TO KNOW THE STARRY HEAVENS 



83 



aiiioiii^' the stars, l)Ut tliis nuuion is so 

 slow that it will rc(|uirc 7000 years for 

 its ])laee to heconie chanj^'ed by an 

 amount equal to the ajjparent distance 

 across the full moon Of the two faint 

 stars, A and B, Figure 1. wdiich with 

 \'ega form an ecjual-sided triangle, the 

 former is seen to be an interesting 

 double in an opera or field glass, while 

 a larger telescope reveals it as a re- 

 markable c[uadruple system of suns. 

 The latter is an unequal pair of a 

 greenish color. Almost on a line with 

 E and D, but nearer to the latter, is 

 the remarkable Ring Nebula, which in 

 a small telescope appears as a dim. 

 misty, oval patch of light of about the 

 size of the planet Jupiter. This is one 

 of the gaseous nebulas, of whose nature 

 and development we know very little. 

 The}' may be matter in a very primi- 

 tive condition from which denser 

 clouds, and finally systems, may de- 

 velop in the course of ages, or they 

 mav. as some think, be a disintegra- 

 tion product, formed possibly at the 

 time of the tearing apart or breaking 

 up of a star. This nebula is the best 

 example of its type in the heavens ; 

 the Great Nebula of Andromeda, at N. 

 is the finest example of the second 

 large class of nebulas, which are of a 

 whitish color and of a spiral structure. 



^ :5; ;)j ;!c ^ 



The Occultation of Saturn. 



The beautiful phenomenon will oc- 

 ctu" on the early morning of Augtist 

 25, when the crescent, wajiing moon is 

 btit two days from new. As seen from 

 Washington, the bright, advancing, 

 east edge of the crescent will begin to 

 cover the disc of Saturn at about 3 A. 

 M. (Eastern Standard Time). The 

 planet will remain hidden for 1 hour i 

 minute, after which it will begin to 

 emerge from behind the dark, west 

 vdge of the ball. At this time the 

 whole ball of the moon will probably 

 be dimly visible to the naked eye. be- 

 ing faintly illuminated by the light 

 from the nearly full earth. 



The exact instants of the beginning 

 and ending of the occultation cannot be 

 given for all different observers be- 

 cause these are much influenced by the 

 observer's position upon the earth. To 

 be certain of witnessing the phenome- 

 non the reader should therefore go out 



and turn toward the eastern heavens 

 at shortly before 3 A. AI. (Eastern 

 Standard Time), noting the positions 

 of the moon and Saturn with reference 

 to each other. By considering that our 

 satellite moves eastward among the 

 stars an amount equal to its own diam- 

 eter in the course of an hour, he can 

 estimate quite closely when the occul- 

 tation will occur. It is very unfortunate 

 that in the extreme south central parts 

 of our country and also in the Far West 

 the occultation cannot be witnessed be- 

 cause the moon and Saturn will not 

 have risen ; in the Mississippi Valley 

 the end only can be observed, but in 

 the Eastern States the entire phenom- 

 enon will be visible. 



In the telescope one will see the 

 steadily advancing, bright edge of the 

 moon successively cover the satellites 

 of the planet, the w^estern part of the 

 ring, the ball, and finally the eastern 

 edge of the rings, all of which objects 

 will afterward re-appear in the inverse 

 order from behind the dark, or western, 

 limb. Altogether, an occultation of 

 Saturn is of more interest than that of. 

 any other of the planets. 



The Planets in August. 



]Mercnr\' is in the evening sky, but 

 is invisible throughout the month since 

 it does not come to its greatest eastern 

 elongation before September 9. 



Venus is very conspicuotis in the 

 east for a few hours before dawn. In 

 the course of the month it moves east- 

 ward across the constellation Gemini ; 

 during this time it wnll be seen in the 

 telescope to be rapidly losing its cres- 

 cent shape though it wmII not become 

 exactly^ half full until September 12. 



Mars will be seen low in the south- 

 west for a few^ hours after sunset. Dur- 

 ing August it will move eastward 

 through Mrgo. passing tw^o degrees 

 north of the bright star Spica on Au- 

 gust 28. At this time the two objects 

 will form an interesting stellar figure 

 in the southwestern heavens, for the 

 reddish color of Mars will contrast 

 strongly with the l)lue color of the 

 star. 



Jupiter rises almost due east at about 

 II P. ]\I. on August I, and at about 9 

 P. M. on August 31. It is in excellent 

 position for observation during the 

 earlv morning hours. 



