378

THE PLANET SATURN.

As seen from the planet, the position and appearance of theRings would greatly vary, both with the season of the year andwith the locality of the observer. Since they lie in the planeof the planet’s equator, they would only show their bright sidesto a resident upon Saturn during the interval between a springand an antumn equinox of the hemisphere upon which he mighthe; which interval would, however, last for about 14f consecu-tive years. Nor would they at any time appear to be of uniformbreadth, for it is evident that, owing to Saturn ’s great diameterand their nearness, the portion furthest from the horizon wouldhe much the closest to an observer, and would, therefore, ap-pear to be so much the broadest. Moreover, they would seemto meet the horizon in points nearer to the east and west thanwould be the case with a circle of the celestial sphere describedround the pole of the heavens visible to the observer, and drawnthrough their highest point above the horizon; i.e., such a circleas the Sun, or a star, if it passed through that point when onthe meridian, would describe in its daily course across the sky.It also follows that the arch formed by them would in generalappear to be, not of a circular, but of an elliptical shape. Atthe equator only would it be a vertical arch of small width, butvery considerably wider overhead than on the horizon; in whichspecial case, although its outer boundaries would seem to besomewhat elliptical, its central section would appear to becircular.

That the above statements are a necessary result of therelative positions of the planet and of the rings, may be under-stood by a few moments’ careful thought; or they may beillustrated by actually making a rough model of Saturn witha ball, or globe, and a ring ; but in order to demonstrate themfully mathematical calculations would be necessary, intowhich we cannot enter here. The diagram in Fig . LXXXVII.may, however, to some extent illustrate the appearance whichthe rings would present, as seen from a place upon the planet,having a North Latitude of about 30°.

It shows, in accordance with our statements, that both theouter (and narrower) ring a and the inner ring b (which wouldapparently lie one above the other upon the sky), one-half of