340 



THE GUIDE TO NATURE 



Virgo) is of special interest, not only 

 because the orbit or path of one of the 

 stars about the other is well deter- 

 mined, but also because each of them 

 varies in brightness. The period of a 

 •couiplcte revolution about the orbit is 

 about 193 years, but each star dimin- 

 ishes about half a magnitude in bright- 

 ness and recovers again in the course 

 of i:)ul a few days 



The observers should also examine 

 the rtiost brilliant stars of the heavens, 

 noting their distinctive colors and their 

 comparative brightness. Thus the 

 great Arcturus, at H, many thousands 

 of times brighter than our sun, is of a 

 reddish-yellow color ; the fainter Spica, 

 at I, that wonderful sun which is cease- 

 lessly revolving about a dark and invis- 

 ible companion with a speed of fifty-six 

 miles a second, is a white star, while 

 V^ega, at K, the brightest star of the 

 northern heavens is of a decided blue. 

 The beautiful Regulus, at L, is a white 

 star but due east of it at a distance of 

 three minutes it will be found to have 

 a faint little companion which is of an 

 intense blue. 



The Planets in April. 



The bright, but difficult little planet 

 Mercury will attain its greatest dis- 

 tance east of the sun on April 24, and 

 tnay be seen for a few evenings before 

 and after this date shining well toward 

 the northwestern part of the horizon 

 b)Ut low in the twilight glow. On the 

 ■evening of elongation it will not set 

 until one and one-half hours after sun- 

 set. 



On April 16 the planet Jupiter, which 

 IS now drawing so close to the sun, will 

 be passed by Mercury in its eastward 

 motion, the two worlds then being 

 three degrees apart in the sky and Mer- 

 cury being north of Jupiter. This in- 

 teresting conjunction may be viewed 

 without much difficulty, especially if 

 the telescope of the observer is fur- 

 nished with setting circles, but espe- 

 cial care must be used as on this even- 

 ing both of the planets set less than one 

 hour after sunset. 



Venus during the first part of the 

 month is in the morning sky, but it will 

 change to an evening star on April 26 

 at 3 A. M. During the entire month, 

 however, it is too completely lost in 

 the sun's ravs to be observed. 



IMars is very slowly withdrawing 

 from the sun into the morning sky. 

 Since on April i it rises but twenty- 

 two minutes before sunrise and on 

 x\pril 30 but forty minutes before the 

 sun it is, however, too wholly lost in 

 the sun's rays for satisfactory observa- 

 tion. 



The planet Jupiter, although during 

 the first part of the month it may be 

 seen in the northwest for a short while 

 after sunset, is rapidly leaving the 

 evening heavens and toward the close 

 of the month will be too close to the 

 sun to be observed. This planet will 

 pass to the west of the sun and become 

 a morning star on Alay 9. 



Saturn still remains in excellent po- 

 sition for observation and will be seen 

 shining high in the western heavens in 

 the southern borders of the constella- 

 tion Gemini. The rings of this planet 

 are now widely opened out, and it fur- 

 nishes a beautiful object for observa- 

 tion in the telescope. 



The Occultation of Omicron Leonis. 



In the course of its monthly journey 

 around the celestial sphere among the 

 stars the moon is continually passing 

 over the fainter stars in its path and 

 hiding them from our view. During 

 the first months of the present year it 

 happens that very few bright stars 

 are thus occulted as seen from the east- 

 ern United States ; on April 2, however, 

 an occultation of the quite bright star 

 at M. Fig. I, may be witnessed and the 

 phenomenon will furnish a very inter- 

 esting subject for observation. 



At this time the moon is three days 

 past the first quarter, of approximately 

 the form shown in Fig. 3, so that it is 

 its dark portion that is to the east or 

 advancing edge. As seen from Wash- 

 ington this edge will reach the star and 

 cause it to disappear at 10 hrs. 35 min. 

 P. M. ; the reappearance will occur at 

 II hrs. 39 min. (Eastern Standard 

 Time) so that the star will be hidden 

 for one hour four minutes. These times 

 will vary greatly however, as the phe- 

 nomenon is viewed from different sta- 

 tions ; observers further north on the 

 earth will see the moon pushed further 

 downward among the stars, while to 

 those south of Washington the posi- 

 tion of the moon in the sky will be 

 higfher. The observer should therefore 



