200 



THE GUIDE TO NATURE 



at the constant interval of two days. 

 twenty hours and forty-eight minutes 

 thereafter. 



Above Perseus is the large constel- 

 lation Andromeda, with its wonderful 

 nebula at N, while beyond Andro- 

 meda, riding high in the southeast, is 

 the so-called Great Square of Pegasus. 

 An excellent test of one's keenness of 

 sight and of the excellence of his sta- 

 tion for observing is readily made by 



looked only at the brighter star 

 groups and taken no pains to secure 

 the best conditions for his observing. 

 The Planets in October. 

 By far the most striking object now 

 in the heavens is the brilliant planet 

 Jupiter, which shines out with its 

 steady, golden radiance, well up from 

 the ground in the south, a little to the 

 west of the meridian. For many years 

 past this planet has been so far south 



Figure 2. The path of the new comet during October. 



merely counting the number of stars 

 which he can detect with his naked eye 

 within the borders of this square. In 

 making this observation a perfectly 

 clear, moonless night should be se- 

 lected and the observer must be care- 

 ful to be away from all artificial light. 

 Argelander, a celebrated German as- 

 tronomer, who made a great catalogue 

 of three hundred thousand stars, stated 

 thirty as the number visible to the eye 

 under the best conditions. Another as- 

 tronomer, under a wonderfully clear 

 sky near Athens, counted no less than 

 one hundred two. If the observer de- 

 tects from twenty to thirty, however, 

 he may be satisfied that both his eye 

 and the seeing at his station are ex- 

 cellent. 



There are certain special advantages 

 to be gained by a simple study of this 

 kind, for in this way the observer not 

 only learns how to look for very faint 

 objects, and becomes accustomed to 

 doing so, but he also becomes able to 

 judge of the excellence or poorness of 

 any selected night for general obser- 

 vations. After having made this study 

 under the favorable conditions here 

 mentioned, he will doubtless be sur- 

 prised at the great multitude of other 

 faint objects which he will detect in all 

 parts of the sky and which would have 

 been whollv invisible to him had he 



of the Celestial Equator that it could 

 never mount high in our heavens, but 

 its slow, steady, upward motion is 

 now well under way. It will pursue 

 the path EVH, Figure I, reaching V 

 on February 10, 1916, and will then 

 pass through Taurus and afterward 

 reach the summer solstice some three 

 years later. It will then be seen shin- 

 ing in our evening heavens from a 

 higher position than the sun reaches, 

 even in midsummer. 



To watch the moving moons of this 

 planet and its ever changing markings 

 is always an observation of much in- 

 terest. Many eclipses and other phe- 

 nomena of the moons occur this 

 month. For example, on October 1 1 

 the third moon will emerge from be- 

 hind the planet at 7:09 P. M., this 

 moon will next enter the planet's 

 shadow and be eclipsed at 8:29 P. M. 

 The first moon will begin to transit 

 across the planet's disc at 8:32, and 

 will pass off of the disc at 10:52. Fi- 

 nally, the third moon will emerge 

 from its eclipse at midnight. 



Venus, which now shines low in the 

 southwestern sky after sunset, will 

 reach its greatest brilliance on Octo- 

 ber 23, and even at the beginning of 

 the month it is no less than eight and 

 one-half times as bright as Jupiter. 

 But, unfortunately, it is running very 



