This Qing dynasty illustration shows yet another version of the calendar-creation legend. In this legend the Xi and He brothers receive a government commission from emperor Yao to organize the calendar with respect to the celestial bodies.
The ancient Chinese calendar is still used to mark religious and traditional holidays and festivals. Its form is derived from astronomical observations of the longitude of the sun and the phases of the moon. Unlike other calendars, it does not count years in an infinite sequence.
China has a long tradition of astronomical observation. The main calendars used in the Far East were Chinese in origin until the nineteenth century; today such long-established calendars still are used to mark religious and traditional holidays and festivals; the Gregorian calendar regulates only civic affairs.
The origin of the Chinese calendar is steeped in myth; the legendary Emperor Huangdi supposedly created the calendar in 2637 BCE. But historical evidence dates the invention of the calendar well into the fourteenth century BCE. Its form is lunisolar (derived from astronomical observations of the longitude of the sun and the phases of the moon), therefore its year matches the tropical year (the period between two successive times when the sun reaches its most northerly point in the sky), and its months coincide with the synodic months (the period between two successive full moons or two conjunctions of the sun and moon).
An ordinary year in the Chinese calendar, as in the Jewish, has twelve months, whereas a leap year has thirteen months. As a result, an ordinary year has 353, 354, or 355 days, and a leap year has 383, 384, or 385 days.
To determine the Chinese year, first the dates of the new moons are established. A new moon is interpreted as a completely “black” moon (when the moon is in conjunction with the sun), not the first visible crescent, as stipulated in Islamic and Jewish calendars. The date of a new moon is the first day of a new month. Calculated next are the dates when the sun’s longitude is a multiple of 30 degrees. These dates, called the “principal terms,” are used to calculate the number of each month. Therefore, each month carries the number of the principal term that occurs in that month.
All astronomical observations are made for the meridian 120 degrees east of Greenwich, England, which approximately aligns with the east coast of China. The Chinese calendar, unlike other calendars, does not count years in an infinite sequence. Instead, years have names that are repeated every sixty years. Within a sixty-year cycle each year is assigned a name composed of two parts: the celestial stem, the terms of which cannot be translated into English, and the terrestrial branch, the terms of which correspond to animals of the Chinese zodiac. This method of using a sixty-year cycle is ancient: The cycles are numbered from 2637 BCE, when the Chinese calendar supposedly was established.
Ho Peng Yoke. (1977). Modern scholarship on the history of Chinese astronomy. Canberra: Faculty of Asian Studies, Australian National University.
Pannekoek, A. (1961). A history of astronomy. London: G. Allen & Unwin.
Reingold, E., & Dershowitz, N. (2001). Calendrical calculations. New York: Cambridge University Press.
An inch of time is an inch of gold, but an inch of time cannot be purchased for an inch of gold.
Yí cùn guāng yīn yí cùn jīn, cùn jīn nán mǎi cùn guāng yīn
Source: Dass, Nirmal. (2009). Calendar. In Linsun Cheng, et al. (Eds.), Berkshire Encyclopedia of China, pp. 259–260. Great Barrington, MA: Berkshire Publishing.
Calendar (Yīnlì 阴历)|Yīnlì 阴历 (Calendar)