An introduction to astronomy: designed as a text-book for the use of students in college. By Denison Olmsted ...

210'T'1I* PL'TANEIAS.
in the lile CS at once, the planet being in ct>onjunction Awith
the sun; and, after the earth uhas passed It toward F', the
bright side of the ring is again iIn view.'.Thus, there is only a
Imomenltary disappearanllce and that when the placnet itself is
lost in thle blaze of the sun's light.
tHet il general there are two periodls of disappearance within
tfl, nodal year, arising from the tl ird/ cause (Art. 3-15), elach
btlcginillg anId ending with a disappcarlance from tlhe ijst or
secoUld cause.
347. Thle ringls of Saturn imust present a magnificcnit, spectade, to thlat henmispherl of tlhe planect to whlicll their illuminated
side is turned, aplpearing as brigt arches several dclrces in
widtlt, andt spanning the sky from one side of the hlorizon to
the other.'IThey revolve diurnally in the same planet as the
planet itself, and inll about the saime timen,:t} lhours.
34g8. Saturn is attended by e;gytt satcllites. Th.leir sizes
va.ry from 0500 to 2,850 miles;x but, on account of their great
distatnce, they arcsnccl only w\ith the best instllrumenlts. They
are all external: to the rings, and thle eighlthl at the (listance of
2,500,000 miles fi'om the planet.'t{ The seventh was (liscovered
in Cambrlidge, Mass., by Professor IBond. 11Their orbits are
nearly in th}e plane of the ring', and mnake an angle of about
28~ Awit h the orbit of the planet. Only the two interior onecs
are eclipsed, except when the ring is seen edgewise.:{
349. T.sxURus, the next. pla1net ill the series, was discovered
by Sir William Iterschel, in 1.81.:Previous to thlis time,
Saturn h]ad, firom a higlh antiquity, beenl conlsidered, as the
outermlost boundary of tlc solar system; but this discovery
doulltlc tlhe dimnensions of the system, brinlging to light a large
planct at about twice the distance of Saturn from the slun, and
about 19 times the distance of the earth, or 1800 millions of
nilcs. It was namned by the discoverer tlhe Georgian, in hbonor
of hlis patrlon, George MI!1.; but this name being unacceptable
M hilld.
-'j They have received thie nalme, Nilas, Enlcelhdus, tTcthys, Dione, RIhea,'Titaln, }ypcIionl, al nd Japetus.: Sir J. teilschcel.