. At the same time, the ox wondered how he would cross with his poor eyesight. The calculating rat suggested that he and the cat jump onto the ox's back and guide him across. The ox was steady and hard-working so that he did not notice a commotion on his back. In the meanwhile, the rat sneaked up behind the unsuspecting cat and shoved him into the water. Just as the ox came ashore, the rat jumped off and finished the race first. The lazy pig came to the far shore in twelfth place. And so the rat got the first year named after him, the ox got the second year, and the pig ended up as the last year in the cycle. The cat finished too late to win any place in the calendar, and vowed to be the enemy of the rat forevermore.

Solar term

Chinese months follow the phases of the moon. As a result, they do not accurately follow the seasons of the solar year. To assist farmers to decide when to plant or harvest crops, the drafters of the calendar put in 24 seasonal markers, which follow the solar year, and are called jiéqì (節氣).

The term Jiéqì is usually translated as "Solar Terms" (lit. Nodes of Weather). Each node is the instant when the sun reaches one of 24 equally spaced points along the ecliptic, including the solstices and equinoxes, positioned at 15 degree intervals. Because the calculation is solar-based, these jiéqì fall around the same date every year in solar calendars (for example, the Gregorian Calendar), but do not form any obvious pattern in the Chinese calendar. The dates below are approximate and may vary slightly from year to year due to the intercalary rules (i.e. system of leap years) of the Gregorian calendar. Jiéqì are published each year in farmers' almanacs. Chinese New Year is usually the new moon closest to lìchūn.

In the table below, these measures are given in the standard astronomical convention of ecliptic longitude, zero degrees being positioned at the vernal equinox point. Each calendar month under the heading "M" contains the designated jiéqì called a principal term, which is an entry into a sign of the zodiac, also known as a cusp. Here term has the archaic meaning of a limit, not a duration. In Chinese astronomy, seasons are centered on the solstices and equinoxes, whereas in the standard Western definition, they begin at the solstices and equinoxes. Thus the term Beginning of Spring and the related Spring Festival fall in February, when it is still very chilly in temperate latitudes in the Northern Hemisphere.

Note: The third jiéqì was originally called 啓蟄 (qǐzhé) but renamed to 驚蟄 (jīngzhé) in the era of the Emperor Jing of Han (漢景帝) to avoid writing his given name 啓 (also written as 啟, a variant of 啓).

Holidays

The Chinese calendar year has nine main festivals, seven determined by the lunisolar calendar, and two derived from the solar agricultural calendar. (Farmers actually used a solar calendar, and its 24 terms, to determine when to plant crops, due to the inaccuracy of the lunisolar traditional calendar. However, the traditional calendar has also come to be known as the agricultural calendar.) The two special holidays are the Qingming Festival and the Winter Solstice Festival, falling upon the respective solar terms, at ecliptic longitudes of 15° and 270°, respectively. As for all other calendrical calculations, the calculations use civil time in China, UTC+08

Purpose of the intercalary months

Most people, upon using or studying the Chinese calendar, are perplexed by the intercalary month because of its seemingly unpredictable nature. As mentioned above, the intercalary month refers to additional months added to the calendar in some years to correct for its deviation from the astronomical year, a function similar to that of the extra day in February in leap years.

However, because of the complex astronomical knowledge required to calculate if and when an intercalary month needs to be inserted, to most people, it is simply a mystery. This has led to a superstition that intercalary months in certain times of the year bring bad luck.

The main purpose of the intercalary month is to correct for deviations of the calendrical year from the astronomical year. Because the Chinese calendar is mainly a lunar calendar, its standard year is 354 days, whereas the astronomical year is approximately 365¼ days. Without the intercalary month, this deviation would build up over time, and the Spring festival, for example, would no longer fall in Spring. Thus, the intercalary month serves a valuable purpose in ensuring that the year in the Chinese calendar remains approximately in line with the astronomical year.

The intercalary month is inserted whenever the Chinese calendar moves too far from the stage of progression of the earth in its orbit. Thus, for example, if the beginning of a certain month in the Chinese calendar deviates by a certain number of days from its equivalent in a solar calendar, an intercalary month needs to be inserted.

The practical benefit of this system is that the calendar is able to approximately keep in pace with the solar cycle, while at the same time retaining months that roughly correspond with lunar cycles. Hence the term lunisolar calendar. The latter is important because many traditional festivals correspond to significant events in the moon's cycle. For example, the mid-autumn festival is always on a day of the full moon.

Relevance of the calendar today

There have been calls for reform in recent years from experts in China, because of the increasing irrelevance of the Chinese calendar in modern life. They point to the example in Japan, where during the Meiji Restoration the nation adopted the Gregorian calendar, and simply shifted all traditional festivities onto an equivalent date. However, the Chinese calendar remains important as an element of cultural tradition, and for certain cultural activities.

