Juniata sentinel and Republican. [volume] (Mifflintown, Juniata County, Pa.) 1873-1955, 1877-08-01
Changes In the Moon.

Although the moon may be regarded
as to all intents and purposes dead, it
must not be supposed that no changes
whatever take place upon her surface.
On the contrary, some of the peculiari-
ties of the moons condition must tend
to cause even more rapid changes of
certain orders than take place in the
case of our earth. Thus the great
length of the lunar day, and the moons
waterless condition and rare atmos-
phere, must help to cause a compare
lively rapid crumbliDg of the moons
surface. During the long and Intensely
hot lunar day the rock substance of the
moons surface must expand consider
ably, for Ii is raised to a degree of heat
exceeding that of boiling water. During
the long lunar night the surface is ex-
posed TO degree of refrigeration far
exceeding that of the bitterest winter
in the arctic regions, and must contract
correspondingly. This alternate ex-
pansion and contraction must gradually
crumble away all the loftiest and steep
est portions of the moons surface and
will doubtless, in the long run-that is,
some few hundreds of millions of years
hence-destroy all the most marked ir-
regularities of the moons surface. The
causes of change which have been
recognized by telescopists who have
carefully studied the moons surface
may all, without exception, be referred
to this process of gradual, but steady,
disintegration.
The most remarkable case hitherto
known, for example, the disappearance
of the lunar crater Lime, is far better
explained IN this way than as the result
of volcanic outburst. This case has re-
Gently been described as follows by the
present writer: In the lunar sea of se-
renity there was once a deep crater,
nearly seven miles across, very dis
tinct and obvious feature, even with
the small telescope Qess than four
inches in aperture) used by Beer and
Madler in forming their celebrated
chart. But, ten years ago, the astron- |
omer Schmidt, selenographer of selen-
ographers (whO has, in fact, given the |
best energies of his life to moon-gaz-
ing), found this crater missing. When |
he announced the fact to the scientific |
world, other astronomers, with very /
powerful instruments, looked for the |
crater which had been so clearly seen |
with Madler's small telescope; but
though they found crater, il was
nothing like the crater described by
Nader. The present crater is scarcely |
two miles in diameter and only just
visible with powerful telescopes. All
around il there is shallow depression,
occupying a region about as large as
the whole crater had been before. Ii
seems impossible to doubt that a great
change has taken place here, and the
question arises whether the change has
been produced by volcanic activity or
otherwise. Sir John Herschel pro-
nounced somewhat confidently in favor
of the former hypothesis. "The most
plausible conjecture" said he, "as to
viz NHuSS VI ihiS uiSdiptdIduSc stculs
10 be the filling up of the crater from
beneath, by an effusion of viscous lava,
which, overlooking the rim on all sides,
may have so flowed down the outer
slope as to efiace its ruggedness, and
convert it into a gradual declivity cast
ing no stray shadows. "But how tre-
mendous the volcanic energy" we note
in the passage referred 10, required to
fill with lava a crater nearly seven
miles in diameter, and more than half
a mile deep. The volcanic hypothesis
seems on this account utterly incredi-
bic, for if such energy resided in the
moons interior We should find her
whole surface continually changing.
Far more probable seems the idea that
the wall of this crater has simply fallen
In. scattering its fragments over what
had once been the floor of the crater.
The forces at work in the moon are
quite competent to throw down steep
crater walls like those which seem
formerly TO have girt about this deep
cavity. ."-C0rnhW Magazine.