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THE GUIDE TO NATURE 



The Zodiacal Light 



Toward the end of this month and dur- 

 ing the first weeks of March the observer 

 should occasionally attempt to obtain a 

 view of this mast interesting object, with 

 which so comparatively few observers 

 are familiar, but which is not at all dif- 

 ficult when the atmospheric conditions 

 are favorable. For this purpose he 



Mercury, Venus and the Earth are im- 

 mersed, and that it is the reflected sun- 

 shine from this enormously extended, 

 but exceedingly tenuous, cloud which is 

 seen by us as the Zodiacal Light. 



The probable position of the boundary 

 of the Zodiacal Light when seen during 

 this month is shown by the dotted line 

 in Figure 1. 



Fig. 4. — Regions within which the solar eclipse of 

 February 13-14 is visible. 



should go out on a perfectly clear night, 

 as soon after sunset as the sky has be- 

 come dark, and face the western horizon 

 He may then see a great area of faint 

 light in the shape of a rounded pyramid, 

 the center of whose base rests upon the 

 horizon at the point in which the center 

 of the sun has set, and whose blunt apex 

 may extend upward to the Pleiades, or 

 even higher. 



The part of the light which is nearest 

 the sun is the brightest, and it fades 

 away from the axis of the pyramid so 

 that its boundaries are difficult to deter- 

 mine with exactness. Usually this light 

 is considerably fainter than the Milky 

 Wav. but it is not aways so ; and, in fact, 

 its brightness at times fluctuates in an ir- 

 regular manner; the cause of this is as 

 yet unknown, hut it is believed to be of 

 an electrical nature. 



For a long time the nature of this faint 

 light was a mystery, and it was even un- 

 certain whether it was a truly celestial 

 phenomenon at all. But as observations 

 multiplied it became evident that its 

 brightest portion always remained near- 

 est the sun and that as the latter body 

 pursued its apparent annual course 

 among the constellations it carried the 

 Zodiacal Fight always with it. It thus be- 

 came certain that this was a truly solar 

 phenomenon, and not merely an atmos- 

 pheric one. In fact, we now know that 

 the sun is surrounded by a great, flatten- 

 ed cloud of little particles, within which 



The Planets in February. 



Mercury, which entered the evening 

 sky on January 5, will attain its greatest 

 distance east of the sun on the morning 

 of February 6. For a few days before 

 and after this time it may be seen low in 

 the southwest for about one and one- 

 half hours after isunset. This is, how 

 ever, a very unfavorable elongation of 

 the planet, because it happens to occur 

 when Mercury is at that point of its path 

 which is nearest the sun. While passing 

 about its orbit, Mercury will reach the 

 point at M, Figure 3, on February 6; at 

 this time the angle S E M, the angle as 

 seen from the earth between Mercury 

 and the sun, will be the greatest. But 

 as the planet will reach the point A but 

 three days later, it is evident that this 

 angle will be an unusually small one at 

 this time. 



Mercury will reach the position N, and 

 so oass to the right of the sun and be- 

 come a morning star on February 21. 

 On the evening of February 1 it will 

 be very near the bright planet Jupiter ; it 

 will then lie to the right and above this 

 planet, being separated from it by a dis- 

 tance about equal to the moon's apparent 

 diameter. The two bright objects will 

 then form a most interesting sky figure ; 

 but, unfortunately, they will be very low 

 in the southwest and will set soon after 

 sunset at this time. 



Venus is still a most brilliant object in 

 the morning sky. It reaches its greatest 

 distance west of the sun on February 6, 

 rising at this time about three hours be- 

 fore sunrise. It is now far below the 

 equator and must therefore be looked for 

 well toward the south of the east point 

 of the horizon. 



Both Mars and Jupiter are too near the 

 sun to be satisfactorily observed during 

 this month. The former is in the morn- 

 ing sky, rising but a few minutes before 

 sunrise on February 1, which time is in- 

 creased to 45 minutes by February 28. 

 The latter toward the beginning of the 

 month sets far toward the southwest, one 



