20 



THE GUIDE TO NATURE 



The Planets in June. 



Mercury enters the niorning sky on 

 June 5 and reaches its greatest western 

 elongation on June 30. During the last 

 few days of the month it may 'be seen 

 low in the northeast for a little more than 

 one hour before sunrise. 



Venus runs very rapidly into the sun's 

 rays during the month, and, though still 

 a conspicuous object on June i, it will 

 become completely invisible by three 

 weeks later. During this time it may be 

 seen in the telescope to be very rapidly 

 taking the form of the narrowest imagin- 

 able silvery crescent, the apparent diam- 

 eter of which is at the same time grow- 

 ing rapidly greater as our sister world 

 draws nearer to us. This interesting 

 change of form can be viewed even in a 

 very small telescope. Venus will enter 

 the morning sky on July 3. 



Mars will run rapidly eastward through 

 Leo during the month and so will con- 

 tinue to shine conspicuously in the west- 

 ern heavens. Its distance from us is, 

 however, so great that it is a disappoint- 

 ing dbject in the telescope. It now resem- 

 bles in shape the moon when about three 

 days past the first quarter. 



Jupiter rises about 2 hours and 30 

 minutes before sunrise on June i, but this 

 time is increased to four hours by June 

 30. It will be found almost directly above 

 the east point of the horizon. 



Saturn, as shown in Figure i, is mov- 

 ing slowly eastward in the constellation 

 Gemini. In its eastward motion it will 

 pass very close to the bluish, third mag- 

 nitude star at L, and its motion from 

 day to day (though this is necessarily very 

 slow, may be clearly observed bv a com- 

 parison with this star. The two objects 

 will be nearest together on Tune 20. nt 

 which time they will be indistinguishable 

 to the eye, though in the telescope it will 

 be seen that the plane is 2 minutes and 

 33 seconds above the star. The star itself 

 is an interesting double, having an eighth 

 magnitude companion in very slow mo- 

 tion around it and onlv seven seconds 

 away. Saturn will pass to the west of 

 the sun and so become a mornino- star 

 on Julv T2. During- the early days of 

 Tune, however, it will still form a verv 

 interesting object in the telescooe. for the 

 rings at the present time are verv widelv 

 opened. 



***** 



The Longest Dav. 



On June 21, at i hour 24 minutes P. M. 



(Eastern standard time J, the sun will 

 attain its highest position in the heavens ; 

 at this instant its upward motion among 

 the stars will cease and its downward 

 motion will begin. This instant will 

 therefore mark the beginning of summer, 

 and June 21 will be the longest day of 

 the year. 



The So-called "New Planet." 

 A cablegram from Germany printed in 

 many of the papers on May 3 announced 



Figure 3. A photographic telescope. 



the discovery of a new planet on April 

 17, though it subsequently appeared that 

 this object had been seen at the Yerkes 

 Observatory some two or three days 

 earlier. This body was not similar to one 

 of the great planets which revolve about 

 the sun, but merely one of the numerous 

 planetoids, or asteroids, which move 

 in a zone between the orbits of Mars and 

 Jupiter. Many of these little bodies are 

 discovered each year, the total number 

 now known being no less than 840. They 

 are searched for by photography. The 

 photographic plate is either kept fixed 

 with reference to the stars, in which case 

 the moving asteroid photographs itself 

 upon the plate as a short trail, or line of 

 light, while the star images are points ; 

 or else the plate is moved steadily at about 

 the rate at which the asteriod moves. In 

 the latter case the star images are all 



