TABLE 88. 109 



MISCELLANEOUS ASTRONOMICAL DATA. 



Length of sidereal 5^1=365.2563578 mean solar days ; 



=365 days 6 hours 9 minutes 9.314 seconds. 



Length of tropical year=365.242i9987o 0.0000062124 ^-^mean solar days; 



=365 days 5 hours 48 minutes [46-069 0.53675 ^ j seconds. 



Length of sidereal month 



=27.321661162 0.00000026240 days; 



=27 days 7 hours 43 minutes [ n-5 2 4 0.022671 j seconds. 



Length of synodical month 



,. , t 1800 . 

 = 29. 530588435 0.00000030696 days ; 



=29 days 12 hours 44 minutes [2.841 0.026522 -A seconds. 



V ' } 



Length of sidereal day =86164.09965 mean solar seconds. 



N. B. The factor containing /in the above equations (the year at which the values of the 

 quantities are required) may in all ordinary cases be neglected. 



Mean distance from earth to sun = 92900000 miles = 149500000 kilometers. 

 Eccentricity of the earth's orbit = e = 



// 1900X2 



V I0 )' 

 Solar parallax = 8.7997"^- 0.003 (Weinberg, A. N. 165, 1904) ; 



8.807 -J- 0.0027 (Hinks, Eros, 7); 



8.799 (Samson, Jupiter satellites ; Harvard observations). 

 Lunar parallax = 3422.68". 



Mean distance from earth to moon = 60.2669 terrestrial radii ; 



= 238854 miles ; 

 = 384393 kilometers. 



Lunar inequality of the earth = L = 6.454". 



Parallactic inequality of the moon = Q = 1 24.80". /_i8oo X 



Mean motion of moon's node in 365.25 days = /* = 19 21' 19.6191" + 0.14136" f IOO/ 

 Eccentricity and inclination of the moon's orbit = e 2 = 0.05490807. 

 Delaunay's y = sin ^ 7= 0.044886793. 



7= 50 08' 43-3546". 

 Constant of nutation = 9.2'. 



Constant of aberration = 20.4962 ^- 0.006 (Weinberg, 1. c.).* 

 Time taken by light to traverse the mean radius of the earth's orbit 



= 498.82 -|- o.i seconds (Weinberg) ; 

 = 498.64 (Samson). 



Velocity of light = 186330 miles per second (Weinberg) ; 

 = 299870 ^ 0.03 kilometers per second. 

 General precession = 50.2564" + 0.000222 (t 1900). 

 Obliquity of the ecliptic = 23 27' 8.26" 0.4684 (/ 1900). 



Gravitation constant = 666.07 X IQ- 10 cm 8 /gr. sec 2 ^ 0.16 X lO" 10 . 



0.01675104 0.0000004180 (/ 1900) 0.000000126 



* Recent work of Doolittle's and others indicates a value not less than 20.51. 

 SMITHSONIAN TABLES. 



