Belding banner. (Belding, Mich.) 1889-1918, 1915-05-12
EhPERATURE OF
OTHER WORLDS IS
INTERESTING STUDY
RECENT CALCULATIONS RELIT-
ING TO TIE STNTE OF THINGS
IN MARS AND VENUS

a calculation which throws very
Illuminating side light upon the prob
lem OF the habitability of the other
planets has recently been made by
Professor j. II. Poynting. in England
II is evident, at a glance, that one OF
the first requirements which must he
met by any world, i'm order that il
may nourish inhabitants having physi
cal characteristics resem bling those Of
the inhabitants of the earth. is a SUI
ticicnt, but not too great supply Of
heat from the sun. our experience
shows that very delicate balance
must be preserved in this respect The
limits Of temperature between which
life is possible to US are narrow The
aver age temperature of the earth's
surface derived from the heat OF the
of the sun, is about sixty degrees
above above zero, Fahrenheit. If IT
were one hundred degrees above, or
ten degrees below zero. the globe
would be practically uninhabitable for
beings organized as we are. while
there are many contemporary forms
Of life on the earth which could not
endure even so slight an alteration as
that.
evidently. then, one OF the first
problems to be solved in discussing
the question: of the habitability. say.
of such a planet as Mars, is that of
its average temperature. This is not
so easy as it may seem at first glance.
Everybody learned, i'm his school days,
that the light and heat of the sun
vary in proportion to the distance. If
we know how intense its radiation is at
any one distance. then we can tell at
once how intense il is at any other
given distance. The law. i'm brief is
that the radiant energy of the sun
varies inversely as the square Of the
distance. This is easily illustrated
thus:-
Suppose a planet is situated twice
as far from the sun as the earth is;
then, according To our rule. the radia-
ton it receives will be. TO that receiv-
ed by the earth, as one to the square
of two which is four. In other words
the heat received from the sun at the
distance of the supposed planet would
be one quarter as great as at the dis
lance OF the earth. IL, on the other
hand. we suppose the planet TO be
twice as near the sun as the earth is,
then the heat ii receives Will be four
times as great as that received by the
earth.
Now, this law has sometimes been
thought 20 give true representation
OF the temperatures prevailing on the
various planets. but 1t does not do SO,
and the fact that IL does not is OF
great Importance when we come to
consider the habitability OF other
worlds What we need 60 know. in
discussing that problem, Is the actual
temperature TO which the surface Of
the planet is raised BY the heat from
the sun falling upon H. and il has
been found that this temperature var
les not inverseiy as the square. but in
yersely as the square root OF the dis
I lance This makes very great diff
( ference i'm the results. and a difference
which, as far as it goes. favors the
( Availability of certain planets which,
/ judged by the law OF inverse squares.
would have TO be incontinentiy thrown
out Of the list.
/ For instance. take again a planet
twice as far from the sun as the
earth Is. IL receives only one quarter
as much heat as the earth gets, but its
surface temperature will be to that of
the earth as I TO 1.42 because the
square root of two Is represented by
/ the deciaml 1.42 very nearly. IL