POPULAR ASTRONOMY. 



321 



THE HEAVENS IN DECEMBER. 



BY GARRETT P. SKKYISS, BROOKLYN., N . V. 



Saturn remains the only conspic- 

 uous planet in the evening sky, for 

 Neptune, which rises about six p. m. 

 in the middle of the month, is invisible 

 to the naked eye. Saturn sets about 

 midnight in mid-December, and all 

 through the early evening hours its 

 steady light may be seen, placidly out- 

 shining the fixed stars in its neighbor- 

 hood, although it is not as bright as it 

 appears when the rings are widely 

 opened and when their broad surfaces 

 add their reflection to the luminosity 

 of the ball of the planet. It is inter- 

 esting to remark, that Saturn is now 

 close to the Vernal Equinox and con- 

 sequently near one of the crossing 

 points of the equator and ecliptic. 

 The sun is at that point about the 

 22nd of March every year. Although 

 the rings are not widely opened they 

 can easily be seen with a small tele- 

 scope, say of three inches aperture, and 

 the spectacle that they present is one 

 of the most charming that the heavens 

 afford. Ever since their discovery the 

 rings of Saturn have excited the curi- 

 osity not only of astronomers, but of 

 all intelligent people. One of the best 

 stories about Sir William Herschel is 

 that of the image of Saturn and its 

 rings which he cut out of white paste- 

 board and fastened on a dark wall at 

 the bottom of his garden to show to 

 the king through his telescope, his ma- 

 jesty having come for a look through 

 the instrument on a cloudy night, and 

 Herschel being unwilling that he 

 should go away without seeing any- 

 thing. On account of the recent re- 

 markable discovery of a new ring in 

 the Saturnian system it may be inter- 

 esting to recall briefly what is known 

 about these wonderful objects. There 



arc three principal rings, two bright 

 and one dusky. The latter, which is the 

 nearest to the planet, is usually called 

 the Crape Ring. It is so gauze-like in 

 structure that the ball of the planet 

 can be seen through it. The two 

 bright rings are unequal in brilliancy 

 as well as in width. The outermost, 

 which is called by astronomers Ring 

 A, is, in round numbers, 10,000 miles 

 broad. It is separated by a gap 1,600 

 miles across, called the Cassini divi- 

 sion, from Ring B, which is about 

 12,500 miles broad. The inner edge 

 of Ring B blends gradually into the 

 dusk}- Crape Ring, which is called 

 Ring C. This is about 10,000 miles 

 broad, and between its inner edge and 

 the equator of the planet is a space 

 8,000 or 9,000 miles across. Notwith- 

 standing their enormous size — A is 

 168,000 miles in diameter — the rings 

 are only 100 miles thick. They might 

 be likened to a gigantic buzz saw, only 

 broad and very thin, having a wide 

 circular opening in the centre in the 

 middle of which hangs the ball of the 

 planet, itself about 75,000 miles in dia- 

 meter. The outer ring, A, has a nar- 

 row division near its outer edge which 

 can be seen like a thin black line with 

 a powerful telescope, and in October 

 this year, at the Geneva Observatory, 

 a fourth ring was detected quite out- 

 side of A. This new ring resembles 

 the Crape Ring, being dusky and 

 gauze-like in appearance. This fact is 

 of immense importance because it 

 tends to support the theory that Sat- 

 urn's rings are gradually disintegra- 

 tive. It is known both from mathe- 

 matical reasoning, and from spectro- 

 sopic evidence, that the rings are not 

 solid bodies, but are composed of mul- 

 titudes of particles, revolving indepen- 

 dently of one another, except probably 

 for mutual collisions, and all travelling 



