THE FACE OF THE SKY 1^X)1^ JFLV 



By A. C. D. CKOMMl^LIX. \\.\.. D.Sc. I-\K..\.S. 



h. in. „ 



22 36 6 S. 12-3 

 2 22-0 N'.i6-i 

 7 iVg N.2e-8 

 .2 .9-4 S. i-o 

 16 28-4 S. 75*9 

 20 52 5 S. 223 



Mercury. 

 R.A. Dec. 



845-6 

 9 "S"! 

 9 40"' 



6 50-9 N.23-5 



7 17-6 23-0 



Table 22. 



P is the position angle of the North end of the body's axis measured eastward from the North Point of the disc. B. L 



are the helio-(planeto-lgraphical latitude and longitude of the centre of the disc. In the case of Jupiter Li refers to the 



equatorial /cone, L2 to the temperate zones. Ti Ti are the times of passage of the two zero meridians across the centre of the 



disc; to find intermediate passages apply multiples of Q*" 504"", 9*' DSi™ respectively. 



The letters m, e stand for morning, evening. The day is taken as beginning at midnight. 



Thk Sl'N is moving South again. It is at its greatest dis- 

 tance from the Earth July 4"* 11'' t', its semi-diameter is then 

 15 45"-35. and 15' 47"-0 on Julv 31st. Sunrise varies from 

 3" 49"' to 4" 24'" ; sunset from S" 18"" to 7" 49"'. 



Mercury is an evening star; it is in elongation, 27° from 

 Sun July 25th. Semi-diameter increases during month from 

 2J" to 41"; fraction of disc illuminated diminishes from 0-S to 

 0-4. 



Venus is in superior conjunction with Sun July 5th, and its 

 disc is therefore fully illuminated, semi-diameter 4"- 9. 



The Moon.— Last Quarter Julv 7" 4" 47'"c ; New 

 14^ 1" ii'^e; First Quarter 21'' 5" 18"" m; Full 29" 4'' 

 2S"'/H. Apogee 2"' l^iii. semi-diameter 14' 44-2"; Perigee 

 14'' 12" e, semi-diametar 16' 44-3"; Apogee 29"* S"*!;*, semi- 



diameter 14' 43-5". Minuiiiim Librations. July 9 , 7° E., 

 W 7" S., 21" 8" W.. 27'' 7' N. '1 he letters indicate the 

 region of the Moon's limb brought into view by libration. 

 E. W. are with reference to our sky, not as they would appear 

 to an observer on the Moon. 



Mars is too near the Sun for useful observation ; it is still 

 an evening star. 



Jupiter is an evening star. Its equatorial semi-diameter 

 varies from 22" to 20i". the polar is smaller by lA". The 

 configurations of the satellites at lO'' c are for an inverting 

 telescope (see Table 24). 



Satellite phenomena visible at Greenwich, 2'' 8'' 42'" bb'c 

 III. Ec. K., 11" 18'"c II. Tr. I.; 3" O" 42"'m II. Sh. I.; 

 4" 0" 27"'(H I. Tr. I., 1" \2"'m I. Sh. I., 9" 44"'.; 1. ()<-. D.. 



Table Zi. Occultations of stars by the Moon visible at Greenwich. 

 The asterisk indicates the day following that printed in the date column. 

 New to Full disappearances take place at the Moon's Dark Limb, from Full to New reappearances. 



223 



