Joint use of eclipse records in China, Japan and Korea for the study of the earth's paleorotation

Abstract

It has become a new field to use the ancient records of astronomical phenomena for studying the secular change of the earth's rotation. China is very rich in ancient astronomical observations, to which much attention has been given recently. But the continuum of the observational series is affected critically by gaps with lengths of over half a century (TABLE 1). TABLE 1Gaps in the Time Records of Eclipses in Ancient China and Their Remedy with Ones from Japan/KoreaNo.GapDuration (in yrs)Number of J-K recordsMean frequency/10 yr.1BC145--1341112BC134--89453BC89--34554BC28--AD61885AD61--175114(5)0.56AD223--31188(2)0.27AD311--429118(2)0.28AD546--680134(3)0.29AD794--84046(5)1.110AD840--94010090.911AD959--10408191.112AD1302--1450148332.213AD1450--1572122433.514AD15781687829211.2Note: The numbers in brackets refer to the available records of the central eclipse in Japan and Korea.China, Japan and Korea are close neighbours, either adjacent to each other, or separated by a sea, and have a long history of contact and exchange in culture and science. Their ancient astronomies are similar in many aspects, and their astronomical records may be regarded as a unit. Japan and Korea have also accumulated a wealth of ancient records in astronomy, including 232 time observations from AD 840 to 1639 and 149 records of central eclipses from AD 61 to 862 (TABLE 2). However, they have not been utilized in this field. The author has especially analyzed the records of the central eclipse and eclipse time of these three countries, compared their respective merits and shortcomings, and concluded that their joint use may compose a valuable record series for the study of the earth's rotation. This work could change the situation of neglect of the ancient records of east Asia in this field. From TABLE 3 it may be seen that the united series of records are more excellent than any others. TABLE 2Comparision Between the Records of Central Eclipses in Ancient China, Japan and Korea (by the end of AD 862)ContentChinaJapanKoreaMost ancient recordBC 776 Sept. 6 (Total)AD 628 Apr. 10 (Total)BC 54 May 9 (Total)Number of solar eclipses41513467Number of central eclipses36311138Number of the available eclipse973510The ancient records of astronomical phenomena may also be used to study the evolution of the Earth-Moon system and to test the theoritical predictions of general relativity. The author has completed the analyses of the records of eclipse time, equinox time and the central eclipse, and points out that China, Japan and Korea have the potential for studying this subject. Our hope is laid on the new development of archaeology of remote ages and inscriptions on hones of the Shang Dynasty, and on interdisciplinary cooperation. TABLE 3Time Records of the Eclipse Left over by the Ancient Civilizations of the WorldRegionTime-intervalDurationNumber of recordsMean fr. per 10 yrsBabylonia & AssyriaBC 721--382349110.3Greek(Mediterranean)BC 201--AD346560100.2East AsiaBC 145--AD163018004202.1IslamAD 829--1004175331.9European?Note: The eclipse records in the inscriptions on bones of China are not included in this census.