ATA Table 640. 



MISCELLANEOUS ASTRONOMICAL DATA- 



Tropical (ordinary) year = {365.24219879 — 0.0000000614 {t — i9oo)}days 



Sidereal year = {365.25636042+0.0000000011 (t — 1900)} days 



Anomalistic year = {365.25964134 + 0.0000000304 (t — 1900)} days 



Eclipse year ={346.620000 +0.00000036 (i — i9oo)}days 



Synodical (ordinary) month = {29.530588102 —0.00000000294 (t — 1900) {days 

 Sidereal month = {27.321660890 — 0.00000000252 (t — 1900)) days 



Sidereal day (ordinary, two successive transits 

 of vernal equinox, might be called equinoctial 

 day) = 86164.09054 mean solar seconds 



= 23 h. 56 m. 4.09054 mean solar time 

 Sidereal day (two successive transits of same 

 fixed star) = 86164.09966 mean solar seconds 



1920, Julian Period = 6633 



January i, 1920, Julian-day mmaber = 2422325 



Solar parallax = 8. 7958" * o. 002" (Weinberg) 



8.807 =fc 0.0027 (Hincks, Eros) 



8. 799 (Sampson, Jupiter satellites; Harvard observations) 



8.80 Paris conference 

 Lunar parallax = 3422.63" = 57' 2.63" (Newcomb) 



Mean distance earth to sim = 149500000 kilometers = 92900000 miles 



Mean distance earth to moon = 60. 2678 terrestrial radii 



= 38441 1 kilometers = 238862 miles 



Light traverses mean radius of earth's orbit in 498. 580 seconds 



Velocity of light (mean value) in vacuo, 299860 kilometers/sec. (Michelson-Newcomb) 



= 186324 statute miles/sec. 



Constant of aberration = 20.4874" ± 0.005" 



20.47 Paris conference (work of DooUttle and others 



indicates value not less than 20.51) 



Light year = 9. 5 x lo^^ kilometers = 5.9 X 10^^ miles 



Parsec, distance star whose parallax is i sec. = 31 x 10^^ km = 19.2 X lo^^ m 



General precession = 50. 2564" + 0.000222 (t — 1900)" (Newcomb) 



Obliquity of ecUptic = 23° 27' 8. 26" — 0.4684 (t — 1900)" (Newcomb) 



Constant of nutation = 9. 21" (Paris conference) 



Gravitation constant = 666 . 07 x 10""^° cm^/g sec^ ±0.16 X lo"^" 



Eccentricity earth's orbit = e = 0.01675104 — 0.0000004180 (t — 1900) — 



0.0000000000126 {i — 1900)2 



Eccentricity moon's orbit = 62 = 0.05490056 (Brown) 



Inclination moon's orbit = / = 5° 8' 43 . 5 " (Brown) 



Delaunay's y = sin |/ = 0.04488716 (Brown) 



Lunar inequaUty of earth = L = 6 . 454" 



Parallactic inequality moon = Q - 124. 785" (Brown) 



Mean sidereal motion of 1 o ^ o o '/ , /^ \t/ 



, ,. ^^,j > = — 19 21 19.3838 + 0.001294 {t ~ 1900) 

 moon s node m 365.25 days] ^ yooi v-r^ y/ 



Pole of Milky Way = R. A., 12 h. 48 m.; Dec, +27° 



Smithsonian Tablss. 



