28o 



THE GUIDE TO NATURE 



spicuous in the southwestern heavens 

 after sunset, will pass to the west of 

 the sun and so become a morning star 

 on February 7. Toward the end of the 

 month it may be seen before sunrise, 

 creeping outward from the sun's rays, 

 but it will not attain its greatest bril- 

 liance in the morning heavens until 

 March 16. 



Mars is just beyond the eastern bor- 

 ders of our evening map, in the western 

 portion of the constellation Virgo. On 

 February 1 the planet is two degrees 

 due north of the bluish, variable star 

 Eta, or Virgo, while by February 28 it 

 will be thirteen minutes to the west of 

 this star. Mars rises almost exactly at 

 the east point of the horizon at 9 hrs. 



20 min. P. M. on February 1, but this 

 time is diminished to 7 hrs. 20 min. by 

 February 28, when the planet will be 

 seen high in the evening heavens. 



Jupiter and Saturn are both in excel 

 lent position for observation. The for- 

 mer planet is in Taurus and the latter 

 is in Cancer, in the positions indicated 

 in Fig. 1. The retrograde motion of 

 Jupiter has now ceased and during the 

 month it will move eastward an 

 amount about equal to twice the ap- 

 parent diameter of the full moon. Sat- 

 urn, however, is retrograding and will 

 continue to do so until April 9. 



Uranus enters the morning sky on 

 February 12. Neptune is in Cancer, 



21 minutes to the west and 29 minutes 

 north of Saturn on February 1 : these 

 figures diminish, however, to 18 

 minutes and 1 minute, respectively, by 

 February 28. If on the latter date the 

 observer will point his telescope on 

 Saturn, and leave it undisturbed for 17 

 minutes 52 seconds, he will then see the 

 more distant planet exactly in the cen- 

 ter of the field of view. 



In astronomies written fifty or more 

 years ago, the reader will find the spec- 

 ulation whether these clusters may not 

 be universes of stars, not so very un- 

 like our own universe, but almost in- 

 conceivably remote from us. From 

 more modern books he will learn that 

 it is far more reasonable to regard them 

 as dense clouds immersed in and a part 

 of our Milky Way universe. 



Several different lines of investiga- 

 tion are now leading us to believe that 

 the older conception was in the main 

 the truer one. It is evident that these 

 clusters are of a very different struc- 

 ture from that of our flattened, very 

 heterogeneous and extended Milky 

 Way cluster, yet a study of four of 

 the spherical clusters leads to figures 

 so great as from 15,000 to 50,000 light 

 years for their distance away from us. 

 Thus they are on the outer boundaries 

 or even far beyond the limits of our 

 visible universe. 



Of four clusters studied the nearest 

 was found to be the magnificent clus- 







Spherical Star Clusters. 



Quite recently astronomical interest 

 has largely centered in those remark- 

 able aggregations of faint suns, found 

 in many parts of the sky, which are 

 known as spherical clusters. In the 

 telescope these beautiful objects appear 

 as almost perfectly spherical balls of 

 innumerable points of light, toward the 

 center of which, however, the crowding 

 is so great that the separate stars are 

 no longer distinguishable. 



Figure 3. The great spherical cluster of stars i:i 

 k he constellation Centaurus. 



ter in the southern constellation Cen- 

 taurus. This is not surprising, since 

 this cluster appears so much larger 

 than any of the others ; its apparent 

 diameter is two-thirds that of the full 

 moon and it is easily visible to the 

 naked eye. We would naturally ex- 

 pect, therefore, that it would prove to 

 be our nearest neighbor among this 

 class of objects. 



