《宋書·五行志》日食紀事探源

Tracing the Sources for the Solar Eclipses in the“Treaties on the Five Phases”in the Songshu

中古史書的《天文》《五行》等志中包含有豐富的天象紀事,描述某一時間一個或多個天體所呈現的特殊視覺形態或位置關係。這些天象紀事通常附有與之相配合的占辭和事應。占辭對天象徵兆意義做出解讀,事應則列舉應驗徵兆解讀的政治事件。以往對此類材料的研究和利用,可以分爲兩大類。第一類是將史書中的天象紀事看作古人留下的觀測數據,加以分析,用來探索超新星遺迹、地球自轉的長期變化等現代科學問題,或是爲天文學史的基礎研究提供證據^([1])。第二類是將天象及其占驗用作政治史的素材,研究政治勢力如何藉助天文徵兆,進行政治宣傳和合法性的論述^([2])。

“Treaties on Astrology” 天文志 and“Treasties on the Five Phases” 五行志 and the like in medieval Chinese historical works commonly include rich accounts of astronomical events,including solar eclipses.Historians have strongly believed in the authenticity of these accounts as results of continuous observation and record-keeping.Some eclipses are identified as not observable in China and thus must have been noted down based on calculation.They have been understood as mostly prediction results that were kept together with observational records.By testing unobservable and other suspicious eclipse jottings,dated to the third through the fifth centuries and found in the“Treaties on the Five Phases”in the Songshu 宋書,against reenacted calculations using procedures found in the three major calendars in the same period,one discovers that these eclipses were most probably calculated by the Daming Calendar 大明曆 composed in 462.That means they were not predictions that had been handed down,but were computed backwardly by later astronomers and historians.One further finds out that some items were misplaced in time,usually by a year,in the process of the retrospective calculation.These discoveries urge historians and critical editors to reevaluate the nature of astronomical content in medieval Chinese histories and to update the methods for working on accounts of celestial events in those texts.