The adoption and evolution of eclipse diagrams in official eclipse forecast reports in late Ming and early Qing China

Geometrical diagrams have been widely used in European astronomy since ancient times, but were largely absent in traditional Chinese astronomy. This situation changed significantly with the introduction of European astronomy into China by the Jesuits in the late Ming and early Qing dynasties (Ming 明, 1368–1644; Qing 清, 1644–1911). Taking eclipse diagrams in official eclipse forecast reports—one of the focal areas of interest at that time—as a case study, this article demonstrates how, owing to their visual clarity, they began to be incorporated regularly into official eclipse forecast reports after 1629 and became a mandatory component by at least 1686. In this process, eclipse diagrams evolved from an initial style closely resembling those in Tycho Brahe’s (1546–1601) Astronomiae Instauratae Progymnasmata to a form more aligned with Chinese requirements. Subsequently, they underwent further modifications, ultimately reaching a standardized form in the early Qianlong period (乾隆, r. 1735–1796). Since eclipses held multifaceted significance in China, these modifications were not purely technical issues but were deeply intertwined with broader considerations, particularly political ones, and eclipse diagrams thus became a political tool employed by the Qing emperors in both domestic governance and diplomatic relation with Korea.