The European Influence on Japanese AstronomyHideo Hirose

In 554, during the regime of Emperor Kimmei, a scholar versed in the knowledge of the calendar came from Paekche to Japan on Japan’s request. His arrival marked the beginning of the importation of knowledge concerning the astronomical calendar. Later in 602, during the regime of Emperor Suiko, a Buddhist priest from Paekche named Kanroku came to Japan and brought with him books on the calendar and astronomical geography. Kanroku’s assistance extended also to the instruction of Japanese students. It is assumed that the calendar Kanroku introduced was the Chinese calendar Yüan-chia-li. From this time until the beginning of the Tokugawa regime, Japan used only Chinese calendars without any revision. Besides the Yüan-chia-li the following four calendars were adopted in turn: the I-feng-li, the Ta-yen-li, the Wu-chi-li, and the Hsüan-ming-li. The Hsüan-ming-li, after its adoption in 862, was used for 823 long years. This is a clear indication that Japanese scholars were incapable of revising their calendars.

During these long centuries, however, the Indian or Buddhist astronomical calendar was also introduced, although it was never used as a national calendar. Since it contained a type of horoscope exactly the same as that used in the West, we can consider this calendar as a Western influence, albeit an indirect one. Direct cultural exchange in the astronomical field did not begin until the opening of intercourse with the Iberian Peninsula.