THE SUN. 69 



The common observation of every one who directs his view to the heavens, 

 will inform him of the fact that the sun and full moon appear to be of the same 

 size. The mere effect of ordinary visual observation is, perhaps, enough to 

 establish this ; but if more be desired, instruments expressly adapted to meas- 

 ure the apparent magnitudes of objects may be applied. We are also con- 

 firmed in the fact by the consideration of the well-known phenomena of solar 

 eclipses. A solar eclipse is produced by the interposition of the globe of the 

 moon between the eye and the globe of the sun. The eclipse is said to be 

 central when the centre of the moon is directly in line between the eye and 

 the centre of the sun. When this takes place we find that the globe of the 

 moon generally covers, pretty exactly that of the sun. Owing, however, to a 

 slight variation in the apparent size of these bodies, from a cause that we shall 

 explain on another occasion, the moon at one time a little more than covers the 

 sun and at another time a little less. In short, the average apparent magnitude 

 of these bodies are the same, the one exactly covering or concealing the other. 



But we have already stated that the distance of the moon is only a quarter 

 of a million of miles. It appears, then, that the distance of the sun is four 

 hundred times greater than that of the moon ; yet these two globes appear to 

 the eye to be of the same magnitude. The sun, notwithstanding its being four 

 hundred times farther off, appears just as large as the moon. What, then, are 

 we to infer respecting its real magnitude ? If the sun were really equal in 

 magnitude to the moon, it would assuredly appear four hundred times less at four 

 hundred times a greater distance : but as at that greater distance it does not ap- 

 pear less or greater, but of the same magnitude, the irresistible conclusion 

 level to the apprehension of any understanding, is, that the sun must in reality 

 be four hundred times greater in its diameter than the moon. If it were less, 

 at four hundred times the moon's distance, it would appear less than that of the 

 moon ; if it were greater, at that distance it would appear greater. It follows, 

 then, that whatever be the magnitude of the diameter of the moon, the diame- 

 ter of the sun must assuredly be four hundred times greater. Now it has been 

 ascertained by absolute measurement that the diameter of the moon measures 

 about two thousand miles. If we multiply this by four hundred we shall ob- 

 tain eight hundred thousand miles, which is, therefore, the diameter of the sun. 



These calculations have been made roughly and in round numbers ; more ac- 

 curately, the diameter of the sun measures 888,000 miles, but as we recom- 

 mend the adoption of round numbers, we shall call the sun's diameter 

 900,000 miles. Such is the stupendous mass placed in the centre of the sys- 

 tem which, by its attraction, coerces the movements of the planets. 



Such magnitudes are so far beyond all the ordinary standards with which we 

 are familiar, that the imagination is confounded in its efforts to form to itself any 

 distinct conception of them. Let us see whether we may not find some illus- 

 tration which will aid the understanding in conceiving the dimensions of this 

 immense globe. We know that the earth is a globe whose diameter is eight 

 thousand miles, and that the moon holds its monthly course around it at the dis- 

 tance of about a quarter of a million of miles. Let us suppose the centre 

 of the earth at E., placed at the centre of the sun. Let the moon, M., 

 hold its monthly course around it, the distance from M. to E. will then be 

 about two hundred and fifty thousand miles, but the surface of the sun. S., is 

 at a distance from its centre E. a little less than four hundred and fifty thou- 

 sand miles. Consequently it follows that the earth and its moons would thus 

 be not only continued within the globe of the sun, but the surface of the sun 

 would even then be two hundred thousand miles outside the monthly orbit oi 

 the moon. The sun would, in fact, contain the moon and earth within it, and 

 have a couple of hundred thousand miles to spare ! 



