Earth s rotation derived using contemporary solar eclipses

Transcription

1 Earth s rotation derived using contemporary solar eclipses ( ) Mitsuru Sôma and Kiyotaka Tanikawa National Astronomical Observatory of Japan Mitaka, Tokyo , Japan Mitsuru.Soma@nao.ac.jp, tanikawa.ky@nao.ac.jp Abstract. First we show that the lunar tidal acceleration has been almost constant since BC 200 using the solar eclipse records of the years of around BC 200 and AD 600. Next we investigate the variation of the Earth s rotation speed between AD 1 and AD 1200, and show that there were abrupt changes in the Earth s rotation speed in the years of around AD 500 and AD (VLBI) UTC (Table 1) Table 1: ( UTC 1 ). 0 UTC.

2 Table 2: Author ṅ in /cy 2 Method Spencer Jones (1939) Lunar motion relative to planets Van Flandern (1970) 56 ± 16 Brown s theory Morrison (1973) 42 ± 6 Brown s theory Van Flandern (1975) 65 ± 18 Numerical integration Oesterwinter & Cohen (1975) 38 Numerical integration Morrison & Ward (1975) 26 ± 2 Lunar motion plus Mercury s transit Muller (1976) 30 Eclipses Calame & Mullholland (1978) 24.6 ± 5 LLR Williams et al. (1978) 23.8 ± 4.0 LLR Ferrari et al. (1980) 23.8 LLR and lunar orbiter Dickey et al. (1982) 23.8 LLR Dickey and Williams (1982) LLR Newhall et al. (1988) LLR Dickey et al. (1994) ± 0.50 LLR Chapront & Chapront Touzé LLR (1997) Chapront et al. (1999) LLR Chapront et al. (2000) LLR Chapront et al. (2002) ± LLR Spencer Jones Clemence (1948) VLBI 17 T T = TT UT TT TAI TT = TAI + 32 ṣ 184 TT TT UT T

3 2. ELP (Chapront & Chapront-Touzé 1997) T T 2 Williams (1994) T 2 Table 2 (ṅ ) Brown (Sôma 1985) /cy 2 JPL DE406 DE The Astronomical Almanac DE405 (Standish 1998) Chapront et al. (2002) DE405 DE /cy 2 Morrison & Ward (1975) 26 /cy T T T Fig /cy

4 Table 3: T Date Place Description T /sec AD 22 Nov Dec Jan Jul Aug 28 ; Dec 12 ( ) Aug Jan 14 Athens day turned into night Apr 18 ( ) Jun May Apr Sep Oct Aug Apr 25 and May 5 Bergamo Total Jul Jul 28 Nishapur Moon in the middle of Sun Aug 8 Constantinople Stars seen ( ) 912 Jun 17 Cordoba Total Jul 19 Olmos or Total Cueva del la Mora 968 Dec 22 Constantinople Total Dec 22 Farfa Total Aug 10, Jan 24 Cairo Like a crescent Moon 1746 or Jan Jun 20 Baghdad Total Feb 16 Sicily They lit lamps 1033? 2095? 1133 Aug 2 Several places Total in Europe 1140 Mar 20 Malmesbury Stars seen around Sun ( ) 1147 Oct 26 Brauweiler Circle (Annular) Apr 11 Antioch Total Apr 11 Cizre Total Sep 13 Vigeois Partial 1142 or 2337

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