eclipse Literary and historical referencesastronomy

According to long-established tradition, the history of astronomy in ancient China can be traced back before 2000 bc. The earliest relics that are of astronomical significance date from nearly a millennium later, however. The Anyang oracle bones (inscribed turtle shells, ox bones, and so forth) of the latter part of the Shang dynasty (c. 1600–1046 bc), which were uncovered near Anyang in northeastern China, record several eclipses of both the Sun and the Moon. The following report is an example:

On day guiyou [the 10th day of the 60-day cycle], it was inquired [by divination]: “The Sun was eclipsed in the evening; is it good?” On day guiyou it was inquired: “The Sun was eclipsed in the evening; is it bad?”

The above text provides clear evidence that eclipses were regarded as omens at this early period (as is true of other celestial phenomena). Such a belief was extremely prevalent in China during later centuries. The term translated here as “eclipse” (shi) is the same as the word for “eat.” Evidently the Shang people thought that a monster actually devoured the Sun or Moon during an eclipse. Not until many centuries later was the true explanation known, but by then the use of the term shi was firmly established to describe eclipses, and so it remained throughout Chinese history. The oracle-bone text, translated above, twice gives the day of the sexagenary cycle; this cycle, which was independent of any astronomical parameter, continued in use (seemingly without interruption) until modern times. Nevertheless, as the year in which an eclipse occurred is never mentioned on the preserved oracle bones (many of which are mere fragments), dating of these observations by astronomical calculation has proved extremely difficult. In general, Shang chronology is still very uncertain.

The Shijing (“Classic of Poetry”) contains a lamentation occasioned by an eclipse of the Moon followed by an eclipse of the Sun. The text, dating from the 8th century bc, may be translated:

The Sun was eclipsed, we found it greatly ominous…that this Moon is eclipsed is but an ordinary matter; but that this Sun is eclipsed—wherein lies the evil?

The different attitudes toward solar and lunar eclipses at this time is interesting. Throughout the subsequent 1,000 years or so, lunar eclipses were hardly ever reported in China—in marked contrast to solar obscurations, which were systematically observed during much of this period. The earliest of these observations are recorded in a chronicle of the Chinese state of Lu (now in Shandong province), the birthplace of Confucius. This work, known as the Chunqiu (“Spring and Autumn [Annals]”), lists many solar eclipses between 722 and 481 bc. On three occasions the Chunqiu describes eclipse ceremonies in which drums were beaten and oxen were sacrificed. Further, three eclipses (occurring in 709, 601, and 549 bc) were described as total. The earliest of these, that of July 17, 709 bc, is recorded as follows:

Third year of Duke Huan, 7th month, day renchen [the 29th day of the cycle], the first day of the month. The Sun was eclipsed and it was total.

This is the earliest known record of a total solar eclipse from any civilization. Computation shows that this eclipse was indeed total at Qufu, the Lu capital.

From about 200 bc (following the unification of China into a single empire), a wide variety of celestial phenomena began to be noted on a regular basis. Summaries of these records are found in astronomical treatises contained in the official histories. In many instances, a report is accompanied by a detailed astrological prognostication. For example, the Houhanshu (“History of the Later Han Dynasty”) contains the following account under a year corresponding to ad 119–120:

On the day wuwu [the 55th cyclical day], the 1st day of the 12th lunar month, the Sun was eclipsed; it was almost complete. On the Earth it became like evening. It was 11 deg in the constellation of the Maid. The woman ruler [i.e., the empress dowager] showed aversion to it. Two years and three months later, Deng, the empress dowager, died.

The date of this eclipse is equivalent to Jan. 18, ad 120. On this exact day there occurred an eclipse of the Sun that was very large in China. The above-cited text is particularly interesting because it clearly describes an obscuration of the Sun, which, though causing dusk conditions, was not quite total where it was seen. With regard to the accompanying prognostication, it should be pointed out that a delay of two or three years between the occurrence of a celestial omen and its presumed fulfillment is quite typical of Chinese astrology.

Systematic observation of lunar eclipses in China began around ad 400, and from this period onward the official astronomers often timed the various phases of both solar and lunar eclipses with the aid of clepsydras (water clocks). Chinese astronomical techniques spread to Korea and Japan, and, especially after ad 1000, eclipses were regularly observed independently in all three countries. However, the Chinese records are usually the most detailed.

The following account from the Yuanshi (“History of the Yuan Dynasty”) of the total lunar eclipse of May 19, ad 1277, follows the customary practice of quoting timings in double hours (12 to a combined day and night) and marks (each equal to ¹/₁₀₀ of a day and night, or 0.24 hours):

14th year of the Zhiyuan reign period, 4th month, day guiyou [the 10th cyclical day], full Moon. The Moon was eclipsed. Beginning of loss at 6 marks in the hour of zi; the eclipse was total at 3 marks in the hour of chou; maximum at 5 marks in the hour of chou; reappearance of light at 7 marks in the hour of chou; restoration to fullness at 4 marks in the hour of yin.

The three consecutive double hours zi, chou, and yin correspond, respectively, to 11 pm to 1 am, 1 am to 3 am, and 3 am to 5 am. The measured times are equivalent to 12:34 am (start of eclipse), 1:50 am (beginning of totality), 2:19 am (mid-eclipse), 2:48 am (end of totality), and 4:05 am (end of eclipse).

From the 3rd century ad onward, there is evidence of attempts at predicting eclipses by Chinese astronomers. Crude at first, these predictions reached their peak accuracy near the end of the 13th century, with typical timing errors of about one-fourth of an hour.