Oxford Democrat. [volume] (Paris, Me.) 1833-1933, 1897-03-09
THE ASTRONOMICAL FUTURE or THE
EARTH AND THE MOON.

The ASTRONOMICAL tuJuHe W TIE
EARTH AND THE MOON.
Perhaps tho most interesting accom-
plishmefits Of mathematical astronomy
lrom mundane standpoint, at any rate
Arc those that refer 70 the earth's own
satellite. That seemingly staid body was
long ago discovered to have propensity
to gain little on the earth, appearing
at eclipses IN inflnlteslmal moment
ahead Of time. Astronomers were sorely
puzzled By this act Of characterization
but at last IAplace and Lagrange explain
ed Il a due to IN oscillat0ry change In
the earths orbit, thus fully exonersting
the moon, and seeming to demonstrate
the absolute stability and permanence OF
our planetary system, which the moons
misbehavior had appeared to threaten.
This highly satisfactory conclusion
Was an orthodox belief Of celestial me
chanics until 1853, when Professor Adams
Of Neptunian fame, with whom complex
analyses were . pastime, reviewed La
places calculation, and discovered an
error which, when corrected, left about
half the moons acceleration unaccount-
ed for. This was . momentous discrep-
ancy. which at first no one could ex-
plain. But presently Professor Helm
h0ltE, the great German physicist, sug-
gested that key might be found 10 tidal
| friction, which, acting as perpetual
brake on the earth's rotation, and affect
Ing not merely the waters but the entire
substance Of our planet, must In the long
sweep Of time have changed Its rate OF
rotation. Thus the seeming acceleration
OF the moon might be accounted for as
actual retardation OF the earth's rotation
"a lengthening Of the day instead OF
shortening Of the month.
Again the earth was shown to be at
fault, but this time the moon could not
be exonerated, while the estimated sta
bility Of our system, instead OF being re.
estalli he'd, was quite upset. For the
tidal retardation Is not an oscillatory
change which will presently correct IL
self, like the orbital wobble, but q per-
petual change, acting always In one
direction. Unless fully counteracted By
some opposing reaction, therefore Gas II
seems not to be-, the effect must be cumu'
lative, the ultimate consequences disas'
trous. The exact character OF these con-
sequences was first estimated by Prof.
G. Ii. Darwin, In 1879. He showed that
tidal friction In retsrding the earth must
also push the moon out from the parent
planet on a spiral orbit. Plsinly, then
the moon must formerly have been near
er the earth than at present. AT some
| very remote period II must have actual
ly touched the earth; must, In Other
words, have been thrown of from the
then plastic mass Of the earth, asa polyT
buds out from its parent polyp. At that
time the earth was spinning about In
day OF from two to four hours.
Now the day has been heightened tc
twenty -four hours, and the moon has
been thrust out to distance OF quarter
million miles; but the end is not yet
The same progress OF events must con
tiuue, till. at some remote period In Tho
future, the day has come TO equal thu
month, lunar tidal action has ceased, and
one face Of the earth looks out always al
the moon, with that same fixed stare
which even now the moon has beer
brought to assume toward her parent
orb. should we choose TO take ever
greater liberties with the future, II may
be made to appear Though some astrono
mers dissent from this prediction) that
as solar tidal action still continues, thu
day must finally exceed the month, ant
lengthen out little by little toward coin
cidence with the year; and that the moor
meantime must pause In Its outward
flight, and come swinging back on ,
descending spiral, until fiusliy, after th'
lapse OF untold eons, II ploughs ant
ricochets along the surface OF the earth
and plunges to catastrophe destruc
ton.
But even though Imagination pause
far short Of this direful elimination, !
still is clear that modern calculations
based on memorable tidal friction, suiilc'
TO revolutionixe the views formerly cur
rent as to the stability Of the plsnetarl
system. The eighteenth-century mathe
matician looked upon this system rs |
vast celestial machine which had been II
existence about six thousand years, ant
which was destined to run on forever
The analyst Of to-day computes both tn
past and the future Of this system IL
millions instead OF thousands OF years
vet feels well assured that the solar sys
TEN offers no contradiction to those law
OF growth and decay which seem every
where TO represent the immutable orde
OF pature.-From "The Astronomer
Progress Of the Century," In Harper
MaOs yine