494 



KNOWLEDGE & SCIENTIFIC NEWS. 



[July, 1906. 



TKe Face of the Sky 

 for July . 



By Prof. A. Fowler, F.R.A.S., and 

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



The Sun. — On the ist the Sun rises at 3.48 and sets at 

 8.18; on the 31st he rises at 4.23 and sets at 7.49. On 

 the 3rd, at 7 a.m. the earth is at its greatest distance 

 from the sun, the solar parallax then reaching its minimum 

 value of S"'66. 



Notwithstanding the declining solar activity, sun-spots 

 and solar prominencesare still fairly numerous. Eruptive, 

 or metallic, prominences, however, have lately been of 

 somewhat rare occurrence. 



There is a partial eclipse of the Sun on the 21st, but 

 no part of the phenomena will be visible in this country, 

 the favoured regions being the South Atlantic, the Falk- 

 land Islands, and S. Patagonia. At the maximum phase 

 about one-third of the Sun's disc will be obscured. 



The positions of the Sun's axis and equator, and the 

 heliographic longitude of the centre of the disc, are 

 shown in the following table : — 



Heliographic 

 Longitude of 

 Centre of Disc. 



59° 54' 



353° 44' 



287= 33' 



221° 24' 



155° 12' 



89° 4' 



22^ >;6' 



June 30 



July 5 



The Moon :^ 



OccuLTATiONS. — The following occultation is visible 

 at Greenwich before midnight : — 



Mean Angle from I ^^^^ Angle frt 

 Time N. xim-. ^'■ 



pomt. ' - pomt. 



July 



S.52 



The Planets. — Mercury (July i, R.A. 8" 14'"; 

 Dec. N. 21° 27'. July 31, R.A. gh 47m; Dec. N. 9° 9') 

 is an evening star throughout the month, reaching its 

 greatest easterly elongation of 26^ 39' on the i^th. 



On the ist he sets at 9.43, on the 13th at 9.22, and on 

 the 25th at 8.35 p.m., but in consequence of the long 

 twilight is not favourably placed for naked eye observa- 

 tion. The planet is stationary on the 26th. 



Venus (July i, R.A. 9'' 3"; Dec. N. 18° 41'; 

 July 31, R.A. iii^ 17™; Dec. N. 5° 35') is an evening 

 star, and is a conspicuous object in the western sky after 

 sunset. On the ist she sets at 10.14 P-m., and on the 

 31st at 9.16 p.m. The apparent diameter increases from 

 i3"-2 to 1 5"-8 during the month. Telescopic examination 

 will show that the planet is gibbous, about three-quarters 

 of the disc being illuminated. The planet is in conjunc- 

 tion with the crescent moon on the 24th at 7 p.m., the 

 planet then being i 23' to the south of the Moon. 



Mars is not observable this month, being in conjunc- 

 tion with the Sun on the 15th. 



Jupiter (July i, R.A. 5'" 32'" ; Dec. N. 22' 56' ; July 31, 

 R.A. 6h o"' ; Dec. N. 23° 8') is a morning star throughout 

 the month, rising at 2.46 a.m. on the ist, and at 1.14 a.m. 

 on the 31st. He will be found in the eastern part of 

 Taurus. 



Saturn (July i, R.A. 23'' 8™; Dec. S. 7° 39'; July 31, 

 R.A. 23'! 4™ ; Dec. S. 8° 8') is coming into a more favour- 

 able position for observation, rising at 11. 7 p.m. on the 

 1st and at 9.31 p.m. on the 31st. He is describing a 

 retrograde path in Aquarius. The apparent axes of the 

 outer ring at the middle of the month are respectively 

 43" and 2"-6, while the polar diameter of the ball is 17". 

 The northern surface of the ring is presented to the 

 earth. 



Uranus (July 16, R.A. 18'' 25'" ; Dec. S. 23° 28') is 

 rather low in our latitudes, but is otherwise well placed 

 for observation. The planet is in Sagittarius and rises 

 at about 7 p.m. near the middle of the month, and then 

 crosses the meridian at 10.50 p.m. ; it will be then about 

 three quarters of a degree east, and nearly two degrees 

 north of \ Sagittarii (mag. 2-9). Its remarkable spec- 

 trum of broad dark bands is well worth the attention of 

 observers, even though possessing only small instru- 

 ments. 



Neptune is not observable this month, being in con- 

 junction with the Sun on the 2nd. 



Meteor Shower. — The most notable shower in July 

 is that of the Aquarids, which occurs on the 28th. 

 The radiant is situated in R.A. 22 h. 6 m., Dec. S. 11°, 

 and the meteors are slow with long trails. 



Telescopic Objects (double stars, cScc.) : — 5 Serpentis, 

 XV.h 13™, N. 2° 13', mags. 5-1, 10; separation 10". 



^ Serpentis, XW^" 41™, N 15° 44', mags, 3-8, 10; sepa- 

 ration, 31". 



" Serpentis XVIII.'' 51'", N. 4° 4', mags. 4-0, 4-2 ; 

 separation, 2i"-6. Both are yellow, the primary being 

 paler than the smaller star. 



s' Cephei XXII.^ i", N. 64° 8', mags. 4.'7, 7 ; separa- 

 tion, 6". 



S Cephei XXII*" 26"", N 57° 56', mag. 4-2, 7 ; separa- 

 tion 40". A pretty pair for small telescopes, stars re- 

 spectively yellow and blue. It is also a typical short 

 period variable star, not of the Algol type, the period 

 being ^^ g^, with a sharp rise from minimum to maxi- 

 mum in i'^ 9*'. There will be minimum on the 2nd at 

 3 a.m., from which succeeding minima and maxima may 

 be calculated by the intervals given. 



Cluster in Libra, M 5. A compact cluster situated 

 about one-third of a degree north of the double star 

 5 Serpentis ; it appears like a large nebulous star when 

 viewed with a pair of opera glasses. c ■ ?. 



Cluster in Serpens, >s.G.C. 6633; about one-third Jof 

 the way from S Serpentis to a Ophiuchi. The cluster is 

 visible to the naked eye. 



