Recognizing the Stars [ 409 



enormous that it can continue to shrink at its present rate for 

 billions of years without affecting the earth! 



SAFETY MEASURES FOR SUN OBSERVATION 



If you are interested in sun-watching, you must always 

 keep in mind how dangerous it is to look directly at it, even for 

 a moment. To impress this on your child, you can hold a reading 

 glass in the sunlight so that it will focus the rays on a piece of 

 paper. Before long a hole will burn in the paper a dramatic il- 

 lustration of the power of the sun. 



As for using an instrument, anyone looking at the sun through 

 a telescope not equipped with a darkened lens, would be blinded. 

 Observing the sun is safe only with a proper telescope, or heavily 

 smoked glass, or several thicknesses of photographic film. 



For interesting and easily managed sun observations, you can 

 note and record the time of sunset and sunrise over a period of 

 several months and also the points on the horizon at which the 

 sun rises and sets during the same period. In this way you have 

 first-hand information about its gradual shift northward (as seen 

 from northern latitudes) from December 2 1 to June 2 1 ; you can 

 then chart its reverse trip southward from June 2 1 to December 2 1 . 



Stars Beyond the Sun 



The sun is four hundred times farther away from us than is the 

 moon. Yet the sun, in comparison to the other stars, is a nearby 

 star! that is why it appears large and red. This fact will give a 

 youngster some notion of the incredibly vast distances between us 

 and the other stars. 



The average size of a star is about equal to the size of the sun. 

 Many stars that we can see with unaided eye are much larger than 

 the sun; on the other hand, countless stars that can be seen only 

 through telescopes are smaller than the average size. 



HUNDREDS OF THOUSANDS OF LIGHT-YEARS AWAY 



The real stars (as distinguished from the wandering plan- 

 ets) we know as "fixed" stars. Scientists have reckoned that light, 



