East Asia has a rich tradition of astronomical observation. Until the nineteenth century, the chief calendars in use in the region were derived from the Chinese. To this day, traditional calendars are used to mark religious and traditional festivals and holidays; the Gregorian calendar regulates civic affairs.
The Chinese Calendar
The beginnings of the Chinese calendar are steeped in legend; it is said that the legendary emperor Huangdi created it in 2637 BCE. Evidence for the calendar can be traced back to the fourteenth century BCE. In effect, it is a lunisolar calendar, 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 that the sun reaches its most northerly point in the sky), and its months concur with the synodic months (the period between two successive full moons or two conjunctions of the sun and moon). In the Chinese calendar as in the Jewish, an ordinary year has twelve months, while a leap year has thirteen months. An ordinary year has 353, 354, or 355 days, and a leap year has 383, 384, or 385 days.
In order to arrive at a Chinese year, the dates of the new moons are determined. A new moon is construed as the completely "black" moon (when the moon is in conjunction with the sun), not the first visible crescent as stipulated in Jewish and Islamic calendars. The date of the new moon is the first day of a new month. Next, the dates when the sun's longitude is a multiple of 30 degrees are calculated. These dates are known as the Principal Terms and 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, which approximately matches the east coast of China. Unlike other calendars, the Chinese calendar does not count years in an infinite sequence. Instead, years have names that are repeated every sixty years. Within a given sixty-year cycle, each year is assigned a name made up of two parts: the Celestial Stem, whose terms cannot be translated into English, and the Terrestrial Branch, whose terms correspond to animals of the Chinese zodiac. This method of using a sixty-year cycle is ancient; the sixty-year cycles are numbered from 2637 BCE, when the Chinese calendar is said to have started.
The Japanese Calendar
The Japanese calendar is similar to the Chinese, given the many cultural exchanges between the two nations, and is said to date from 660 BCE, from the reign of the emperor Jimmu, the legendary first emperor of Japan. In China and elsewhere, the calendar was used to count the passage of time, but in Japan, the reckoning of time as such had little importance. The Japanese used the Chinese sixty-year cycle for naming days and years, with each day being determined as "good" or "bad." Side by side with this practice, by 807 CE, a seven-day week, with names related to the planets, was also in use, although the need to know "good" or "bad" days continued. By 1007, the seven-day week was common in Japan.
Little attention was paid to the calendar as a means of reckoning time until 1684, when three Japanese astronomers (Harumi Shibukawa, Anbu Yasutomi, and Jinzan Tani) advocated calendrical reform. However, their efforts met with little success, since the ruling elite was more interested in astrology and mystical interpretations of the days of the week than in precise timekeeping. The three reformers labored on in isolation, completely unaware of the advances being made by the Chinese with the aid of Jesuit missionaries. Only in the Meiji period (1868–1912) did Japan finally use a consistent and relatively accurate method for recording time, with the adoption of the Gregorian calendar. However, the old associations intrinsic to Japanese culture remain, such as the determination of festivals, the naming of years after the current emperor, and the significance of astrology and the zodiac.
The Korean Calendar
As with Japan, the source of the Korean calendar is China. The Korean calendar was not merely a method of keeping time, it was also an expression of divine will in that, as in Japan, it was used to determine "good" and "bad" days. It was the responsibility of the king to maintain an annual calendar. The Korean calendar served as an astronomical almanac, predicting the movements of the sun, moon, and five visible planets over the course of the year. These predictions then allowed court astrologers to determine "good" or "bad" days.
One of the first recorded Korean calendars is the Tai Chu calendar, which was created by Hong Loxia during the reign of emperor Wu (156–86 BCE) of the Han dynasty (206 BCE–220 CE), who had incorporatedPage 396 | Top of Article Korea into China. Given the use of the Chinese ephemeris (a table of locations of heavenly bodies), many errors had crept into the Tai Chu calendar by the time of the Northern Song (960–1126) and the Southern Song (1127–1279). These inaccuracies necessitated calendrical reform during the reign of Khubilai Khan (1215–1294), who reconquered Korea, and again under the first Ming emperor, Hongwu (1328–1398), who also ruled over Korea. Finally, Kim Yuk (1580–1658), a Korean official, strongly advocated calendrical reform using Gregorian calculations. He was following the lead of China, which had adopted the Western methodology under the guidance of Johann Adam Schall von Bell (1591–1666), a German Jesuit missionary and astronomer, at the beginning of the Qing dynasty (1644–1912).
But it would be another century before Korea finally adopted Gregorian principles and established the new Shixian calendar. However, this adoption met fierce resistance in the character of Yi Hangno (1792–1868), a scholar who defended traditional ways against innovations from the West. Yi Hangno argued that although the Western calendar was accurate and precise, it failed to fulfill the traditional role of a calendar in Korean society, namely, the determination of sacrificial rites, rituals for the end of the year, marriage rites, daily tasks, and monthly recitations. In short, the Gregorian calendar destroyed Confucian ritual, ethics, and philosophy. However, once Gregorian principles were established, there was no going back to the old ways.
Ho, Peng Yoke. (1977) Modern Scholarship on the History of Chinese Astronomy. Canberra, Australia: Faculty of Asian Studies, Australian National University.
Miller, Lyman. (2000) "Korea's Encounter with the West." Course reading for Stanford University history course 92a, Roots of Modern East Asia. Retrieved 22 April 2002, from: http://www.stanford.edu/class/history92a/readings/Kencounter.html .
Pannekoek, Anton. (1961) A History of Astronomy. London: G. Allen & Unwin.
Reingold, Edward, and Nachum Dershowitz. (2001) Calendrical Calculations. New York: Cambridge University Press.
Sugimoto, Masayoshi, and David L. Swain (1978) Science and Culture in Traditional Japan, A.D. 600–1854. Cambridge, MA: MIT Press.