San Antonio daily light. [volume] (San Antonio, Tex.) 1886-1907, 1891-03-28
THE MOONS TEMPERATURES.
Not Much Below 1909 +. in This
Writer'S Opinion.

NOT muCn Below lOOS II. III LIE
Writer'S Opinion.
From the English Mechanic.
Mr.. Pearl is under the impression
that have omitted to take INTO ac'
| count the question of the temperature
of the moon. 1t is true that uiu hoI
consider it requisite to raise discus
sion on that question, but had sat
isfied myself, by collecting all the
evidence obtainable, that the temper
ture of the moon was considerably
above the freezing point, and L made
INV caIcutions for that point accord
inSIv. In doing so, L considered
that I was giving rather than receiv-
ing an advantage.
will now state my reasons for re-
iecting all the extravagent assump-
tions of the existence of an excessive
Iy low temperature on the moon, as
the extreme estimates of the temper
allure of space. l think that we have
evidence to show from our own ex-
perience of the long night in our own
polar regions VERY much longer than
the lunar night that the temperature
of space can not be lower than 1909
below Fahrenheit's zero, or about
7So G.. below the freezing point. The
lowest recorded temperature of the
polar regions can not be many de-
grees above the temperature of space,
or above that of the coolest region of
the moon, because the effect of an at
mosphere IL merely to retard or delay
radiation by few days or hours,
not to prevent it altogether.
Mr.. Peal arrives at his estimate of a
possible lunar temperature of 5000
below zero by a process that is alto
gether inadmissible. He assumes
that the radiation from the mon is
excessively great, and that the heat
ing power of the sun is excessively
small. This is an impossibility, the
two conditions being irreconcilable.
We know from our terrestrial expert
ence that good radiators of heat are
good absor bers of heat, and that bad
absorbers are bad radiators. Mr.. Peal
may take his choice of the ways OF
looking at this matter; but he can not
be allowed to take half of the one and
half of the other to make good his
theory. II the want of an atmOspher-
ic jacket promotes radiation, it must
also promote absorption, and If the
dark side of the moon is excessively
cold, the Illuminated side must be
excessively hot; or conversely, If the
SUMS rays do not bring the moons
surface to high temperature, the ra-
diation cannot lower it much. 1t
does not matter what his choice may
be; in either case the conclusion
must be against his assumption.
A provisional estimate OF the tenn
perature of the moon may be arrived
at by taking a mean of the actual OBJ
which range from 32o to
500 > say 1860 for the illuminated
region of the moon, and as.
that the temperature eff the
dark side falls as low as 1907 below
zero. This gives an average Of $50,
which, strange to say, is about the
same as the average temperature of
the earth's equator. The tempera-
ture of the lunar poles may alse be
taken as about the same as that
of our own polar regions. There is no
reason why this estimate should not
be accepted as approximately correct.
The real influence of an atmosphere
is to retard for q time the nantes
tation of extremes or temperature,
whether hot or cold-not to increase
the average. The mean temperature
Of the moon should, therefore, be
abouth the same as that of the earth.