South Bend news-times. (South Bend, Ind.) 1913-1938, 1916-12-29
If an Anship Went
By Moon it Would
Become a Planet
BY Garrett p. scrviss.

Il
does its attraction give way to the
/ greater attraction Of the sun? .. if
an airship could sail out in space
until the attraction Of the earth left
it free. would it leave the earths
orbit? 3. out in space. say a thou
sand miles from the earth, would
the suns rays be unbroken by any
/ object causing darkness, or would
there be one golden depth of light?
b. l.. r.
object in space would equal the at
traction Of the earth on the same
object when IL was about 161 goo
miles from the earths center. or
| $1,000 miles from the earths sur
face. You can make the calculation
in this way: We know that the
suns mass is about 1872. 900 times as
great as the earths, which means
that the suns attractive force is in
that proportion superior to the
earth's, so that if the object were
half way between the sun and the
earth the pull of the sun upon it
would be $4,000 times stronger
than the earth's pull.
Would Have TO Go Small Distance.
But, we also know that the force
e attraction varies with increase or
decrease of the distance, and that
this variation is in an inverse ratio
q . - e ~
if the object were brought twice as
near the earth the force OF the
earths attraction upon it would be-
come four times as great, four be-
ing the square of two. The earths
inherent attractive capacity. which
depends solely on its mass, OF guam
tity of matter, would remain the
same, but the force of the attrac-
ton, OF of the pull, would be in
creased because Of the decrease Of
distance.
At the same time the suns pull
would be diminished according 10
the same law. and would become in
the case supposed only 4-9 Of what
it was before. Dividing by 40 we
get 9, which shows that, measured
by the effect OF distance alone. the
earth's attraction on the object has
become nine times the suns.
sun Has Twice As Much Pull.
But. owing To its vast mass. the
sun still has the advantage. in to-
tai attraction. in the ratio of 3S2.-
900 TO 81. e.. the sun still pulls the /
object about $1,000 times as strong
ly as the earth pulls il. In order To 7,
have an equality we must bring the 4
object so near the earth that the 7.
gain OF the latter through decrease 4
Of distance exactly counter balances /
the suns advantage in mass. and /
this Will be effected when the dis I
lance of the object from the earth I
is represented 10y a fraction COZ the /
suns distance from the EARTH I
whose denominator is the square 1
root Of $4,000 That root is about I
81. and $4,000. 600 miles (the sun $ /
distance) divided by 90 gives about /
161, 600 miles.
This result Will probably surprise 1
you when YOU remember that the |
moon is nearly 100000 miles from F.
the earth. or half as much farther /
away than the point where the suns
and the earth's attractions should I
balance. In fact. if you make a
similar calculation to the above
concerning the attraction of the sun
and the earth on the moon YOU will
find that the sun pulls urou the
moon more than twice as powerfully
than the earth does
Why. then, does not the moon tly
away from the earth? Because the
sun draws the earth at the same
time that it draws the moon. and
the excess of its pull upon the moon
over its pun upon the earth is less
than the earth's pun upon the moon
The consequence is that the earth
keeps the moon near it. although
the real master Of the moon. as of
the earth. is the sun In order that
the earth's attraction upon the
moon should be less than the eX-
! cess of the suns attraction upon the
moon over its attraction upon the
/ earth. the moon would have 10 be
from $4,000 TO $4,000 miles from
! the earth This distance varies with
/ the position of the moon i'm its orbit
about the earth.
Blazing sun Would Stand out.
What is said above virtually an
swers your second question. Your
/ 'airship," which would have no air
out there, would cease to be a little
moon 10 the earth when its distance
] cOrresponded with that at which the
} excess of the suns attraction upon
| il over the suns simultaneous at
. traction upon the earth became
greater than the earth's attraction.
This distance would be the same as
for the moon. Beyond that distance
the "airship" would become a min
ute planet revolving around the sun.
AS TO the suns light out in space
beyond the limits Of the ear;h's at
mOsphere. you have an entirely
wrong idea in suppO~ing that there
would be "one golden depth OF
light on the contrary. there
would be no diffused light. or no
such appearance as that which we
ordinarily call daylight
II you looked directly at the sun
you would see il as a binding ball,
but the sky would De black all
around il. and the stars would be