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

01i' TEII]i SUP']1RIORlt PIANJI'S —......... MAt'i1T't, PLANET'OID)S JUPITEMlT,
SATUttN,) URANNUS Ai) NiNET'UNE.
320.'Ti:, Superior planets are distinguished friom the tInferior, by being seen at all distances firom tlhe stu firom 0 to:1800. II.aving their orbits exterior to t hat of the earth, thley
of course never come between uls and the sun, that is, they
have never aly inlfelior conjunc tion lile M:ercury and r Vells,
but they are seen in sul)erior coljunction and in opposition.
Nor do they, like the inl'erior planets, exhibit to the telescope
ditff'nllt p)hases; b)itt, with a single exception, they alwa)ys
present the side that is turned toward the earth fully enlightened. Thi8s s o\Ying to their great distanllce fiom tlte earth
for were the spectator to stand iiponl the sitl, lie \would, of
coursel, always have the illulminated lside of each of the planets
tutnred towarld hlim; but so distant are all the superior plaitets except f:Mars, that they are viewed by us very nearly ias
they woulld be if we actutally stood on the sun.
321. MAilAs is a small planlet, his diameter being only aboutl
half thlat of tlte eart}h, or 4500 miles.X' life also, at times, comes
nearer to us than any other planlet except Venus. IHis meam?
distance is 14Jt9,200,000 miles; t})t in conseqitence of tte ceeelntricity of his orbit., thie distanice varies greatly, tile differenice
betNween the perihelion and al)ltelionl distances being 27,000,000
miles.:Mars is always lear the cecliptic, never varying frolml it
20. ie is (distisnitguisled from all tle other plancts by his (ldeep
red color and fiery aspect; but his blrighttecss and apiparent,
m1agitlitulde vary much at dife'rent times, being sometimes
nearer to vus thlan at others by the whole diameter of the
eartlh's orblit, thait is, by about 1.90,000,000 miles. \Whein Mars
is oil tle samet side of the stn Nwith tlhe eartlh, or at his opposition, lie comles within 50,000,000 miles of tie earth, and, rising
Ho tind.