HOW FAR AWAY ARE THE STARS? 195 



stars once now have so little light and heat that they do 

 not even glow. They have become cold bodies like our 

 earth and our moon. The color band and its position as 

 seen in the spectroscope help astronomers to tell whether 

 the star is moving away from us or coming toward us. 



SELF-TESTING EXERCISE 



Select from the following list the words that best fill the blank spaces in 

 the sentences below and arrange the words in proper numerical order. 

 A word may be used more than once. 



million years red color 



tenth month black photography 



first century white periscope 



thousand Heavens light telescope 



100 orange dark sixth 



year yellow stars fourth 



More stars in the (1) are discerned by (2) than can be 



seen through a (3) (4) . travels faster than any other 



known thing. In astronomy the unit of measure for distance is 



the (5) (6) , which equals six (7) (8) miles. The 



nearest star is about 4^ (9) (10) away. The faintest 



star we can see is a (11) magnitude star. A first magnitude 



star is (12) times as bright as this. The age of a star is told 



by its (13) Young stars are (14) , while old stars are 



(15) or (16) 



STORY TEST 



URSULA VISITS A GREAT OBSERVATORY 

 Read carefully and critically. List all the errors and suggest corrections. 



I recently enjoyed a rare privilege. It was open night at the 

 Harvard Astronomical Observatory. Through a 10 in. tele- 

 scope I saw the red Rigel and red Mars. Rigel is ever and ever 

 so much hotter than our sun and the other stars. As I looked at 

 it I could feel the intense heat coming through the telescope, and 

 no wonder, because it is 25,000 times as hot as the sun. I asked if 

 I might see the astronomer's "yard stick" with which they meas- 

 ured the distance to the stars. I wonder why they laughed, but 

 anyway they said that they never let the public see it. On one 

 of the roofs without any telescope we were shown constellations 



