266 



THE GUIDE TO NATURE 



Figure 3 — View showing the general form of ap- 

 pearance of the Zodiacal Light. 



its diminishing distance from us, and 

 as it changed first to a half circle and 

 afterwards to a narrow crescent, pro- 

 vides one of the most interesting of all 

 observations for the possessor of a 

 small telescope. 



On February 10, at 7 A. M., the moon 

 will pass between the earth and Venus, 

 hiding the planet from view. This most 

 interesting sight will be visible to 

 many observers in the southern hemis- 

 phere, but unfortunately the earth is so 

 large that those who are above the 

 equator will look over the upper edge 

 of the moon and hence see the planet 



every month of this year we will not 

 be able to witness it for the first time 

 until September 20. 



Mercury enters the evening sky on 

 February 12, and though it does not 

 reach its greatest elongation until next 

 month, it may nevertheless during the 

 last evenings of February be clearly 

 seen. It will be found low in the twi- 

 light glow, a little south of the west 

 point, for about one and three fourths 

 hours after sunset. 



Saturn is still in excellent position 

 for obssrvation, as it shines out just 

 below the Pleiades in the southwest. 

 The rings now show nearly their maxi- 

 mum width and the whole wonderful 

 system forms a most beautiful object 

 for study with a small telescope. 



The other bright planets are now all 

 morning stars. 



THF, ZODIACAL LIGHT. 



During the moonless evenings which 

 occur at the end of this month and the 

 beginning of March, the observer 

 should not fail to look for this faint but 

 most interesting object. He should go 

 out of doors on any clear evening, away 

 from all sources of artificial light, as 

 soon after sunset as the sky has become 

 dark, and face directly toward the 

 west. He will then readily detect the 

 light, which will appear as a great, faint 

 pyramid, whose widest part rests upon 

 the horizon and whose apex may ex- 

 tend nearly to the Pleiades, or even 



C TgATBEia 



•POTSTIOM 





OF u&^ r 



Figure 2 — Cross seition of the Zodiacal Light showing the supposed portion of this great circular cloud. 



apparently above our satellite. Even 

 were this not the case, the occultation 

 occurs at such an hour that both ob- 

 jects will long since have set to all ob- 

 servers in the United States. It may 

 be added that the moon will pass over 

 the Pleiades on February 12 at 10 A. 

 M., and on March 13 at 4 P. M., both 

 of which will be invisible to us for simi- 

 lar reasons. Though the occultation of 

 this little group of stars will occur 



farther. The center of the widest part 

 of the base is at the point at which the 

 sun set, the light is here brightest, and 

 it grows rapidly fainter as its borders 

 are approached. 



There can be but little doubt that 

 this strange light is caused by a great, 

 fiattened swarm of little particles which 

 surrounds the sun and extends some- 

 what beyond the orbit of the earth, the 

 form of its cross section being very ap- 



