192 Trees, Stars, and Birds 



and in this way tell the directions on a clear night. 

 Distances in degrees may be estimated by remembering 

 that from the horizon to the zenith is 90 degrees. 

 Shorter distances may be estimated by comparing 

 them with parts of the Great Dipper. The Pointers 

 are 5 degrees apart, and from the nearer one to the 

 North Star is a little less than 30 degrees. The open 

 part of the Dipper bowl is 10 degrees across ; the handle 

 is 1 6 degrees long. Study these distances until you are 

 able to estimate accurately a given number of degrees 

 on the celestial sphere. 



Light from the North Star. Although brighter than 

 any star near it, the North Star is much surpassed by 

 stars in other parts of the heavens. It is a second- 

 magnitude star and not nearly so bright as stars of the 

 first magnitude. In recent years telescopes have 

 been constructed that photograph stars as faint as the 

 twentieth magnitude. About fifteen millions of such 

 stars would be required to give as much light as the 

 North Star. Most stars are more distant than the 

 North Star, but some stars are nearer. Light traveling 

 at the rate of 186,330 miles a second requires 44 years 

 to come from the North Star ; so, if it had been 

 eclipsed 40 years ago by some dark body near it, 

 4 more years would pass before we would know of the 

 eclipse. 



The Little Dipper. When 'asked to point out the 

 Little Dipper, people are likely to find such figures in 

 different parts of the heavens. The only figure properly 

 called the Little Dipper is in the north, in the constella- 

 tion of Ursa Minor or the Lesser Bear. The North 



