286 



THE GUIDE TO NATURE 



its highest position in the southern 

 heavens early in June. 



This wonderful star is one of the 

 most remarkable objects in the great 

 cloud of stars around us. Its great 

 brilliance does not arise from its near- 



stars are many remarkable though faint 

 nebulas and which is remarkable also 

 for the large number of double stars 

 of contrasting colors which it contains. 

 To the Arabians this faintly shining 

 area of the sky was the Pond, into 



1-lgUl'l- 2. 



if March 22. 



-Passage of the mc on through the earth's 



hadow 



tin- moraine 



ness to us ; in fact, it is so very far 

 away that its distance cannot be direct- 

 ly measured by any instrument which 

 we at present possess, and it is there- 

 fore evident that its intrinsic light and 

 heat must be many thousands of times 

 as great as those of our own sun. And 

 yet, in spite of its inconceivably great 

 distance away from us, this great sun 

 is rushing along through the depths 

 of space with such remarkable speed 

 that in only a very few years its change 

 of position upon the celestial sphere can 

 easily be observed, even in a very small 

 telescope. This drift of Arcturus 

 among the stars is so great that in only 

 800 years its position is changed an 

 amount as great as the apparent dis- 

 tance across the full moon. But very 

 few even of the stars nearest to us 

 have an apparent motion so large as 

 this, and when the great distance away 

 of Arcturus is considered, it is evident 

 that so great a displacement must arise 

 from a real motion of hundreds of miles 

 a second. 



Between Arcturus and the Lion there 

 is the delicate little group known as 

 Coma Berenices, among whose faint 



which their Gazelle was springing to 

 escape from the Lion, the group of 

 stars called by them the Gazelle being 

 those faint stars lying between the 

 Great Bear and Leo, and known to us 

 as the Lesser Lion. 



This continual change in the face of 

 the heavens, the constellations seeming 

 to draw ever westward toward the sun, 

 is due in. reality to the fact that as seen 

 from our moving earth the sun appears 

 to pass steadily across the sky, com- 

 pleting the circuit in exactly one year. 

 During the coming months the center 

 of the sun will move along the path 

 VEK of Figure i, reaching its greatest 

 distance above the celestial equator 

 while in the constellation Gemini on 

 June 21 and crossing to below the equa- 

 tor at the point E on September 23. 

 The sun in its eastward motion has 

 now nearly reached the point of the 

 heavens which is exactly opposite to 

 E; this is the point occupied by the 

 center of the sun as it crosses the equa- 

 tor in passing from the southern to 

 the northern hemisphere. The sun will 

 reach this point at 18 minutes past mid- 

 night on March 21 (Eastern standard 



