Sky Study 



903 



Arclurus and the Big Dipper. 



lowing its own curve for about 



twice its length and it will end 



in a beautiful, yellow star, the 



only very bright one in that 



region. It is a thousand 



times brighter than our own 



sun, but its light does not 



reach us for a hundred years 



after it is given off. Arcturus 



is supposed to be one of the largest of all the suns, having a diameter of 



severai millions of miles. During the latter part of June and July it is 



almost overhead in the early evening. 



The Crown 

 Between Arcturus and Vega, but much nearer the former, 

 is a circle of smaller stars that is called the Northern Crown, 

 and which because of its form is quite noticeable. 



Spica {spi'-ka) 

 Place on the blackboard the Big Dipper, the Pole-star, the 

 line F and Spica. To find Spica draw a line through the star 

 on the outer edge of the top of the bowl of the Big Dipper, 

 through the star at the bottom of the bowl next the handle, 

 and extend this line far over to the southwest, during the even- 

 ings of June and July. (See page 901) In August, this star 

 o'clock. Spica is a white star, and is the only bright one in that 

 sky. It is so far away from us that the distance has never been 

 Spica is in the constellation called the Virgin. 



The North- 

 ern Crown. 



sets at ten 

 part of the 

 measured. 



Vega (vee'-ga) 

 Place on the blackboard the Pole-star, the Big Dipper, 

 the lines H and I and Vega with her five attendant stars, 

 as shown in the chart. Teach that these stars are the 

 chief ones in the constellation called The Lyre. To find 

 Vega, draw a line from the Pole-star to the star in the Big 

 Dipper which joins the bowl to the handle. Then draw a 

 line at right angles to this (see chart lines H, I) and extend 

 the line I a little farther from the North-star than is the 

 end star of the Dipper handle ; this line will reach a bright 

 star, bluish in color, which can always be identified by four 

 smaller attendant stars which lie near it and outline a 

 parallelogram with slanting ends. Vega is the most 

 brilliant summer star that we see in the northern hemi- 

 sphere. It is a very large sun, giving out ninety times as 

 much light as oxrr sim; it is so far away that it requires 

 twenty-nine years for a ray of light to reach us from it. Vega's chief 

 interest for us, aside from its beauty, is that toward it our sun and all its 

 planets, including oiu: earth, are moving at the rate of thirteen miles per 

 second. 



Vega and her train 

 of five stars. 



