Empirical Studies in Ancient Chinese Astronomy 华夏古天文历法实证研究

This thread—Empirical Studies in Ancient Chinese Astronomy and Calendrics—asks one question: among the records of ancient Chinese astronomy and calendrics, which can be checked and which cannot. It is arranged as question → material → the limits of the conclusion, not by date of writing.

相关 / Related：入门指南 ｜ 基础知识 ｜ 历法改革

1 · What this line of research asks

This line of research confines the word “empirical” to a narrow range: a judgement counts as empirical only when it can be tied to material that is observable, checkable and comparable; anything beyond that range is marked as inference.

The starting point is a plain question. With a star chart in every pocket, why look back at what the ancients wrote down? For them the sky was an institution: the calendar was the state’s public clock, the stars were the paperwork of political legitimacy, and portents were among the few soft restraints on a ruler. Revising a calendar could stir finance, ritual, imperial authority and scholarship at once. To look back at that sky is to look at the people who wrote the stars into institutions.

2 · Two legs: transmitted texts and excavated material

Transmitted texts supply the skeleton, and a skeleton may have been reassembled by later hands. The clearest case is the Ganshi Xingjing: the name sounds like the original work of Gan De and Shi Shen in the Warring States, but the text was long ago lost, and what survives is mostly quotations copied from one encyclopaedia or prognostication manual to the next after the Tang and Song, expanded or attributed by later hands. By contrast the value of the Kaiyuan Zhanjing lies precisely in its refusal to create: Gautama Siddha copied whole passages out of works now lost, with their sources noted, and so it became a traceable quarry.

Excavated material serves as an X-ray of that skeleton. The lacquer chest from the tomb of Marquis Yi of Zeng (around 433 BCE) carries the names of the twenty-eight mansions in red, with the Azure Dragon and White Tiger beside them; the silk manuscript Wuxing Zhan from Mawangdui gives the synodic periods of the five planets; the day-books from Shuihudi and Fangmatan show how calendar days were used at the lower levels of society; the calendar tables and duty logs among the Han slips from Juyan and Dunhuang are first-hand evidence for how the Han calendar actually ran. Walking on two legs matters because each corrects the other: excavated material can puncture later embellishment in transmitted texts, and transmitted texts can give context to scattered surviving slips.

3 · The limits of the empirical

Some things the material itself will not let us confirm. This line of research therefore keeps four standing limits:

Silence is not absence. Not finding a certain kind of record in a period shows only that none has been found yet; it does not show that none existed. Archaeology samples; it does not take a census.

The world of meaning in astrology cannot be tested. One can check whether an eclipse really happened and whether it was really recorded; one cannot check what the “the ruler has cause for concern” read out of it meant to those who wrote it. That belongs to intellectual history, and astronomy cannot reach it.

Back-calculation has hard limits. Running modern celestial mechanics backwards three thousand years must handle the accumulated error from the long-term change in the Earth’s rotation; for the same eclipse, the computed time and the zone of visibility may differ by tens of minutes and hundreds of kilometres. Ancient records also often carried political purposes: good news recorded, bad news dropped, entries written after the fact, copying errors.

Falsification is far stronger than confirmation. This is the methodological floor of the whole line: one can say with confidence that a claim cannot hold, and can rarely say that a claim must hold.

4 · Related articles on this site, in reading order

1. Prologue · Between Looking Up and Looking Down: The Origin of an Empirical Study of Ancient Chinese Astronomy and Calendrics —— with star charts in every pocket, why look back at what the ancients wrote down; the question this collection asks and the material it draws on.
2. 001 · The Four Fixed Stars of the Yaodian: A Set of Numbers That Will Not Agree —— the four stars of the Yaodian set against the commentaries and against modern precession, and why the numbers will not agree.
3. 002 · The Verifiability of the Oracle-Bone Records of 「日有食之」 —— a record-by-record listing of the eclipse inscriptions on oracle bones, saying which can be checked against astronomical computation and which cannot.
4. 003 · Twenty-Eight Mansions on the Lacquer Box from the Tomb of Marquis Yi of Zeng: A Lower Bound for the Four Images —— which end of the “four images” a single excavated object can pin down; three layers, each with its own terminus ante quem.
5. 004 · The Gnomon and the Sun at Its Utmost: An Empirical Tradition of Shadow-Measurement before the Dengfeng Observatory —— one pole, one shadow, read for two different things; and how repeated “sun at its utmost” readings yield a year of 365.25 days.
6. 005 · The Zhuanxu Calendar and the Archaeological Evidence for the Calendars of Qin and the Early Han —— three written lines read against three excavated calendar tables, to see how far the calendars of Qin and the early Han can be pinned down.

5 · Why this line deserves separate treatment

Read the six pieces and one thing becomes clear: what this line can supply is mostly not “the ancients were right” or “the ancients were wrong”, but “this statement can be checked this far”. On the same body of material, more can be punctured than can be pinned down—which is the floor this series sets for itself: falsification is stronger than confirmation.