River Falls journal. [volume] (River Falls, Pierce County, Wis.) 1872-2019, 1902-10-16
WHITE PATCHES ON THE MOON
Thought by an American Observer
to Be Snow, But English Scien-
fist Says Not.

From a series of photographs taken
in Jamaica few months ago, Prof. W..
H. Pickering has concluded that a
small amount of snow may exist on the
moons surface. He noticed in particu-
lar that the great walled plain of Plato
shows a regular progressive change
during the lunar day. White patches
are seen upon it's floor, which, as the
sun rises higher above it, diminish in
size and vanish; and these, Mr.. Pick
ering believes to be snow. In an article
entitled: Changes on the Moon-Real
and Apparent" in the Pail Mall Maya
zine, Mr.. E. Walter Maunder states his
reasons for believing that Mr.. Picker
ing is mistaken, reports the st. Louis
Republic.
The observation itself may be ac-
cepted. Indeed, there is nothing novel
about it, Such changes in the illumina-
ton of the floor of Plato are described
in all the textbooks, and, so far as his
observations have yet come to hand,
they appear to contain nothing new.
For to have snow we must have an
appreciabl atmosphere, capable of
sustaining water vapor; and that the
moon has no such atmosphere we
know, both from observation and from
theory. The sharpness with which
star disappears when the moon passes
before it, the intense blackness of all
shadows on the lunar surface, the
crispness of the horns of the crescent
moon, the absolute lack of any spec
troscopic evidence for a lunar atmos-
phere during an eclipse of the sun
an observation which was repeated I'M
der the most favorable circumstances
by the French astronomers in Egypt
during the eclipse of November II last
are quite sufficient to rule an appre-
ciable lunar atmosphere out of
court.
But the theoretical consideration
are vet more conclusive. The hrst
point to note is that lunar atmos-
phere, if it existed, would be distribut-
ed in quite different fashion from the
atmosphere of the earth. Here we
find that if we climb mountain some
three and a half miles high-a little
higher than Mont Blanc, that is to say
we should have passed through one
half of the atmosphere; the barometer
would record for us pressure but one
half what it had done at sea level.
Were is possible to ascend to twice that
height, to seven miles, the pressure
would be reduced to cne-fourth; and at
ten and a half miles, to one-elghth.
Not so with the moons atmosphere.
Whatever it's density on the surface
we should have to ascend nearly 20
miles before that density was reduced
to one-half, and to At miles before it
was CHARTERED. This difference of
distribution, if we take account of 1T
atone, would have very striking eff
feet. For, if the atmosphere density
at the moons surface were no greater
than that at 40 miles above the earth's
surface, at so miles above the two plan
cts the moon would have the denser at
mcsphere, and for all heights above
that. The total amount of such lunar
atmosphere would nearly correspond
to that above distance of 80 miles
from the earth, though it's distribution
would be very different for its density
would be much more nearly uniform.
Such an atmosphere could not fail to
give evidence of its presence in twl-
light effects, and in softening the ex-
IRENE hardness and blackness of lunar