A STUDY OF CORRELATION BETWEEN HISTORICAL ASTRONOMICAL RECORDS AND POLITICALEVENTS1

Hong-Jin Yang
Korea Astronomy and Space Science InstituteAbstract
We study the correlation between distributions of astronomical records and historical events using
historical meteor (shower) records. Planets and meteor (shower) records are the most abundant
astronomical phenomena in Korean, Chinese and Japanese chronicles. And they represent a
general tendency of the number distribution of whole astronomical observations. Thus, weexamine the correlation for the number distribution between meteors (showers) and planetsduring A.D. 1200-1700 and find that both records have a similar distribution. We classify historicalevents into three grades according to the social impact, and investigate the correlation between
distributions of meteor (shower) records with social events, such as, new King's accession to thethrone, foreign invasions, and domestic turmoils. From the statistical analysis, we cannot find any
correlation between the meteor (shower) records and the political events. Therefore, we conclude
that Korean historical records have not been influenced by the political events. We also examine
the correlation between Chinese and Japanese meteor (shower) records and political events forA.D. 1200-1700, respectively, but cannot find any correlations between them.

I.

Introduction

Korea has a long history of astronomy and remains various and amount astronomical relics.
Astronomical observation is one of the most valuable heritages in Korean historical astronomy.
Korean historical observations are mainly recorded in representative history books such as1

The original paper was published in Publications of the Korean Astronomical Society.

(Yang & Choi, 2012, PKAS, 27, pp.411-418)

Samguksagi(三國史記 ), Goryeosa(高麗史 ), and Joseonwangjosillok(朝鮮王朝實錄 ), and they cover234

about 15-30% of the total articles. Astronomical observations were carried out by royal
astronomers systematically over two thousand years in Korea (Jo 1998; Lee 2008). Moreover, royal
astronomers observed astronomical phenomena at the royal observatory in each capital ofdynasty. Since astronomers were special profession who can calculate astronomical bodies, they
were reemployed by new dynasty at the royal observatory when a dynasty replaced by new one.
Therefore, observational terminology and description of the phenomena are consistent inrecording in Korean chronicles. There are many astronomical phenomena in the history books
such as solar(lunar) eclipse, two of three Suns appeared together, Venus seen at daylight, comet,meteor, guest star, aurora, and so forth.
It is already known that Korean historical observations reflect real phenomena (Park & La, 1994;
Yang et al., 1998, 2005b; Lee at al., 2009). Yang at al.(1998) analyze sunspot and aurora records in
Goryeosa and found 11.3-yr short period and ~97-yr long period of solar activity using power
spectrum and monte-carlo simulation analysis. The 11.3-yr short period is well known solar
activity in modern astronomy and the long-term period is also been mentioning in solar physics.
It means that sunspot and aurora records in Goryeosa are based on the real observation androyal astronomer recorded astronomical phenomena faithfully in Goryeo dynasty (Yang et al. 1998;
Park 2008). Some astronomical phenomena can be seen periodic such as motions of planet,meteor, etc. and they should be recorded in the history books repeatedly by their period. However,astronomical observation should be affected by environmental conditions such as climate, social
event, observational condition and so forth.
Yang et al. (2005a) analyze Korean historical meteor and shower records for over two thousand
years and found that periodic meteor showers such as Perseids, Orionids, north-Taurids andLeonids and examined the variation of meteor showers during 2,000 years. And they also analyze
Chinese and Japanese meteor and shower records for the same period as Korea and compare theresults with Korean one (Beijing Obs. 1988; Kanda 1935; Ohsaki 1994). Most of records in Korea
are accord with other countries but partly there are discrepancies in the distribution of meteor

2

An official history book which contains the history of Silla (新羅, 57BC – AD935), Baekje (百濟, 18BC –AD663), and Goguryeo (高句麗, 37BC – AD668).
3

An official history book of Goryeo dynasty (高麗, AD918 – 1392).

