 | THE HISTORY OF THE FORMER HAN DYNASTY The history of the former Han dynasty |  |
Appendix IV
THE ECLIPSES DURING THE REIGN OF THE EMPEROR
KAO-TSU
During this period of twelve (or fifteen) years, only three eclipses are
recorded. We discuss them in chronological order.
i. In the third year of Kao-tsu's reign, the tenth month, on the day
chia-hsü, a solar eclipse is recorded (1A: 35a). This date was, according
to P. Hoang, Concordance des chronologies néoméniques, chinoise et européenne,
("Variétés sinologiques," no. 29), Shanghai, 1910, (which is used
for dates throughout), December 20, 205 B.C. For that date Oppolzer
calculated his solar eclipse no. 2387. It was merely partial; calculation
according to the method in P. V. Neugebauer, Astronomische Chronologie
(which is used for such calculations throughout), shows that the eclipse
reached a magnitude of 0.51 (the diameter of the sun being 1.00) at
Ch'ang-an at 10:44 a.m., local time.
HS 27 Cb: 13a adds, "It was 20 degrees in [the constellation] Tou,"
whose stars were then in R.A. 241.1° to 253.3°. The sun was in long.
266.0° = 265.6° R.A.[1]
There is thus good agreement in both the date
and location of the sun.
ii. In the third year, the eleventh month, the day kuei-mao, the last
day of the month, a second solar eclipse is listed (1A: 35a). HS 27
Cb: 13a adds, "It was three degrees in [the constellation] Hsü, whose
two stars, α Equulei and β Aquarii, were then in R.A. 291.1° and 293.2°.
This date was Jan. 18, 204 B.C., but there was no eclipse on that date,
for Oppolzer gives none.
The Han-chi (written by Hsün Yüeh, lived 148-209) records the preceding
and the next eclipse (2: 11b, 4: 2a), copying the recording in the
HS, but omits this one, which, in view of the fact that the Han-chi takes
its material mostly from the HS, makes it look as though this eclipse
was not in the text of the HS during the second century A.D. If so, it
was interpolated both into chapters 1 and 27. In view of the fact that
Hsün Yüeh noted all the other eclipses that are in the HS for the first
half century of the Han period, even the one only found in HS ch. 27
(cf. ch. 4, App. IV, vi), it is difficult to explain otherwise his omission
of this eclipse.
During the seven years between the proceeding recorded eclipse and
the next one, there occurred 14 solar eclipses, of which only one was
Oct. 8, 201 B.C., which was in the sixth year, eighth month, on the
last day, kuei-wei (if Hoang's calendar is one day in error). Oppolzer
calculates the sun in long. 191.6° = 190.7° R.A. The magnitude
of this eclipse was calculated for Ch'ang-an and was found to have
reached only 0.02, at 7:44 a.m. local time, so that it was practically
invisible there; at the present Pei-p'ing its magnitude however reached
0.28 at 8:26 a.m., local time, so that this eclipse might have been
reported from the east. Oppolzer's solar eclipse no. 2400, on Aug. 18,
199 B.C. seemed also visible in China, but calculation showed that it
was invisible in any part of China and even in the present Canton.
The eclipse of 201 B.C. might have been the one intended by this
recording, although it is not easy to explain the discrepancy of the
cyclical day. The SC does not record any of the three eclipses that the
HS lists in the reign of Kao-tsu. Pan Ku thus inserted them into the
account of events given in the SC from some other source. Some astronomer
who edited the list of eclipses thus used by Pan Ku might have
given an illegibly dated eclipse the next possible date for an eclipse after
the first and legibly dated solar eclipse. But two solar eclipses at successive
new moons can happen only when two small eclipses occur in
different (northern and southern) hemispheres.
Since however the Han-chi does not have this eclipse, it seems more
likely that some person of the third or later centuries interpolated this
eclipse for a time when he knew that an eclipse might have happened,
in order to emphasize the gravity of the period. In June/July of this
year, Kao-tsu barely escaped with his life from the siege of Jung-yang.
The location in the heavens given for this eclipse does not agree with
anything we can calculate. It must have been calculated from the date
of the year given to this eclipse, for it is about 28 Chinese degrees after
the preceding one.
iii. In the ninth year, the sixth month, on the day yi-wei, the last day
of the month, a third solar eclipse is recorded (1B: 14b). This date was
Aug. 7, 198 B.C.; Oppolzer calculates his solar eclipse no. 2402 for that
date. HS 27 Cb: 13a adds, "It was 13 degrees in [the constellation]
Chang," whose stars then ranged from 118.6° to 133° R.A. Oppolzer
calculates the sun as at long. 129.4° = 131.9° R.A. There is thus a
very close checking between observation and calculation here.
Since Chinese astronomical data were always referred to the equator, not the ecliptic,
celestial positions must be reduced to right ascension for purposes of comparison.
Besides those whose location Oppolzer charts, the following three partial eclipses
were invisible because they belong to initial (i.) or terminal (t.) runs in exeligmos series
whose nearest umbral eclipse was located near the south pole: no. 2389 (i.); no. 2390
(t.); and no. 2398 (t.). In addition two partial eclipses were visible in the northern
hemisphere, both of which were invisible in China: (1) no. 2388, on May 17, 204 B.C.;
calculation shows that this eclipse was invisible; (2) no. 2397, on Mar. 4, 200 B.C.; calculation
shows that at lat. 40°N it was visible only in the Atlantic Ocean and Europe.
| THE HISTORY OF THE FORMER HAN DYNASTY The history of the former Han dynasty | |