M. Arago on the Physical Constitution of the Sun. 205 



*' It is a star, only it surpasses in size all the other stars." 

 The conjecture, for what is not based upon any measurement, 

 or any observation, deserves no other name, was certainly 

 very bold and very beautiful. Let us pass over an interval 

 of more than two thousand years, and we shall find the rela- 

 tion of the sun and the stars established by the labours of 

 the moderns, upon a basis which defies all criticism. 



During nearly a century and a half, astronomers endea- 

 voured to determine the distance between the stars and the 

 earth ; the repeated failures with which their researches 

 were attended, seemed to prove that the problem was insolv- 

 able. But what obstacles will not genius, united to perseve- 

 rance, overcome? We have discovered within a very few years 

 the distance which separates us from the nearest stars. This 

 distance is about 206,000 times the distance of the sun from 

 the earth, more than 206,000 times 95 millions of miles. 

 The product of 206,000 by 95 millions, would be too much 

 above the numbers we are in the habit of considering, to 

 warrant its annunciation. 



This product will still more strike the imagination, when I 

 refer to the rapidity with which light travels. Alpha, in the 

 constellation of the Centaur, is the star nearest the earth, if it 

 be allowable to apply the word near to such distances as 

 those of which I am about to speak. 



The light of Alpha, of the Centaur, takes more than three 

 years to reach us, so that were the star annihilated, we 

 should still see it for three years after its destruction. Re- 

 cal to your recollection that light travels at the rate of 

 192,000 miles in a second ; that the day is composed of 

 86,400 seconds, and the year of 365 days, and you will feel 

 as thunderstruck before the immensity of these numbers. 

 Furnished with these data, let us transport the sun to the 

 place of this, the nearest star, and the vast circular disc, 

 which in the morning so majestically rises above the horizon, 

 and in the evening occupies a considerable time in descend- 

 ing entirely below the same line, would have dimensions 

 almost imperceptible, even with the aid of the most powerful 

 telescopes, and its brilliancy would range among the stars of 

 the third magnitude. You thus perceive what has become 

 of the conjecture of Archelaus. 



