Encyclopedia of India–China Cultural Contacts v1.c6.22

v1.c6.22

Contents related to “lunar month” of ancient Indian seasons and calendars are also recorded in translated *sutras* which are rich in detail and include division of season, month names, concepts of white month and black month, arrangements of large month and small month, placement of leap month, changes in day and night time-length, division and name of day and night time etc. The Volume 48 of *Da zhi du lun* (*Great Treatise on the Perfection of Wisdom*) defines four kinds of months, which are so-called “solar month”, “*karma* month”, “lunar month” and “*nakshatra* month”. Here, the “solar month” is one-twelfth of the length of a tropical year, “*karma* month” is one-twelfth of an ideal year (which consists of 360 days), “lunar month” connotes synodic month and “*nakshatra* month” refers to sidereal month. Several forms of seasonal changes in the length of shadow at noon are given in sutras. Datasheets in *Shi fei shi jing* (*Sutra on Time and Non-Time*) are most detailed. As for complete books similar to ancient Indian calendars, besides the Jiuzhi Calendar, the Futian Calendar can be considered as representative. It originated from Indian astronomy and was popular among the Chinese during the late Tang Dynasty. Its main contents are however now untraceable. According to the inference of Sou Neiqing, the Guangzhai Calendar compiled by Gautama Luo might be “a kind of astronomical almanac calculating astronomical phenomena based on Indian astronomy.”