24 



THE GUIDE TO NATURE 



risen in the east, while \ ega, the Eagle, 

 and the beautiful Northern Cross have 

 now completely entered the evening- sky. 

 As the months go by, the last constella- 

 tion will swing steadily across the hea- 

 vens, reaching its highest position in 

 September and not finally sinking below 

 the horizon in an upright position until 

 the very close of the year. 



Above Vega, the constellation Her- 

 cules is now found in excellent position 

 for study. Above Hercules there is the 

 beautiful Northern Crown while, still 

 higher, the great Bootes now fills the 

 very highest area of the heavens. At the 

 point A, nearly in a straight line between 

 the stars B and C, there will readily be 

 found the wonderful cluster in Hercules, 

 a compact mass of sixty thousand stars. 

 This cloud of suns can even be seen as a 

 faint, nebulous patch of light with the 

 naked e}'e. In the region between the 

 stars H. F. and Antares, there are a great 

 many other interesting clusters (though 

 these all require a telescope to render 

 them visible) while at the point K there 

 is an interesting planetary nebula, which 

 shines as a greenish, misty, eighth magni- 

 tude star. The faint stars in the region 

 E form the group Cerebus, the three- 

 headed dog which Hercules holds in his 

 hand. 



THE PLANET AlERCrRY. 



The oberver should not fail during the 

 first days of June to find this most inter- 

 esting little planet, which is always so 

 nearly lost in the sun's ravs, because its 



Figure 2. Appearance of the planet Mercury as 

 it passes around the sun. 



present appearance is a very unusually 

 favorable one. The planet is now reach- 

 ing its greatest distance east of the sun, 

 and it happens that this month it recedes 

 from the sun an vmusually long distance. 

 Figure 2 shows the shape of the path of 

 the planet about the sun and also the tele- 

 scopic appearance of Mercury when it is 

 at various parts of its path. We always 

 view the orbit nearly edgewise, but this 

 orbit is not really a perfect circle, as in- 

 dicated in Figure 2, but the distance from 

 B to S is actually fifteen millions of miles 

 greater than that from S to D. The 



planet passes the point U, and is hence 

 seen by us at its greatest distance to the 

 left, or east of the sun, on Alay 31. It 

 is because when it reaches this position 

 the planet is at nearly its greatest dis- 

 tance from the sun in miles that we will 

 see the two bodies so far apart in the 

 sky. 



The motion of Alercury among the 

 stars during the month is shown in Figure 

 3. This figure shows the appearance of 

 the western sky at 7 P. M. on June i. 

 On this date the planet will be seen in the 

 northwest, almost vertically under the 

 Twins, above and to the left of Saturn 

 and separated from this planet by a dis- 

 tance equal to five times the apparent dis- 

 tance across the full moon. C)n this date 

 Mercury will not set until two hours after 

 sunset. 



Having found the planet, the observer 

 should have no difficulty in continuing 

 to follow it until very nearly the middle 

 of the month, by which time it will set 

 oidy one hour after sunset. On June i 

 he will see that it is exactly half full, as 

 sliown at B in Figure 2, but during the 

 ensuing days he will see it narrowing 

 verv rapidly to a thin, silvery crescent. It 

 will finally pass the position C. Figure 2, 

 and enter the morning sky, on June 17. 



THE PLANETS IN JUNE. 



On June i, \'enus may still easily be 

 seen in the morning sky, rising one hour 

 and twenty-four minutes before sunrise. 

 But this planet is both drawing nearer 

 the sun and increasing its distance from 

 the earth, so that it is daily coming into 

 less favorable position for observation. It 

 will not finally pass the sun, however, and 

 enter the evening sky until September 12. 



Mars rises two hours before sunrise on 

 June I, and this interval increases to two 

 hours and thirty minutes by June 30. It 

 is approaching the earth, and consequent- 

 ly growing steadily brighter, its bright- 

 ness now being almost exactly that of a 

 first magnitude star. It will not reach its 

 most favorable position for oliservation 

 until next February. 



Jupiter is almost on the equator and 

 near the \ ernal Equinox. By the end of 

 the month it may be seen rising due east 

 so early as eleven hours, thirty minutes 

 P. M. ' 



Saturn enters the morning sky on June 

 2S. It is too nearly lost in the sun's ravs 

 to be satisfactorily oljserved during the 

 present month. 



Uranus is in Capricornus, in the morn- 

 ing sky : Neptune is in Cancer and hence 

 low in the west. 