Practical uses

The original practical relevance of the lunisolar calendar for date marking has largely disappeared. First, the Gregorian calendar is much easier to compute and more in line with international standards. Its adoption for official purposes has meant that the traditional calendar is rarely used for date marking. This, in turn, means that it is more convenient to remember significant events such as birth dates by the Gregorian rather than the Chinese calendar.

Second, the 24 solar terms were important to farmers who would not be able to plan agricultural activities without foreknowledge of these terms. However, the 24 solar terms (including the solstices and equinoxes) are more predictable on the Gregorian calendar than the lunisolar calendar since they are based on the solar cycle. It is easier for the average Chinese farmer to organize their planting and harvesting with the Gregorian calendar.

However, one practical advantage of using a calendar where the months are lunar months is that the phases of the moon, and astronomical and tidal phenomena associated with them, such as spring and neap tides, fall on approximately the same day in each lunar month, and the times of high and low water and the tidal streams experienced in a certain location on a certain day of the lunar month are likely to be similar to those for the same place and lunar day in any month. For many years, therefore, mariners in East and South-East Asia have related their tidal observations to the Chinese calendar, so as to be able to provide quick, rule-of-thumb approximations of tides and tidal conditions from memory, based on the day of the Lunar month, without needing to refer to tide tables. Certain inshore passages on the China coast, for example, where there are strong tidal streams associated with spring tides, were regarded by mariners to be passable on certain days of the lunar month, and impassable on others.

Cultural issues

The Chinese calendar remains culturally essential today. For example, most of the traditional festivals, such as Chinese New Year and the Mid-Autumn Festival, occur on new moons or full moons. The traditional Chinese calendar, as an element of traditional culture, has much cultural and nationalistic sentiment invested in it.

The calendar is still used in the more traditional Chinese households around the world to pick 'auspicious dates' for important events such as weddings, funerals, and business deals. A special calendar is used for this purpose, called Huang Li (traditional Chinese: 皇曆; simplified Chinese: 皇历; pinyin: huánglì), literally "Imperial Calendar", which contains auspicious activities, times, and directions for each day. The calendar follows the Gregorian dates but has the corresponding Chinese dates. Every date would have a comprehensive listing of astrological measurements and fortune elements.

Influence

Other traditional East Asian calendars are very similar to if not identical to the Chinese calendar: the Korean calendar is identical; the Vietnamese calendar substitutes the cat for the rabbit in the Chinese zodiac; the Tibetan calendar differs slightly in animal names, and the traditional Japanese calendar uses a different method of calculation, resulting in disagreements between the calendars in some years. The Thai lunar calendar also share a lot of similarities with the Chinese calendar.

The 12 year cycle, with the animal names translated into the vernacular, was adopted by the Göktürks (its use there is first attested 584), and spread subsequently among many if not most Turkic peoples, as well as the Mongols. A similar calendar seems to have been used by the Bulgars, as attested in the Nominalia of the Bulgarian Khans and in some other documents. The main differences between the Bulgar and the Chinese calendar are the different calculating system, the tiger has been replaced with a wolf, and the dragon and monkey—with an unknown animal. Also, the Bulgar calendar is a solar one.^[9]

Chinese-Uighur calendar

In 1258, when both North China and the Islamic world were part of the Mongol Empire, Hulagu Khan established an observatory in Maragheh for the astronomer Nasir al-Din al-Tusi at which a few Chinese astronomers were present, resulting in the Chinese-Uighur calendar that al-Tusi describes in his Zij-i Ilkhani.^[10] The 12 year cycle, including Turkish/Mongolian translations of the animal names (known as sanawat-e turki سنوات ترکی,) remained in use for chronology, historiography, and bureaucratic purposes in the Persian and Turkish speaking world from Asia Minor to India and Mongolia throughout the Medieval and Early Modern periods. In Iran it remained common in agricultural records and tax assessments until a 1925 law deprecated its use.

See also

• Culture of China
• East Asian age reckoning
• Sexagesimal cycle

References

External links

Calendars

• Chinese months
• Chinese day with auspicious times
• Gregorian-Lunar calendar years (1900–2100)

Calendar conversion

• Chinese Lunar calendar with Chinese Festivals (1901–2049)
• Western-Chinese calendar converter (since 1912)
• 2000-year Chinese-Western calendar converter From 1 AD to 2100 AD. Useful for historical studies. Put the western year 年 month 月day 日in the bottom row and click on 執行.

Rules

• Rules for the Chinese Calendar
• The Structure of the Chinese Calendar