History of Chinese Calender

HISTORY OF CHINESE CALENDAR
The Chinese civilization is the only one which has developed and used two parallel calendar systems,  and thereby, one might say, has enjoyed the best of both worlds, lunar  and solar. Both solar and lunar calendars take as  their basic counting unit, the year, corresponding with greater or less  exactitude to he period of the earth’s  revolution around the sun, and the month, approximating the period of the moon’s  revolution around the earth.

Astronomers  describe the motions of these heavenly bodies with mathematical accuracy and  thereby define units of time which one may call the natural year and  the natural month or lunation. The traditional Chinese calendar is  basically lunar. It consists of twelve months, each beginning with a  new moon and reaching its midpoint with the full moon. The twelve lunations  total three hundred fifty-four  days, which means that individual lunation have a length of either twenty-nine or thirty days.

The framers  needed a calendar that would tell them the best  times  for planting and harvests, activities that followed the seasons  of the natural year. In short, they needed a solar calendar. The ancient Chinese astronomers  provided a luni-solar calendar for their needs that was both simple and accurate. However, the development  of the calendar and the establishing of the seasons, holidays and the New Year was too scientific and complicated for most of the people to understand. Thus  a number  of stories and folk  tales developed which simplified its explanation.

The ‘perpetual calendar’ or the ‘Wan-nien-li’  is  said  to  be  created  by  a man named Wan-nien during the Shang dynasty(1766-1123 B.C.). He resorted to  methods of measuring time  by noting the length of the shadows throughout the year with  a gnomon and gnomon template and the length of each day with a clepsyda(water-clock).  By empirical observation and with these measurements  of the longest  and shortest  days  in the year, he was able to establish the two solstices and  in turn the two equinoxes. Moreover, he concluded that there were  three hundred sixty-five  and a fraction of  days within a year’s time. Traditionally,  Chinese astronomy  is  traced back to the time of the legendary emperor, Fu-hsi(2852.B.C.). The measurements and reverent calculations of the royal astronomers provided the basis for the imperial calendar and almanac. The almanac  fixed the lengths of the months, determined the dates of the spring  and autumn equinoxes – the times a year that night and day are  of  equal length – and of  the summer and winter solstices  – when night and  day differ most in length. 

Calendars are all based on the cyclical movements of one or more celestial bodies. In our international calendar, it is  the sun, in the Muslim calendar it  is the moon, and in the  Chinese calendar it was the sun,  the moon and during a certain period, the planet Jupiter. The most difficult problem for  the astronomers  plotting the almanac was the determination of the length of  the solar year –  that is, the exact length of time required to complete  the cycle of seasons. The ancient estimation had been that it was  three hundred sixty-six  days; this  figure was revised to  three hundred sixty-five and  a quarter days  by  the fourth century B.C., and this calculation was constantly  refined thereafter. The Chinese based many of their  computations not on  the sun but on the position of the pole star and the wheeling around it of circumpolar constellations like the Ursa Major(Big Dipper); its handle pointing north in winter, south in summer, marked the twelve months of the Chinese year. The movement of the planet Jupiter, which was called  T’ai-sui  (year star) and whose orbit takes twelve years to complete, was also taken into  account in the Chinese division of periodic time. Finally, the phases of the  moon, from dark  to  full, which bear no fixed relationship to the solar  year, had to be included in  the computations so that the calendar months could be adjusted to fit the year. The Chinese watched the waxing and  waning of the moon which gave them the idea of a month,  which they appropriately  called  Yueh  or a complete cycle of the moon from new moon to new moon. 

They  also observed that it took twelve months to  cover the four seasons, and thus  they formed the notion of a year. A year was first called  Sul  as  it was  one of the units of a  full cycle  of the Pole Star, but later the term  Nien  was used. However,  these simple  calculations  were  not, and could not be,  exact. Between a new moon and the  next, it is not twenty-nine or thirty days, but twenty-nine and a half days, making the cumulative total,  eleven and a quarter days  shorter than  the three hundred sixty-five  and a quarter days  of a full year. So for a lunar calendar to  be  accurate,  it is necessary to  insert once in  every two or  three  years,  a leap month like  the leap day of the solar calendar, to catch up with  the motions  of the earth.  However, in order to know when to insert the leap month so  that all the seasons are as properly proportioned as they should be, it is essential first to ascertain the winter and summer solstices as well as the  vernal and autumnal equinoxes. The ancients, however, did not  come to such knowledge easily; it  took centuries. To determine how to  position the  lunar months, the Chinese used a solar sequence consisting  of twenty-four nodes or  Chieh-ch’I  spaced at approximately fifteen day intervals  through the year.  The primary nodes were  those of the two solstices (Erh chih), two equinoxes (Erh-fen), and spaced evenly  between solstices  and equinoxes, the Chinese four beginnings  of the seasons  (Ssu-li). These are continued on from year to year, irrespective of  the lunar  intersalations, and are referred to by the Chinese as the  Chung-ch’I  (mid-periods)  and  Chieh-ch’I  (nodes). Because the popular  Ch’ing-ming  festival is  considered one of the  Chieh-ch’I  or nodes, it always falls on April fifth on  the Gregorian calendar  except in leap years when it is on April fourth. There are twelve in each category. Each Chieh  is followed by a  Chung  which is followed by a  Chieh. These periods are determined solely by the solar  cycle, each corresponding  to a movement  of about five degrees in  longitude by the  sun on the ecliptic or the days on which the sun enters the  first and fifteen degrees of each Zodiac  sign. The lunar months are then superimposed on the twenty-four  Chiehch’i. Since the synodic period of the moon is about 29.53 days, and for practical reasons, the Chinese worked  in whole numbers, the result was a twenty-nine or thirty day  lunar month. The Chinese  referred to  tjose months respectively as  Yueh-hsiao  and  Yueh-ta. Normally each lunar  month will have one  Chieh  and one  Chung  with the  Chung  occurring near the middle of  the month. Since the interval between two successive  Chieh  is approximately 30.43 days, occasionally there occur months with only a  Chung  but minus  a  Chieh. Such months  are made intercalary or leap  months and named after the preceding month with the prefix  Jun  (in Cantonese: Yun) added. It is  quite clear that the Chinese  calendar-makers had firm knowledge of the Metonic  Cycle. 

