THE NUMBER OF THE STARS. 



113 



we do not realize how faint the great majority of the stars are 

 as they appear to iis, we shall not understand how distant they 

 must be, and how great must be that universe which can 

 contain bodies really so vast and so intensely bright, and 

 yet, on account of their distance, apparently so extremely 

 faint. 



The table given earlier showed how ra])idly the number of 

 faint stars increases, as we go from magnitude to magnitude in 

 the order of decreasing brightness. Their greater faintness, 

 combined with their enormously increased numbers, allows of 

 two possibilities. Does the increase in number as we proceed 

 from one magnitude to the next fainter make the total bright- 

 ness of eacli fainter class of star increase, so that the number 

 of stars between one magnitude and the next may be sufficient, 

 in spite of the increased faintness of each star, for their total 

 light to exceed the total light of the magnitude one higher up, 

 or does it make it diminish ? The table gives the answer to 

 this question by showing the number of stars of the 1st 

 magnitude which would give an equal amount of light with the 

 stars of each successive fainter magnitude. Stars of the 1st 

 magnitude are the brightest of those that we see by the 

 unassisted sight, and of these a few ore really considerably 

 brighter than the average 1st magnitude star. The brightest 

 star is Sirius, which gives eleven times as much light as a 

 typical star of the 1st magnitude. Then comes Canopus, 

 giving six times the light of a 1st magnitude star, and Alpha 

 Centam^i, our nearest neighbour in the stellar depths, which is 

 equal to two 1st magnitude stars. Eight stars follow down tO' 

 the typical 1st magnitude star which together are ecpial in light 

 to fourteen stars of the 1st magnitude, twenty-seven stars 

 between the 1st and 2nd magnitudes, give an amount of light 

 equal to seventeen stars of the adopted standard, and seventy- 

 three stars between the 2nd and 3rd magnitudes are equal to 

 eighteen stars of the standard magnitude. As the table is 

 followed downward, it will be seen that the equivalent light 

 given by eacli succeeding magnitude increases till we reach 

 the 10th magnitude, after which it begins to diminish. Thus 

 some idea can be formed of the extreme faintness of these 

 fainter stars. Two million stars between the 12th and 13th 

 magnitudes only give light equal to fifty-one of the standard 

 1st magnitude, and as we pass to still fainter stars, twenty-tive 

 millions between the IGtli and 17th magnitudes are only equal 

 to sixteen standard stars. 



Beyond the 17th magnit-ude, the numbers are not derived 



I 



