1'44- Dr Olbers on the Transparence^ of Space. 



error. Supposing the stars uniformly diffused over, the sky; if 

 we represent by unity the radius of the sphere formed by the 

 mean distance of the stars of the first magnitude from our sun 

 by ^, the mean diameter of these stars, and by n^ their number 

 at this distance ; the portion of the celestial vault which they 



will occupy to our eyes, will be equal to — —. At a distance 

 from the sun equal to 2, the apparent diameter of the stars will 

 be -K ; but their number will be 4 /i : they will thus also oc- 

 cupy a space — j — upon the sphere. Thus at distances 1, 2, 3, 4, 

 5, ... 7W, the stars will always cover the same portion of theceles- 



7?.^r 71X^2 ^^^2 



tial vault; the space — r f- — j— = m ^ ■ will become m- 



finitely great, when m will become so itself, since -x- , how- 

 ever small this quantity may be, remains always an infinite mag- 

 nitude. Consequently, not only will the whole celestial vault 

 be covered with stars, but they will, moreover, be placed one be- 

 hind another, in infinite series, mutually covering each other. 

 It is evident that the same conclusions will be obtained, on sup- 

 posing the stars not only uniformly diffused in space, but dis- 

 tributed in systems, separated from each other by great inter- 

 vals. 



Fortunately for us, nature has disposed things otherwise ; 

 fortunately each point of the celestial vault does not send to the 

 earth a light Hke that of the sun. I say nothing of the bright- 

 ness and heat that would result from such an arrangement ; for 

 then, whatever would have been that brightness and that heat, 

 the Omnipotent would have put our globe and its whole organ- 

 ism in a condition to resist them. I would only speak of the 

 state of imperfection in which our astronomical knowledge must 

 then have remained. We would know nothing of the fixed 

 stars ; we should scarcely be able to discover our own sun, by 

 means of its spots ; the moon and planets would only be distin- 

 guished as more or less obscure disks, detached from a shining 

 ground of a solar brightness. 



