Chinese lunisolar calendar

Chinese lunisolar calendar

The Chinese lunisolar calendar is a traditional calendrical system originating in Ancient China that synchronizes lunar months with the solar year for civil, agricultural, and ritual purposes. It has been used by dynasties such as the Zhou dynasty, Han dynasty, Tang dynasty, and Ming dynasty and influenced calendars in Korea, Japan, and Vietnam. The calendar underpinned timing for institutions like the Imperial examination and events such as the Spring Festival and the Mid-Autumn Festival while interacting with astronomical practices from observatories in Chang'an, Kaifeng, and Beijing.

History

The calendrical tradition grew during the Warring States period and was formalized under rulers such as Qin Shi Huang and advisers like Lü Buwei and later scholars of the Han dynasty including Liu Xin and Zhang Heng, who advanced astronomy at the Imperial Astronomical Bureau. Reforms by Emperor Wu of Han and legal codifications in the Tang dynasty reflected input from figures such as Li Chunfeng and institutions like the Astronomical Bureau of the Tang. The Song dynasty saw compilations by officials like Shen Kuo and refinements in instruments used at observatories in Kaifeng. The Yongle Emperor of the Ming dynasty sponsored calendar projects linked to the Nanjing and Beijing courts. In the Qing dynasty, the calendar interacted with Jesuit missionaries such as Matteo Ricci and astronomers like Ferdinand Verbiest who advised the Imperial Court and contributed to reforms recorded alongside indigenous scholars like Guo Shoujing. Republican reforms after the Xinhai Revolution and modernization efforts involved intellectuals such as Sun Yat-sen and scientists associated with institutions like Peking University, eventually leading to official adoption of the Gregorian calendar for civil use while the lunisolar system persisted for festivals and agricultural rites.

Structure and components

Months in the system are based on synodic lunar months determined by new moons observed in repositories like the Imperial Observatory (Beijing), producing alternating 29- and 30-day months named numerically (first month, second month, etc.). Years are organized by the sexagenary cycle combining the Heavenly Stems and Earthly Branches, which also link to the Chinese zodiac animals such as Rat (zodiac), Ox (zodiac), and Tiger (zodiac). Solar terms known as the 24 solar terms (e.g., Lichun, Jingzhe, Dongzhi) partition the tropical year and are tied to seasonal markers used by agrarian authorities in regions like the Yellow River basin and the Yangtze River valley. Epochal counts and era names (nianhao) under dynasties like the Han dynasty, Tang dynasty, Song dynasty, and Ming dynasty informed official dating alongside regnal calendars maintained by courts in Chang'an and Nanjing.

Calculation and intercalation rules

Intercalation historically followed rules devised by court astronomers including the use of 19-year Metonic-related cycles in certain periods and empirical corrections from observations by figures such as Zhang Heng and Guo Shoujing. The algorithm balances lunar months with the tropical year using leap months inserted roughly seven times every 19 years; placement depends on the absence of a principal solar term within a lunar month, a rule applied in calculations by staff at the Astronomical Bureau under dynasties like the Qing dynasty and the Ming dynasty. Computational techniques incorporated mean motions cataloged by mathematicians such as Zu Chongzhi and observational data from instruments like the armillary sphere and the gnomon used at imperial observatories. Modern computational reconstructions use astronomical models developed at institutions like Purple Mountain Observatory and universities such as Tsinghua University to produce ephemerides compatible with traditional rules.

Cultural and religious significance

The calendar structures major festivals including Chinese New Year (the Spring Festival), the Lantern Festival, the Dragon Boat Festival, and the Mid-Autumn Festival, and prescribes auspicious and inauspicious days used in traditions like feng shui consultations and rituals performed by temples such as Shaolin Temple and religious communities associated with Taoism, Buddhism in China, and folk worship of deities like Guanyin. It informed agricultural rites tied to dynastic rituals at sites such as the Temple of Heaven in Beijing and seasonal ceremonies conducted by elites including officials from the Ministry of Rites. Folk calendars combining local customs in provinces such as Sichuan, Guangdong, and Yunnan reflect syncretism with practices documented by ethnographers from institutions like the Chinese Academy of Social Sciences.

Regional variations and reforms

Variants developed regionally in Korea (influencing the Korean calendar), Japan (influencing the Japanese lunisolar calendar prior to the Meiji Restoration), and Vietnam (the Vietnamese calendar), each adapting intercalation and epochal reckoning; Japanese reforms under the Meiji Restoration and Korean reforms during the Joseon dynasty illustrate localized standardization. Colonial and missionary encounters with Europeans led to hybrid calculations introduced by Jesuits and later replaced or integrated during reforms by institutions such as the Republic of China government and the People's Republic of China which adopted the Gregorian calendar while preserving lunisolar dates for cultural observance. Contemporary scholarship from historians at Harvard University, SOAS University of London, and Peking University examines archival materials from dynastic courts, while astronomical projects at observatories like Purple Mountain Observatory provide data for retrospective calendrical studies.

Category:Calendars