Richmond times-dispatch. [volume] (Richmond, Va.) 1914-current, 1919-11-16
MOON keeps SAME SIDE
TO EARTH At ALL Times
heSolvcs on Own Axis as Earth Does
and Makes Complete Revolution
Every Month.
EXPERT EXPLAINS REASON
PROFESSOR Scrviss Declares That Often
slightly More Than One Side of
Moon Can Be Seen Because Orbit
Around Earth LIS au Ellipsc.
ny GARRETT r. sEnvIss.

Docs the moon rcvolve on it's own
axis. as the earth does? WHY do we
always sec tho same side OF the moon?
What is on the other side?-J. w. S.,
Provdenco"
Yes. the moon does revolve, or ro-
tate. just as the earth does, but much
moro slowly. so that by making one
turn upon itself in one month. il keeps
the same side continually toward tic
earth.
To convince yourself that tho moon
must rotate once every time il goes
around the earth. for else il could moi
Keep the same side always toward us
walk around table or chair in the
center of room. keeping your face
and the front OF your body constantly
toward 1t: you will find that your
body makes a turn around it's own
vertical axis each time that you circle
The table. II tie moon did not turn
once around during its every rcvolu-
ton about the earth. we would sec all
SIDES Of It in succession in the course
OF d month.
Would Rotntc About Axis.
Even II the moon werc bound 70 Tho
earth by rigid attachment, such as
steel truss. or cantiievcr beam, it
would make during every revolution.
one rotation about an axis through its
center. perpendicular to the plane of
It's motion around the cart., The con-
nec'ins truss would not affect this
radtal arm projecting from the moon,
and swinging around with it, Every
particle In the moon would, with ref
crence TO surrounding space, make a
virtual rotation about the moons con-
;er each time that the moon was car
ried around the earth.
70 see that this is so. draw small
circle near tic edge of sheet of
paper. make number Of dots in the
circle. one being exactly in it's center
then attach the paper TO table by
a pin through the middle of the sheet
and revolve the sheet around the pin.
keeping your eyes on tho central dot.
you VIII perceive that the other dots
appear TO revolve around the central
one. beautiful example of relative
motion may be seen from a railroad
train. Any spot on which YOU fix your
eye becomes center of revolution for
the landscape.
Sec Around Wentern Edge.
But. as the moon Is not rigidly at
tached to the earth and as it's orbit
about the earth is an ellipse instead OF
"A circle, II does not, in strict fact. keep
turned cart:iward. When it Is in the
nearer part OF the orbit and conse-
PucHtly travelling faster. its revolution
gains upon It's rotation, so that we
edge OF the moon. and when the revo-
luton Is slower than the rotation. we
see around the eastern edge. Besides
this. YOU see sometimes little over
the. northern edge and sometimes a
little over the southern edge of tie
moon. according. as her North Pole or
her South Pole happens TO be inclined
toward the earth.
There is even third way In which
We get glimpses of the half of the
lunar globe that Is turned from the
earth. This third way depends upon
the. fact that the earth is so large
with reference 10 the moons distance
one Side OF tie earth. as when the
moon is rising. and then from the
other side, as when the moon IS set
ting, We see In the first case a little
over the western and in the second