522 



KNOWLEDGE & SCIENTIFIC NEWS. 



[Auc 



1906. 



The Face of the Sky for August. 



]jy W. Shackleton, F.R.A S. 



The Sun. — On the ist the Sun rises at 4.23 and sets at 

 7.4S ; on the 31st he rises at 5.1 1 and sets at 6.49. 



There is a partial eclipse of the Sun on the igth, but 

 no part is visible in this country ; it is only visible from 

 the Arctic regions and \\'est of Canada. The magnitude 

 of the eclipse is o'3i5 (Sun's diameter = i). 



Sunspots, after a period of sparseness, are again fairly 

 numerous ; at the time of writing several conspicuous 

 groups are visible on the solar disc. 



The positions of the Sun's axis, centre of the disc, and 

 heliographic longitude of the centre are given in the 

 following table : — 



Axis inclined 

 from N. point. 



Centre Heliographic 



N. of Sun's I Longitude of 



Equator. 1 Centre of Disc. 



There is a total eclipse of the Moon on the morning of 

 the 4th. It is invisible in this country, but visible over 

 part of North America and the greater part of the Pacific 

 Ocean. 



OccuLTATioNS. — The following are the particulars of 

 the occultations visible from Greenwich before mid 

 night : — 



The Planets. — Mercury (Aug. i, K.A. g^ 46™; 

 Dec. N. 9° 3'. Aug. 31, R.A. 911 26™ ; Dec. N. 15° 12') 

 is in inferior conjunction with the Sun on the 12th, and 

 hence is invisible during the former part of the month ; 

 towards the end of the month the planet is a morning 

 star in Leo, and attains a greatest westerly elongation of 

 iS"^ 11' on the 29th. This is a favourable elongation, the 

 planet rising at 3.26 a.m. 



Venus (Aug. i, R.A. ii'' 21'"; Dec. N. 5^ 5'; 

 Aug. 31, R.A. i3i> 2im; Dec. S. 9" 59') is an evening 

 star in Virgo, and may be observed in the evening sky 

 looking W. immediately after sunset. As seen in the 

 telescope the planet appears gibbous, 0-65 of the disc 

 being illuminated. 



On the evening of the 7th the planet will appear in 

 conjunction with the star /j Virginis, as shown in the 



diagram, the separation being only 15' at i p.m. On this 

 date the planet sets at 9 p.m. 



Mars (Aug. i, R.A. 8" 23"" ; Dec. N. 20° 31' ; Aug. 31, 

 R.A. g*" 40 ™; Dec. N. 15° 10') is a morning star, rising 

 about 3.45 a.m. throughout the month. 



Jupiter^.Vug. i, R.A. 6'' i"" ; Dec. N. 23=8'; Aug. 31, 

 R.A. 6h 25™ ; Dec. N. 23° 2') rises about i a.m. on the 

 1st of the month, and about 11.30 p.m. on the 31st. The 

 planet is situated near the star i Geminorum. 



Saturn (i\ug. i, R..-\. 2^^' 4'"; Dec. S. S'' 9'; Aug. 31, 

 R.A. 22i> 57r" ; Dec. S. 9° o') is an evening star describing 

 a retrograde path in Aquarius. Near the middle of the 

 month the planet rises about 8 p.m., and is on the meri- 

 dian at 1.30 a. in. W'e are looking on the northern sur- 

 face of the ring, the outer major and minor a.xes of which 

 are 44" and 3'' respectively, whilst the apparent semi- 

 diameter of the ball is 8"-8. 



Uranus (.A.ug. 15, R..'\. 18'' 21'" ; Dec. S. 23° 41'), 

 though somewhat low down in the sky, is well placed for 

 observation during the early evening, the planet being 

 due south on the 13th at 8.48 p.m. He is situated 

 a little to the S.E. of the star ^i Sagittarii. Uranus is 

 just perceptible to the naked eye, but can easily be seen 

 with a pair of opera glasses. The diameter of the disc 

 is nearly 4", and the colour is greenish. As seen in large 

 telescopes the planet appears more luminous at the centre 

 of the disc than at the limb — somewhat similar to Jupiter 

 and Saturn. 



Neptune (Aug. 15, R..\. 6^ 50"' ; Dec. N. 22" 4') does 

 not rise until after midnight. He is situated about i^ 

 north of the star j- Geminorum. 



Meteors : — 



Date. 



Radiant. 



Aug 10-12 45^ + 57° 



1 

 Aug. 21-25 291^ -I- 60° 



Great Pcrstid shower; radiant 

 moving E.N.E. about i^ 

 per day. 



Draconids ; bright slow 

 meteors. 



Minima of Algol occur on the 19th, at 0.16 a.m., and 

 on the 2ist, at 9.5 p.m. 



Mira (0 Ceti) is due at minimum on the 15th, but fre- 

 quently the phases are retarded ; the star varies from 

 magnitude 3-3 to 8-5. 

 Telescopic Objects: — 



Double stars : Polaris, mags. 2'i, 9'5 ; separation i8"'6. 

 The visibility of the fainter star is frequently used as a 

 test for a good 2-inch object glass. 



f Sagitta;, XlX.h 45", N 18° 53', mags. 5, 10; sepa- 

 ration, 8"-6. 



o> a- Capricorni XX^ 12"% S. 12° 15', mags, a' 4-5, 

 a- 3-8 ; naked eye double, separation 373", very easy with 

 opera glasses. 