4

An official chronicles of Joseon dynasty (朝鮮, AD 1392 – 1910)

and shower records. It shows that historical records are incomplete and discontinuous although
they reflect real observational phenomena.
In order to know which environmental conditions affect astronomical records, we examine thecorrelation between some plausible political events which can influence observation anddistribution of astronomical records. In this study, we use meteor and shower records which canstand for total distribution of astronomical records in order to understand the correlation between
astronomical records and political events. We also examine Chinese and Japanese historical
records and compare them with their political events, respectively.

II.

Distributions of historical observations and political eventsThe largest astronomical record is motion of planets in Korean chronicles. Most planetary records
describe normal phenomena of planet except only a few records such as occultation of planet,seen at daylight, and so forth. The second largest observational record is meteor and shower
phenomena. Meteor is one of the frequently phenomena in the night sky and we can see meteors
all year around. Meteor can be classified with sporadic meteor and shower according to number
density seen on the ground. Meteor showers are caused by periodic comet and it appears
repeatedly at a given sidereal date annually. Thus meteor and shower are good candidates to
examine the distribution of astronomical observation. Meanwhile, it is known that historicalmeteor and shower records show periodic showers correspond to Periods, mixture of Leonids,
north-Taurids, and Orionids during past one thousand years in Korean, Chinese and Japanesechronicles (Yang et al. 2005a). Although the historical records in the three countries show same
periodic showers, observational distributions of meteor and showers are quite different among thethree countries. Therefore, in this study, we examine correlation between distribution ofastronomical observation and political events using the historical meteor and shower records.
Since many astronomical in the Three Kingdoms period of Korea does not have date and monthinformation, we limit the period from A.D. 1200 to A.D. 1700 in this study. We compare thedistribution of meteor and shower with motion of planet for A.D. 1200-1700 years. Figure 1 shows
the number distribution of planet (dash-line) and meteor (bar-histogram) and they have similartendency in number distribution.

Figure 1 Number distribution of motion of planets (dotted line) and meteor and shower
records (histogram) in Korean chronicles.
In order to compare astronomical records with political events, we select some main events whichmight influence on royal observatory. We investigate the year of new King’s accession to thethrone and political events such as foreign invasion, domestic turmoil, and so forth (Ha 1998). We
also classify political events with three grades according to their influence with the observation.
Grade of each historical event is based on the influence of astronomical observations. Table 1
shows list of major political events of Korea.
Table 1. Historical major events of Korea from A.D.1200 to 1700. (Ha 1998)
YearEvents

1231-1232

蒙古 1,2次 高麗 侵入, 高麗 首都(江華) 遷都

Mongol invasion, transfer the capital

1253-1255

蒙古 5,6,7次 高麗 侵入

Mongol invasion1259

江華 內外城 破壞, 宮 建築 (開城 遷都)

