Publ. Astron. Obs. Belgrade No. 86 (2009), 355 - 360 Poster THE CHINESE CALENDARS N. KOSTI ´ C 1 and S. ˇ SEGAN 2 1 Confucius Institute, Studentski trg 12, 11000 Belgrade, Serbia E–mail: natasa kostic@yahoo.com 2 Mathematical Faculty, Department of Astronomy, Studentski trg 16, 11000 Belgrade, Serbia E–mail: ssegan@matf.bg.ac.yu Abstract. In this article we try to answer the question how and why did Chinese ancient astronomy came into being and how did one lonesome and original calendar system on the very end of the world develop. At the beginning, Chinese people distinguished time of the year by the annual cycles of plants and animals, but soon began to determine seasons by observing celestial bodies. Early successful measuring of tropical year and synodic month made possible for Chinese people to issue first calendars very early. Spring and Autumn (Chunqiu) period (770 - 476 BC) brought forward first official cal- endars. Further improvement of calendars is due to the development of new astronomical instruments. Chinese calendars also originate from the metaphysical concepts of Qi, Yin-Yang and 5 elements. 5 elements were connected with Chinese 5 seasons of the year and this was the first form of solar calendar. Later, it developed into solar calendar with 10 months. In the next phase, Chinese calendar turned into lunisolar calendar which also has its evolution. Chinese people invented Calendar ”with division by four” (the name of this calendar). They also added 24 solar terms to make calendar harmonize with natural cycles. Li Chunfeng rearranged intercalations and used month without main solar term and divided months into short and long months. Sexagesimal system of time measuring refers to the system of Chinese 10 Heavenly Stems and 12 Earthly Branches. Its purpose is to measure time and define years, months, days and hours. 1. INTRODUCTION This article contains a brief survey of principal calendrical rules, and of the history and significance of the Chinese calendars, as an example of general systems of organizing units of time for the purpose of reckoning time over extended periods. At first, we must notify implicit convention: the day is the smallest calendrical unit (of time). The measurement and summarizing of fractions of a day are classified as timekeeping and time scales building. The generality of this definition is due to the diversity of methods that have been used in creating calendars and technology of timekeeping. Although many of significant calendars replicate astronomical cycles according to recognizable eternal or cyclic rules, others are based on abstract, perpetually repeating 355