Resonance periods  arise from the fact  that although the motions of the sun, moon, and planets are incommensurable, they fall into approximate harmony after certain  periods, the most useful of which is a cycle of  nineteen  years  which almost  exactly  equals  two hundred thirtyfive lunations. In each nineteen years,  the Chinese  calendar contains seven intercalary or leap months. In  China this  cycle is called  Chang  or a chapter, and it is still the most convenient period for studying the relationship between the lunar and solar calendar.

The Chinese calendar is  the longest unbroken sequence of time measurement in history. The traditional Chinese year is calculated according to a solar formula  but fitted into a lunar calendar to  make it a lunisolar calendar, the important events  of  the year are always fixed according to the traditional calendar; the festivals, religious and ritual days and the organization of fishing and agricultural activities. The first calendar, according to the  Shih-chi  or  Historical  Records written about 90 B.C., is attributed to  Huang-ti  or the Yellow Emperor,  2697 B.C., who orders the study of  the stars by the astronomers  at his court. It was his minister  Ta Nao  who prepared the first calendar called  Kan-chih  or Chia-tzu  system which Western scholars  have  translated as  ‘the system of cyclical characters’. The  Kan-chih  system of reckoning dates is by combining each of the ten ‘stems’ with each of the twelve ‘branches’ in pairs, with the ‘stem’ being always  on top of the ‘branch’. Beginning with  Chia-tzu  (1 and 1 each series), and then  I-ch’ou  (2 and 2), thereafter continuing through  Kuei-yu  (10 and 10), to  Chia-hsu  (1 and 11),  I-hai  (2 and twelve) and then  Ping-tzu  (3 and 1) and permuting in the same manner.  It will take sixty  permutations to complete a cycle, ending in  Kuei-hai  (10 and 12) before  Chia-tzu  (1  and  1), the first pair reappears.  The Chinese call this cycle  Liu-shih-kan-chih  or  Liushih-hua-chia-tzu  and oftentimes abbreviated as  Hua-chia. The Chinese sexagesimal cycle can be  thought of in the image of two enmeshed cogwheels, one having twelve and the other ten teeth, so  that not until sixty combinations have been made  will the cycle reappear. Again, as the system was intended  for popular use, so that the meanings were to be familiar to the people at large; another phase was introduced. 

The twelve earthly branch  characters  each  came  to  be associated with  a particular animal sometime during the late  Chou  period. These are Rat, Ox, Tiger, Hare, Dragon, Serpent, Horse, Sheep, Monkey, Cock  ,Dog and Boar. These twelve  animals were classified as  Shih-erh sheng-hsiao  or commonly called the twelve  Zodiac Animals by Westerners. They are merely popular symbols for the illiterate  and do not have any great significance or meaning. The Chinese calendar was formalized  by  Emperor Yu which is  know as  Hsia-cheng. The term,  Cheng, means ‘proper’, but  in calendar-making, Cheng  month means the first month of the year. Later when the Shang dynasty overthrew the Hsia, it changed the Cheng to the Ch’ou month, the one preceding the Yin month..  After the Chou dynasty defeated the Shang, it named for its  Cheng, the  Tzu  month. The  Hsia-cheng  is much more  convenient  to an agrarian nation such as China. Counting from the  Yin  month, the first month three months, following the true course of nature, actually formed the  spring season; the next three months, summer; the third  three months, autumn; and the last three months, winter. It was  not until the year 104 B.C.  that  Wu-ti of the Han dynasty abolished the difference by restoring the  Hsia-cheng,  that is, by restoring the  Yin  month officially as the first month of the year – a system which has been followed up to the present times.  Therefore, in modern times  the Chinese calendar is often referred to as Hsia-li or the Hsia calendar.