THE FACE OF THE SKY FOR JUNE. 



Bv W. SHACKLETON, A.R.C.S., F.R.A.S. 



The Sun. — On the 1st the Sun rises at 3.51 and sets at 8.4 ; 

 on the 30th he rises at 3.4S and sets at 8.18. Summer com- 

 mences on the 22nd. when the Sun enters the sign of Cancer 

 at 1.35 p.m.; this is the longest day, the Sun being 16" 34™ 

 above the horizon. The equation of time is negligible on the 

 15th; hence this is a convenient day for adjusting sundials, as 

 only the correction for longitude is needed. Sunspots and 

 prominences are not very numerous; at the time of writing no 

 spots are visible. The positions of the Sun's axis, equator, and 

 heliographic longitude of the centre of the solar disc are 

 shown in the following table. An example of a disc suitable 

 for solar projection was shown on page 200 of the May issue. 



Venus : 



The Moon :- 



OcciLT.\TlONS. — The only naked eye star occulted before 

 midnight is the fifth magnitude star 22 Scorpii ; disappearance 

 takes place on the 10th at 9. 38 p.m. at an angle of 90 from 

 the N. point of the Moon, and reappearance at 10.55 p.m. at 

 an angle of 312". 



THE PLANETS. 



Mercury 



Mercury is a morning star in Taurus during the early part 

 of the month. On the 1st the planet rises in the E.N.E. at 

 3.10 a.m. ; on this date Mercury is at greatest westerly 

 elongation of 24° 30', from the Sun, but the elongation is ail 

 unfavourable one on account of the planet only rising 40 

 minutes in advance of the Sun. 



Venus is a brilliant object in the evening sky looking W'.X.W. 

 immediately after Sunset. 



The planet is extremely well placed for observation, 

 appearing high above the horizon at Sunset and not setting till 

 11.20 p.m. on the 1st and 10.37 p.m. on the 30th. Moreover, 

 the planet can readily be seen long before it is dark and even 

 in broad daylight a small pair of opera glasses is sufficient 

 optical aid to render it visible if directed to the correct 

 position in the sky. The best time for observing is whilst the 

 background of the sky is still light, for the brightness of the 

 planet is so intense that it requires an uncommonly good 

 telescope to observe when dark, partly because the planet is 

 then lower in the sky and partly on account of the luminosity 

 of the planet being strong enough to reveal any lack of 

 achromatism in the telescope ; thus in poor instruments a blue 

 halo frequently appears to surround the image. With magni- 

 fying powers of 150 to 250, dark shadings may be seen on 

 the planet's disc towards the terminator, the limb appearing 

 intensely brilliant. As seen in the telescope the planet appears 

 slightly gibbous 0'6 of the disc being illuminated, whilst the 

 diameter of the disc is about 20". The Moon appears near 

 the planet on the evening of the 29th. 



M.\RS : — 



Mars is a morning star in Pisces, rising nearly due E. early 

 in the month, and later a little N, of E, On June 1st, the 

 planet rises about 1.30 a.m., and on July 1st. about ten minutes 



I'u;i'Ki'; I. 

 Ccmjunclion of Mar.s and the Moon, June 21, 



after midnight. The planet is increasing in brightness the 

 apparent diameter being now nearly 8". On the morning of 



223 



