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

iiIKVt ift_.i ION.,S K 1 125
a weartUlisomle sumeilmner; each nighlt a severe wvinter.'' A spectator on the s'ide of thle mooll whlicl i opl))osite to ius vwould
\never sc tlhe c1arttt; but ole onl the sitle llext to us would sec
the earth t presentingll a grasdual succession of changelt s ldurinlg
]tis long nllight of 36O t)ours. Soon aftcr thc carth l's cot0jijuction withl thle sun, lhe would ha've the liglht of the eartht retlected to litln, preslnting at first t cresccnt, but tltarginllgt, as
the eartltl1 approac-les its oppolsitionll, to a great orb,:13 times as
lartg as the full mnoon appears to Qus, and aftlordll,; neiarly 13
tiimes ls ltelt l igllt. O)ur seas, plains, mountains, atnd clouds,
would presenlt'l great tiversityt of appcarance, as thle cart
perfortled its diurnal rotation; thollugl tlhe distinlettess woulld
be nmucll impllaired by the strong light rellect-ed by our atmtospherel. le earth to his view -would remai-nl a.tlways itL the
same. prt qf the sky, having only slmall monlthly oscillations,
north and soulltll by meantl1s of tthe libration in latitude, also
east and west, by tle libration in lonlitude. For, being unconseious of h]is own motion atround tihe earth, it would seentl
to revolve about hlis planct fiomt west to ecast; but, lmeanwhile,
his own diurnal rlotation -would give the eartl an aplparent
lotion to ti-e west at the saml1e imean rate, and the two would
balance caclt other, cxccept so far as the librations would affekct
themn. An observer oil the center of thie miioon's diskl, Vwoulld
see tlhe earth always over hread; onle at the edge of tlhe dislk,
would see it at the horizon. The eartlt is full to tlhec mtoon
whelc the latter is new\ to us; and universally tce two p)hases
tlare comllplelmetary to cath other.
221. If thel ecliptic (the earth's pathl about th.} sun), and
tlhe n1ooll's pltll about til earth, w ere visible lines ill ttle sky,
since we 1are iii the pllane of each, ttecy wvould botlt al)pear as
great circlces intersecting eac]h othier in opposite points, tand inelined tabout 50 to eachl otherl. nBut if we could take a view of
tlhets orbits f tom (a distant position Ollt Of their planes, tllhey
woult appear as wso t very unequal circles, ole(c having a dlianteter t00) times greater than tlhe othter, and the small circle
movinli arounld with: its center upon tlte circumference of thle
lar ge olc, onice in a year.
* i'Franctur, Uranlog., p. 91.