THE PLANETS, ARE THEY INHABITED I 



1. If the estimate of the real magnitudes of the satellites, 

 given at the conclusion of the last chapter, be admitted, their 

 probable apparent magnitudes as seen from Saturn may be 

 inferred from their distances. The distance of the first, Mimas, 

 from the nearest part of the surface of the planet, is only 

 94,000 miles, or about 2| times less than the distance of the 

 moon ; the distance of the second is about half that of the moon ; 

 that of the third about two-thirds, and that of the fourth 

 about five-sixths, of the moon's distance. If these bodies, there- 

 fore, exceed the moon in their actual dimensions, their apparent 

 magnitudes as seen from Saturn will exceed the apparent 

 magnitude of the moon in a still greater ratio than that in which 

 the distance of the moon from the earth exceeds their several 

 distances from the surface of Saturn. Of the remaining satellites, 

 little is as yet known of the seventh, Hyperion, which has only 

 been recently discovered ; and the great magnitude of the sixth, 

 Titan, renders it probable that, notwithstanding its great 

 distance, it may still appear to the Saturnians with a disc as 

 great as that of the terrestrial moon. 



2. All that has been observed respecting the remarkable 

 appearances presented by the rapidly varying phases of Jupiter's 

 moons is equally applicable to Saturn ; the spectacle, however, 

 being enriched and varied by twice the number of moons. Since 

 the first satellite changes from the thinnest crescent to the half 

 moon in five hours and a half (terrestrial), the gradual change of 

 phase must be as visible as the motion of the hand of a timepiece. 

 The second changes at a rate only one-half slower, that is, it passes 

 from a thin crescent to the half moon in eight hours. The first 

 passes from the state of the new to that of the full moon in 

 eleven, and the second in sixteen hours. The interval between 

 new and full moon for the third is twenty-two hours ; for the 

 fourth, thirty-two hours ; for the fifth, fifty-three ; for the sixth, 

 eight terrestrial days ; for the seventh, eleven ; and for the 

 eighth, forty. 



3. The eclipses, solar and lunar, produced and suffered by these 

 eight satellites are not so frequent and regular as those described 

 as taking place in the Jovian system, because Saturn's equator 

 is inclined to the sun's course at an angle of nearly 27, con- 

 siderably greater than the obliquity of the ecliptic, the conse- 

 quence of which is that the sun, at and near the Saturnian 

 midsummer and midwinter, departs to a great apparent 

 distance from the equator, to which the motion of the satellites 

 (except the eighth) is confined. For the same reason, the 

 satellites depart further from the centre of the shadow, and all 

 except the nearer ones generally move clear of the shadow in 

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