THE STELLAR UNIVERSE. 



about one hundred and seventy million times the distance of the 

 sun ; and since the distance of the sun expressed in round numbers 

 is one hundred millions of miles, it will follow that the distance of 

 such a star is seventeen thousand billions of miles. 



"We arrive, therefore, at the somewhat astonishing conclusion 

 that the distance of these objects, the existence of which the 

 telescope alone has disclosed to us, must be such that light, 

 moving at the rate of 192000 miles per second, takes upwards of 

 2600 years to come from them to us, and consequently that the 

 objects we now see are not those which now exist, but those 

 which did exist 2600 years ago ; and it is within the scope of 

 physical possibility that they may have changed their conditions 

 of existence, and consequently of appearance, or even have ceased 

 to exist altogether, more than 2000 years ago, although we 

 actually see them at this moment. 



This incidentally shows that the actual perception of a visible 

 object is no conclusive evidence of its present existence. Jt is 

 only a proof of its existence at some anterior period. 



It appears, then, that there are numerous orders of stars, which 

 by reason of their remoteness are invisible to the naked eye, but 

 which are rendered visible by the telescope ; and these stars are, 

 like those visible to the naked eye, of an infinite variety of 

 degrees of magnitude and brightness, and have accordingly been 

 classed by astronomers according to an order of magnitudes in 

 numerical continuation of that which has been somewhat indefi- 

 nitely or arbitrarily adopted for the visible stars. Thus, suppos- 

 ing that the last order of stars visible without telescopic aid is 

 the seventh, the first order disclosed by the telescope will be 

 the eighth, and from these the telescopic stars, decreasing in 

 magnitude, have been denominated the ninth, tenth, eleventh, 

 &c. to the sixteenth, or seventeenth magnitude, the last being the 

 smallest stars which are capable of being rendered distinctly 

 visible by the most powerful telescope. 



Besides bringing within the range of observation objects placed 

 beyond the sphere which limits the play of natural vision, the 

 telescope has greatly multiplied the number of objects visible 

 within that sphere, by enabling us to see many rendered invisible 

 by their minuteness, or confounded with others by their apparent 

 proximity. Among the stars also which are visible to the naked 

 eye, there are many, respecting which the telescope has disclosed 

 circumstances of the highest physical interest, by which they 

 have become more closely allied to our system, and by which it is 

 demonstrated that the same material laws which coerce the planets, 

 and give stability, uniformity, and harmony to their motions, 

 are also in operation in the most remote regions of the universe. 

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