190 



THE GUIDE TO NATURE 



appeared into view, later both enters and 

 emerges from the planet's shadow. The 

 fourth moon is not eclipsed at all during 

 the present month. 



A glance at Figure 2 will, it is hoped, 

 make the reasons for these appearances 



Figure 2. Diagram to illustrate the phenomena of 

 Jupiter's satellites (Not drawn to scale.) 



entirely clear. Jupiter passed opposition 

 on October 24 ; that is, the sun., earth and 

 Jupiter were in the positions, S, E, I and 

 J, or in one straight line, on this date. 

 Since this time, the earth has moved for- 

 ward to the position E2, so that the great 

 shadow of Jupiter, which stretches out 

 into space directly away from the sun, no 

 longer points directly away from the 

 earth. 



It is therefore evident that a moon 

 whose path, A, B is small, as the paths of 

 the two inner moons are, will be seen to 

 pass behind the planet when it has reached 

 the point A of its path ; while still hidden 

 by the ball of Jupiter it will enter the 

 shadow, and will not be seen from the 

 earth again until it finally emerges from 

 the shadow at B. The third moon, how- 

 ever, moves in a path so large that after 

 disappearing behind the planet at C, it re- 

 appears at D, and some time later is seen 

 to pass through the shadow at E and F. 



For example, on the evening of Novem- 

 ber 16, this moon will be occulted at C at 

 4 hrs. 58 min., P. ^I. ; it will emerge from 



behind the planet at D at 6 hrs. 26 min. ; 

 it will enter eclipse at E at 7 hrs. 17 min., 

 and it will finally emerge from the shadow 

 at F at 9 hrs. 4 min., P. M. (Eastern 

 Standard Times.) Similar interesting 

 phenomena will occur on the nights of 

 November 3, 5, 10, 12, 19, 23 and 26. 



* ::= * t- :■■- 



The Planets in November. 



Mercury will not be visible during the 

 present month, for although it enters the 

 evening sky on November 24, it does not 

 attain its greatest distance east of the sun 

 until next January 3. 



A'enus is still very brilliant in the morn- 

 ing sky. It rises three hours before sun- 

 rise on November i, and this time is de- 

 creased to two and one-half hours by 

 November 30. The planet is by far the 

 most brilliant object now in the heavens, 

 shining with one hundred times the 

 brightness of a first magnitude star. 



Mars may still be seen low in the south- 

 west, where it sets about one and one-half 

 hours after the sun. The planet is now 

 far below the celestial equator and is 

 raj^idly moving still farther southward. 

 It will Dass the winter solstice on Decem- 

 ber I. Throughout the month it is in very 

 favorable position for observation. 



Jupiter is now high in the southern 

 heavens in the position shown in Figure 

 I ; it is moving southward among the 

 stars, and also retrograding, or moving 

 westward. 



Saturn, almost in a line with the Twin 

 Stars, Castor and Pollux, rises at 9 hrs. 

 30 min., and so is just behind the borders 

 of our evening map. Toward midnight 

 it is hiofh in the heavens in excellent po- 

 sition for observation. 



A Distant Comet. 



There is a most interesting comet now 

 in the skv which was discovered on a pho- 

 tographic plate so long- ap'o as April 2"/ of 

 the Drc^ent year. At that time it was 

 nearlv 400,000,000 miles away from us 

 — almost as far away as the planet Jupiter, 

 and it consequently appeared extremely 

 faint. But the fact that it could be seen 

 at all at so great a distance leads us to be- 

 lieve that it must be a very unusually 

 large and bright object. Since its dis- 

 covery it has been steadily approaching 

 the suui ; it will not attain its least distance 

 from that body, however, until next June. 



