Abstract

The system of today’s sexagenary cycle‒based year calendar was not in good order from the beginning, and there had been various calendar systems until Chin and Han(秦漢). At the end of Former Han, Liu Xin(劉歆) found that the actual cycle of revolution of Jupiter was 11.86 years, which led to the implementation of a chao chen(超辰)‒based calendar system. There was, however, inconvenience with its actual application. Thus they started to mark the number of years according to the order of 60‒sexagenary cycle based on the 60‒year‒period of Great Conjunctions of Jupiter and Saturn regardless of the run of Jupiter. That was the sexagenary cycle‒based calendar system. It was only after the implementation of Sifen Calendar(四分曆, the quarter remainder calendar) in A.D. 85 during Latter Han that the system became generalized. As for the first month of the year that was the starting point of a year, there was a revision to Taichu Calendar(太初曆, the beginning calendar) in B.C. 104 during the reign of Emperor Wu(武帝) of Han, which led to the fixation of winter solstice in November and the reform that made the onset of spring, which was the exact middle point between winter solstice and vernal equinox, the beginning of a year. Since then, the starting point of a year by the standard of In(寅) month(建寅歲首) has been implemented according to the first month of the year of Xia dynasty except for certain periods. The implementation of the starting point of a year by the standard of In(寅) month was hugely influenced by the establishment of Wu‒Xing‒Xiang‒Sheng‒Shuo that began with wood[spring]. There is a symbolic explanation that the origin of calendar of sexagenary cycle‒based calendar was when the seven luminaries of sun, moon and the five visible planets were arranged in a straight line in the northern celestial sphere or during 4 Gapja(甲子). The actual calendar, however, has a couple of different origins of calendar of Gapin(甲寅). A good example is that the origin of calendar of Taichu Calendar(太初曆) is Gapin(甲寅) year, Gapja(甲子) month, Gapja(甲子) day, Gapja(甲子) hour according to the sexagenary cycle‒based expressions. The first year of Taichu was B.C. 104(丁丑, Jeongchuk) but the zero year of Taichu that was the standard of Taichu Calendar(太初曆) was B.C. 105, a year of Byeongja(丙子). It was changed to a year of Gapin(甲寅) through Taichu revision of the origin of calendar(太初改元). However, the origin of calendar was revised as B.C. 161(庚辰, Gyeongjin) through Sifen Calendar(四分曆) in A.D. 85, and the changed title has been in use since then.