Returning to the capital1270

對 蒙古 抗爭 始作

Struggle against the Mongol

1359, 1361

紅巾賊 1,2次 高麗 侵入

Thief’s attack from China

1364

高麗 王族(德興君) 元 軍隊 聯合 高麗 反亂Revolt of royal family

1367-1374, 1379

倭賊 朝鮮 侵略Japanese invasion

1388-1392

高麗滅亡 朝鮮建國

Dynasty changed, Joseon dynasty birth1394-1453

漢陽 遷都, 1,2次 王子 亂, 癸酉靖難

Several throne competitions

1498, 1504

戊午士禍, 甲子士禍

Political troubles

1506

中宗反正, 燕山君 死亡

revolt1510

三浦倭亂

Japanese revolt

1519, 1545

己卯士禍, 乙巳士禍Political troubles

1555

乙卯倭變

Japanese revolt

1592-1597

壬辰倭亂Japanese invasion of Korea

1623-1624

仁祖反正, 李适 亂

Political troubles

1627

丁卯胡亂

Chinese invasion, transfer the capital

1636-1637

丙子胡亂

Chinese invasion, transfer the capital

We examine the cross-correlation between distribution of astronomical records and politicalevents during 500 years from 1200 to 1700 of Korea. We calculate the cross-correlation coefficient
between distribution of astronomical records and political events and cannot find any
correlation(r=-0.034) between them. We also calculate the cross-correlation coefficient using
considering weighted value for the political events but we cannot find direct correlation between
them. Moreover, we calculate the cross-correlation coefficient between distribution of astronomicalrecords and new King’s accession and also cannot find any correlation(r=-0.062) between them.
Figure 2 shows the distribution of meteor records and political events. Inverse red-filled triangles
indicate the year of new King’s accession and historical events are showing as open quadrangle,
circle and triangle according to their weight value. During the 500 years there are four notable
periods which have intensive and serious political events in Korean history. The red open circles
indicate the four periods. The first period around year of 1364-1394 has many political events
including change of dynasty while there are few meteor records. The second period of 1504-1510
and the third of 1592-1597 have relatively small observations. However, the last period of 16231637 has a lot of observations. The year of 1670-1590 (around the arrow point) shows that former
period of the Japanese invasion of Korea (1592-1597) has fewer observations rather than during
the invasion. It means that political events have no direct effect on the astronomical observationin Korean history.

Figure 2. Distribution of Korean historical observation and political events.
We also examine the cross-correlation between distribution of astronomical records and politicalevents for the same period in China and Japan (Sim 2002; Park 2011). We calculate the crosscorrelation coefficient between astronomical distribution and political events and find that r=0 for
Chinese records and r=0.083 for Japanese one. In the case of cross correlation between
observational distribution and new King’s accession, we cannot find any correlation in China andJapan. As a result, we cannot find any correlation between astronomical observation and politicalevents both in Chinese and Japanese records. Table 2 shows list of major political events in Japanand figure 3 shows the distribution of Japanese historical observation and political events.
Table 2. Historical major events of Japan from A.D.1200 to 1700. (Park 2011)
YearEvents

1221

承久の 亂

Jobu’s revolt

1333

鎌倉 幕府 亡End of Kamakura

1428

農民暴動

Jacquerie

1467-1477

應仁の 亂Onin’s revolt

1485

山城の 蹶起Yamasiro’s rise up

1488

加賀 蹶起

Gaga’s rise up

1560

桶狭間 戰鬪

Battle of Okehasima

1582

本能寺の 政變

Honnosa’s revolution

1583

賤ヶ岳の戦い, 大阪城 築城

Battle of Sizkatake

1592-1597

文祿慶長 役 (朝日戰爭)Japanese invasion of Korea

1600

關ケ原 戰鬪

Battle of Sekigahara

1637

島原の 亂

Simabara’s revolt

In figure 3, we can find four periods in which are concentrated observations. They are located in
the years of 1450-1480, 1490-1525, 1600-1630, and 1660-1680 and indicated by orange boxes. In
the Japanese history of the 500 years, the three major political events were End of Kamakura(1333), Onin’s revolt (1467-1477) and Japanese invasion of Korea (1592-1597). The period of endof Kamakura has few astronomical observation while observations are concentrated in the periodof Onin’s revolt. Hence, we know that there is no direct correlation between astronomical
observation and political events in Japan.

Figure 3. Distribution of Japanese historical observation and political events.

III.

Summary and discussions

Astronomical observations in history books are discontinuous and incomplete in Korea, China,and Japan. However, when we analyze historical records using statistical methods for periodic
phenomena, we need to calibrate weight value for each record. Hence, many people want toknow what kind of elements influence the observational condition in the history. In general, wethink that political events might be most plausible elements for astronomical observations
because observations were carried out by royal astronomers in the past. Thus we examine
correlation between the observational distribution and political events.
Yang et al. (2005a) studied historical meteor and shower records in Korean, Chinese and Japanesechronicles and found that historical records in each chronicles reflect the real observations. They
found that common peaks of Pereids and mixture of Orionids, Leonids and north-Taurids last 1000years in the three countries’ chronicles. However, observational distribution of the each country is
not the same for a given period. Thus we examine the correlation between the number ofastronomical records and political events using the meteor records.
We survey historical events which can influence astronomical observations from A.D.1200 to 1700
from Korean, Chinese and Japanese history. We examine the correlation between political eventsand meteor records and find that there are no direct correlation between them. We also examine
correlation between new King’s accession and meteor records, and cannot find any correlation. Asa result, we know that historical observations in Korean, Chinese and Japanese chronicles were notaffected directly by political events or new King’s accession. Therefore, when we analyze historicalobservations we have to consider weight value of records based on the distribution ofastronomical records.

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