New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1877-08-24

FAVOnAB1F POSITION or MAEs FOR OBSERVATIONS
THE SMALLEST KNOWN CELESTIAL BoDlr>-
VALUE OF TIE DISCOVERY TO ASTRONOMICAL
SCIENCE.
TO the EditOr Of The Trtbun0
SIR: Some particulars respecting the newy-dis-
covered satellites Of Mars may not be unntcresting
TO the readers of TnE TRIBUNE. The first question
winch will naturally arise is why have these objects
not been seen bcfUe7 The answer is that Mars is
now nearer to the earth than it has been at any
time since 1919 when the great telescopes Of tine
present had hardly begin TO be known. The next
opportunity for seeing them occurred in ] $50. Dut
we may suppose they were then not especially
sought for with the two OF three telescopes which
alone would show thom. The next favorable ovpo-
sition was in 1S-@. but Mars was then so
far south OF the equator that il could not
we'll be observed in or laitudes The present or
position is about the best possible 10. ob-er-
walton in the middle atiuAes of our hemisphere,
because toc worry small deviation from greatest
possible approach 10 the earth arises fcon the oplO-
sition occurring few days after thc planet reaches
It's position, and this throws it farther north in de
cinaiiou han It would be at tie time Of absolutely
nearest approach. The next opposition viii occur
in October. 1879, and there is some hope that thc
satellites nay THEN again bee observed wl'h the ASH
ingtm telescope. Daring tho TEA years following
telescopes Of the world because, owing 20 The great
eccent1city Of the orbit Of Mars thc planet viii be
zoo far away at the Times Of opposition In 1902
favorable opposition viii again occur. During the
present year il Is hardly likely that lie satellites
will be visible after October.
OF the two satellites n1w discovered The most tx
traoIdpary lecture the proximity q Che inner oac
90 zoe planet. and Ire rapidity Of lis revolution.
The shortest period hitherto known is hat OF the
inner satellite Of Satwn-yveuty-two aud half
houis. But the inner satellite OF Mans goes round IN
seven hours ard Eirty-eighy Minutes, It's distance
from thc centre Of the planet is a0oui G,0J0 miles,
and from the surface less Than 1000 II there are
any astronomers on Mars with telescopes and eyes
like ours, they can readily find out whether this
satellite is inhabited the distance being less than
onc-siXtetl that OF tint moon from
That kind Of near approach to simple reia-
tionships between the times Of revolution. - found
here which we see ~ the satellites OF Jupiter and
Saturn. The inner satellite oi Mars reyolyes in
very nearly oncfourth the period Of the outer one,
these times being
Ou;cr satellite, :{gn. 14n.
Que f,irjh this peiioa, ". 33can.
Period oi inner satellite, ~. 3Sni.
These satellites may also be put down IS by far
the smallest heavenly bodies YET known. u IS
hardly possible 10 make anything Ike anumell-
cal estimate OF Their diamctcrs because they are
seen in tie telescope only flint PORTS Of light.
But one might safely agree toride round one o tnem
in railway car between two successiye meals OF to
walk round in easy stages during very briet yaca-
ton In fact surprising the surface Of the cutter one
10 have the same rejecting power with that OF Mars,
It's diameter cannot be much more than ten miles,
and NAY be less
A!to..fher these objects must be regarded
among The most remarkable Of the solar system.
Not the least service which Prof Halls discovery
wall render 20 astronomy is that OF an exact de-
termination Of the mass OF Mars, and q consequent
.inpEacahon of he theories OF the four inner
planets The NEST profound researches on this sub
iect hitherto made are those Of lie Ncrrier and Ge
may regard his mass OF Mars as the product Of
century Of observations ahd several years Of abor-
Gus circulation by a corps of computers From Prof
Halls MEASURES on four nights there Is obtained by
ten minutes computation
Mass Of the SIM