Evening star. [volume] (Washington, D.C.) 1854-1972, 1931-01-25

transmitted to the earth per unit area. Ti1S
most uncertain part Of this calculation occurs
In the correction which must be made Tor losses
when the rays are passing through the eartnS
atmosphere. Atmospheric conditions on the
planets differ so measurably from those on
earth that the temperatures obtained by placs
ing a thermometer near their surfaces would
probably differ greatly from the results obtained
by the radiation methods described In this
article
The maximum temperature recorded on Mers
curry is about 800 degrees Fahrenheit the dis
tribution of radiation over its surface being
quite similar to that of the moon. The tenn
peratures on Mars are somewhat like those on
cath, but vary greatly with the season ana
the hour of the day. The outer planets, unless
they give OF heat from their interiors, are very
cold because of their remoteness from the SUM
Jupi;ar has long been supposed to be warm
but the recent thermocouple observations snow
that its temperature Is approximately minus
216 degrees Fahrenheit. The nocturnal tens
perature in the atmosphere OF cloud-covere0
Venus is about minus degrees Fahrenheit.
DRS. PETIT AND NICHOLSON reports
after seven years of stellar observations
that the temperature at the point on the moon
where the sun is directly overhead Is aboue
244 degrees Fahrenheit at the time OF fun
moon and 149 degrees Fahrenheit during the
first and third quarters. This variation ap-
parently is caused by the irregularities In the
moons surface which tend to increase radia@
ton sent out in the direction Of the lunar
zenith and decreases that emitted toward the
horizon. The true temperature Of the moon Hes
somewhere between the figures mentioned
above.
Science appreciates that much more is to b
learned about both the planets and the mooD
from the invaluable Carnegie Institution re-
search The cooling and heating Of the moon
Is governed by the amounts of sunlight which
are flooded upon it. The Investigators hope to
discover eventually what kind Of rocks occur
in the surface of the distant moon. In fact
laboratory tests have already been made with
granite, lava, quartz sand and various other
materials by heating and cooling them observ=
ing the rates at which their temperatures
change, in order to compare these results with
those obtained from scientific observations with
the thermocouple of the moon itself.
The variation in the radiation and tempera-
ture over the sun-lit side of the full moon was
obtained by allowing its image to drift ACROSS
the receiver of the thermocouple while q
moving Photographic plate traced the defec-
lions of the galvanometer which resulted. The
planetary heat varies from a practically un~
measurable quantity at the edge to a maximum
at the center. Observations Of lunar eclipse
several years ago showed that the temperature
at the observed point fell a total of 335 degrees
Fahrenheit during the eclipse the greater part
of this drop occurring during the partial phase
of that particular eclipse. This record is in
marked contrast to the observations of solar
eclipses on the earth, which featured falls in
temperature of only 4 to degrees Fahrenheit
The mountains in the moon-yes, there il o.
lot yet 10 be learned about them, but that il
just another story.