South Bend news-times. (South Bend, Ind.) 1913-1938, 1921-11-30
MOON TO HIT Us?
Able SAYS "BOSH"
Director of BOurges Obser.
vator Advances Theory to
Discredit idea
BY ABBE TIL. MOREUX.
Director Of the Observatory of
BOurgcs.
written for the International News
Service and Petit JournaIN

! (WrittCn for the International News
Service and Petit JournaI)
PARIS, Nov. "a recent state
ment by the English astronomer
Crommelin seems 20 have caused
| considerable emotion I'm the public
mind. The last eclipse of the moon,
/ he believes, proves some Of our theo-
ries false. Our satellite, he says. is
disObeying the universal laws OF
gravitation. and if the phenomenon
continues we shall be condemned
some day 10 have the moon fall on
our heads.
The fears inspired by such pro-
nouncement have caused many Of
my friends 10 write and demand my
views.
In the first place I must reassure
them. The problem is not new, be-
cause ii was raised very clearly by
HALEY Cthe discoverer Of HalIey's
comeD in 1893. At that time as
tronomy showed that the moon pos
/ sessed a movement quite different
/ from that OF other celestial bodies in
/ the sense that its movement was not
uniform but accelerated. That was
/ learned by examining ancient
eclipses. In 1000 years the moon
| seemer 10 have advanced in space
/ by about two times its diameter, that
/ is to say. that IL was far from occu-
plying the position assigned 10 il by
/ the law formulated by Newton
Law OF Mechanics.
At first it seemed simple enough
that the acceleratiOn would continue
1 To- 1Trr
would fail upon the earth. But such
a problem tempted the genius of
Laplace, and that skilled mathema-
tician proved in 1877 that the phe-
nomenon explained itself easily by
the laws of celestial mechanics.
We know that the earth describes
around the sun in the course of a
/ year. not a circle. but an eliipse.
Laplace demonstrated that this
does not always have the same
I form. We can compare il TO a hoop
upon which one exercises a lateral
pressure, and which. in consequence.
is flattened little.
At present this ellipse becomes
year by year more circular and in
| $4,000 years il will be really cir
Cular. After that IL Will tend 10 be-
come ei.iptical again for more than
/ 10000 years.
solution offered.
Now. since the moon turns around
I the earth, at the same time being
susceptible 10 the influence Of the
sun. one can readily conceive that
every change in the distance of our
globe from the sun would have its
effect upon the position Of the
moon. In other words, according TO
whether we are nearer or farther
\ from the sun, our attraction on the
moon increases or decreases. and
| consequently the moon must in
/ crease or diminish its speed of
/ movement.
At present. and since a long time.
\ the moon has been increasing its av-
/ erage speed The increase, however,
/ IS insignificant. for in 100 years the
moon has hardly advanced in its
/ trajectory more than 10 miles
All this we must admit. is theoret-
4 zeal and by no means absolutely eX-
act. When we have greatly improv-
/ ed our tables on the moon and its
various positions. we shall still be
J incapable of predicting for "a Ions
time IN advance what place the
moon will occupy in the heavens.
\ The errors viii be very small but
/ they exist, and proof is the fact that
\ at each eclipse OF the sun we notice
some small error OF some seconds in
I the time calculated and the time ac-
\ tually observed.