154 



THE GUIDE TO NATURE 



after having been hidden for a greater 

 or less length of time, depending upon 

 their position. 



As seen from Washington, the cen- 

 ter of the moon will move along the 

 path AB, and all stars lying between 



Figure 3. The Pleiades as they appear in an opera 

 glass. 



the lines MP and NR will be occulted. 

 It should be carefully borne in mind, 

 however, that this appearance varies 

 with every change in the position of 

 the observer upon the earth. Our satel- 

 lite is so near us that an observer south 

 of Washington will see its path pro- 

 jected higher among the stars, while to 

 observers in the northern parts of our 

 country the moon will appear lower 

 down. Thus to an observer whose 

 latitude is 42 degrees the lines MP. BA 

 and NR will be depressed so far that 

 the bright Electra will entirely escape 

 occulation, while to one so far north 

 as 49 degrees Alcyone will always lie 

 above the moon. 



In Figure 2 the moon is shown in 

 two different positions. In the first its 

 advancing edge has just touched the 

 star Merope, whose disappearance will 

 occur at 4 hours 10 minutes A. M. El- 

 ectra, whose occulation began at 3 

 hours 36 minutes, is seen still hidden, 

 but this star will emerge 18 minutes 

 after Merope has disappeared. In the 

 second position Atlas and Pleione are 

 seen just emerging at about 7 A. M. 

 These disappear at 5 hours 53 minutes 

 and 5 hours 58 minutes, respectively, 

 while the eastern heavens is already 

 bright with the coming dawn. Since 

 at their emergence the sun will have 

 risen this part of the phenomenon can- 

 not be witnessed except in the largest 



telescopes. Alcyone, the brightest star 

 of all, will be hidden at 5 hours o min- 

 utes A. M. and will reappear i hour 7 

 minutes late. 



This most interesting phenomenon 

 can only be viewed in the telescope. 

 The observer should, if possible, pro- 

 tect the object glass from unnecessary 

 moonlight by affixing a long blackened 

 tube to the end of the instrument. Even 

 then, if his lens is a small one, he may 

 have difficulty in seeing the disappear- 

 ance of the stars which are fainter than 

 Alcyone ; their reappearance at the dark 

 edge of the moon is much more easily 

 observed. 



The Planets in October. 



Mercury enters the morning sky on 

 October 5 and reaches its greatest dis- 

 tance west of the sun on October 20. 

 For a few days before and after the 

 latter date it may be detected shining 

 low in the southeastern dawn for about 

 one hour before sunrise. 



Venus, which attained its greatest 

 distance west of the sun on September 

 12, is now slowly drawing nearer the 

 sun's rays and also moving rapidly 

 southward among the stars. On Octo- 

 ber I it will rise in the northeast about 

 three and one-half hours before sunrise, 

 and on October 31 it will rise two and 

 three-quarter hours before the sun, al- 

 most at the east point of the horizon. 

 It is the brightest object in the early 

 morning sky. 



]\Iars during the month runs rapidly 

 eastward and southward among the 

 bright stars of Scorpio ; it will finally 

 pass Antares on November 11. The 

 sun, however, in its own, more rapid, 

 eastward motion is steadily overtaking 

 the planet. The latter's position, low 

 in the southwest, its proximity to the 

 stm's rays, and its great distance from 

 the earth, all combine to render the 

 conditions for its observation very un- 

 favorable. 



Jupiter shines brightly in the east, 

 in excellent position for observation. 

 The i)lanet is slowly retrograding in the 

 extreme northwestern border of Cetus. 

 It will come to opposition, and so be on 

 the meridian at midnight, at 2 A. M. of 

 October 24. 



Saturn is in the western border of 

 Cancer, almost in a straight line with 



