The Columbus dispatch. (Columbus, Miss.) 19??-1922, 1922-02-05
Irregularities Of
The Dear Old Moon

Several newspaper articles have
been published in regard to an ac-
celebration or reduction Of the moons
velocity in its revolutions round the
earth, and the subject has been treat.
ed by these photographers as if it
were a new irregularity Of our satel-
lite, at the same time intimating that
the solar system may be out of joint.
Now the moon moves in its orbit
in accordance with certain inhexible
laws, obedient to two forces-the cen.
trifugal force which impels it to fly
off into space in a straight line, and
the centripetal force-due to the
earth's powerful attraction -whic
tends to draw it to the earth's sur.
face. At an average distance of
about 100000 miles (for the moon
moves in an elliptical orbit round its
primary0 these two forces balance,
hence it moves in close orbit around
the earth.
But the moons orbit, like the earth's .
is subject to perturbations caused by I
the attraction of other planets as they
pass by the earth, or as the earth
passes by them while they are moving
in their respective orbits. When, for
instance, the earth passes by the gian'
planet Jupiter, or by the smaller,
nearer planet Mars, the attraction of
either p!aEet tends to draw the earth
towards the planets, which results in
pulling the earth Slightly out of its
normal course, which would otherwise
be true curve with the sun as the
,enter. The deviation thus produced
IS called perturbation Of the earths
orbit.
Now the same force that would per-
urb the earth, either by Mars, Jupi-
er, or by Venus on the other side,
would have the same effect in modify !,
ng the course of the moon n its or
ut round the earth as a center But
he moon accompanies the earth in its
notion round the sun, but is constant
Y varying in its distance from the :,
I'm, for it is sometimes above or out =
ide the earth's orbit, and sometimes ;
Glow or within it, and is therefore =
ubject to still more complex pertur =
ations than the earth itself. !
But there is still further complica-
ions of the motions of both the earth
nd the moon in their respective orbits
nd that is the accelerating, or re- =
arding effect of both these bodies in !,
leir orbits as they approach one or !;
mother of the other planets, or get =,
eyond that influence as they pass Il
Y it. q
Thus it will be perceived that very N
implicated calculations, based on D
ng series of precise observations, r,
re involved in predicting with abso to
tie accuracy the future effect Of t.
ese perturbations. And in fact they V,
e still further complicated by an
her consideration; the positions of be
e other planets are never the same 81
any two successive datess hence NJ
e calculations become so abstruse, Sc
fined, and difficult, that it has
therto been impossible to fix the ex :
t position of the moon within aIiI
W seconds of arc for future dates.
1t the discrepancy is small, humanity III
eaking, only a few seconds per /
1nth and very few minutes per
mum.
These unexplained deviatiors Of the
'on from its predicted position arc
He'd "The Problem of the Lunar
cory" and it is as old as precision
astronomical observations has been
lcticed, dating back more than
ltury. The time may come when
ne patient mathematical genius
i be equal to the task Of solving
, problem.