Knowledge of the Stars 163 



permits them to be well seen, and to take them up again 

 every week or two for several months and perhaps again 

 the next year. In this way, little by little you will ac- 

 quire an acquaintance with some of the brightest stars 

 and most conspicuous constellations, and this will con- 

 tinue to be a source of pleasure to you in after years. 



Reasoning as well as observation required in as- 

 tronomy. By looking through a telescope you could 

 see many stars too faint to be seen with the naked eye, 

 but even the brightest stars would appear as points of 

 light, just as they do when seen without a telescope. 

 How, then, do we know that some of them are very 

 large? Science has revealed to us many wonderful 

 things in the heavens which the ancients did not know. 

 Telescopes and other instruments are very useful to 

 the astronomers, but what is seen by means of them 

 would not afford much knowledge about the heavenly 

 bodies if the astronomers did not reason correctly from 

 the facts that they gather. The scientific method re- 

 quires not only careful observations but also careful 

 reasoning. 



The questions that are asked in the chapters that 

 treat of the heavenly bodies are intended to guide you 

 in your thinking. Many of them may seem difficult 

 to young pupils. Older students, even, will be puzzled 

 to find correct answers to some of them. It would be 

 well to give some attention to them early in your study, 

 so that, as opportunity occurs for observing the heavens, 

 some of them at least may be answered without the aid 

 of teachers or of books. 



