The Princeton union. [volume] (Princeton, Minn.) 1876-1976, 1879-10-08
WHAT IS THE MOONS sHApEq

Is it an Ellipsoid, Egg Shaped, or Round Like
a BaIlp
From the Rochester Democrat
The moon, perhaps, presents greater
number OF perplexing problems than any
other member of the solar system. Al
though nearer to the earth than any other
OF the celestial bodies, but very lit tie is
actually known concerning our satellite
The whole theory of the moon, so labori-
ously worked out, years ago, is found to
to be at fault, and Hansen's tables are un-
reliable. There is deviation in the
moons mean motion that cannot be &C.
counted for.
The phenomena OF the moons surface
have been carefully studied for years; but
the causes of the remarkable physical
contormations can be but dimly conjec-
tured. The moons true form is the most
difficult problem Of all. The moon al
ways presents one face to the earth; but
even this fact Is puzzle. It is explain
ed that the moons axis points toward the
center Of the earth, and the moon makes
a single rotation during revolution
about the earth, thus always presenting
one slOe OF the earth.
The plane of the moons orbit is contln.
ually shifting, but this shifting does not
change to any extent the relative position
of the moon to the earth. The earth has
grasp upon her satellite that will not
permit any shifting of position, except
swinging motion Of the mass nearest the
earth, like that Of d pendulum. It has
been abundantly shown by Newton that
If the moon were sphere the earth could
have no such grasp. The conclusion is
inevitable that the moon is not sphere.
The exact shape is still question of
doubt. Lagrange insists that it is an ell
ipsoid, with the longer axis pointing to
the center of the earth. The extent of
the elongation is question yet to be set
tied. Prof. Richard A. Proctor in his
| work on the moon says: "However. it
need hardly be said that no instrumental
means at present in our possession could
show the ellipticity Of the lunar disc.''
| Notwithstanding the assumption of Prof.
Proctor, we believe that it can be demon
strated that the moon more nearly resem-
bles an egg than it does ball. Ruther-
fords stereosooplc photographs demons
bear out the theory. Photography will
probably be the only means of demons
tration, and this will he doubted by
those who believe the revelations of the
stereoscope are an optical illusion.
Rutherfords stereoscoplc views plainly
show that the moon is shaped like an egg:
with the small end towards the earth. In
the stereoscope the extreme point, or To-
cality nearest the earth, is pot far from
the great crater of Copernicus. From
this high point the surface does not re-
treat as in a sphere. There is rounding
away to a certain point, and then the
| straight. The planet is so tilted by lib
Grafton that the observer can see the true
perspective and torshortening of objects
on the surface. The phenomenon could
be observed in a telescope of large aper-
tu1e with power of fifty diameters.
The slow rotation of the moon and its
recent plastic condition explain its shape
The moon revolves on her axis in the
! same time that she revolves about the
earth, or in 80 days, 10 hours and A
minutes nearly. This motion is exceed
ing slow-so slow that even at the
equator the centrifugal force is
very slight. In bodies like Jupiter,
which revolve with great rapidity
the equatorial regions bulge out by
centrifugal force, while there is a con-
traction at the poles. In the moon this
action is reversed. When the moon was
molten the centrifcal force at the equator
was so slight that there was no bull ging,
but the earth's attraction drew out the
mass, lengthening it in the direction Of
the polar axis, and keeping the axis for
ever directed toward the earth's center.
Rutherford has waited and watched for
opportu mites to photograph the moon in
such positions as would give the sterees-
xoplc effect. LIBERATION changed the
moons face sufficiently to give this effect,
as will be observed by consulting the
photographs. Of the views of the first
quarter, one was obtained March 6, 1855.
He then waited six years for libration and
a suitable opportunity to get another view
that would give the proper effect. Be-
tween the two views of the last quarter
there is an interval of nearly SIX months.