The Seattle post-intelligencer. [volume] (Seattle, Wash. Terr. [Wash.]) 1888-1914, 1900-06-04
MYSTERIES OF THE MOON.
INTERESTING OBSERVATION By An
EMINENT ASTRONOMER.
Prof. Pickering, OF Harvard. De-
scribes the Mare serenttntis,
which Has Long Been Under Close
scrutiny.ThreshoId of Discovery.

In a broad, fat expanse on the moons
northern hemisphere, known to astrono-
mers as the Mare Serenitatis, there is a
whitish spot some four miles in diameter
to which the name Of Lime has been
given. II has been assiduously watched
for many years, because about 1856 some
thing occurred which caused a wonderful
change in its appearance Before It
looked like a crater but little elevated
above the plain and its throat filed with
black shadow. Suddenly. instead OF
crater. 1t appeared as a white spot. Later
on n dark center showed in the spot, as
IL the missing crater had yawned again
beneath its mysterious covering. But
no further change occurred, and as more
than thirty years have since passed with
out any alteration in the aspect OF Lime
some astronomers have begun TO ques-
ton whether the observers of a quarter
of a century ago did not make mistake.
Now Prof. Pickering rescues Lime
reputation as genuine marvel, but at
the same time increases the mystery.
Watching II during the eclipse. when
the shadow OF the earth passed like
cooling cloud across the face OF the moon,
he found by careful measurements that
the size OF the white spot surrounding
Limo increased while buried in the
shadow, tho amount of expansion in the
diameter of the spot being about one
sixth of a mile. AS the eclipse passed
of 1t began TO contract again
But this IL not all. Measurements OF
the enigmatical spot made when there
was no eclipse showed that IL undergoes
a similar but much more extensive fuctu-
alton In consequence Of the variation in
the intensity OF the sunlight falling upon
It In the course of the lunar day. A
day upon the moon Is equal to about
fourteen OF our days-that is to say, near
~ two weeks eIapse between sunrise and
sunset at any point on the face of the
moon Measurements of Lime made two
days after the sun has risen upon II give
It diameter of nearly FIVE miles. Meas
ured after 1t has been exposed eight days
to the unclouded sun its diameter is less
than two miles and half. During the
long lunar afternoon, as the sun gradu-
ally sinks and the fierceness of its heat
becomes little tempered. Lime begins
to increase again in diameter. and when
the sun gets near the horizon the wonder
full spot IL seen to have almost reganed
the magnitude that IT had just after
emerging from the inner lunar.
These changes suggest frost spreading
in the shadow and recedihx in the sun
shine, or cloud alternately growing and
contracting under similar influences. The
fact discovered by Prof. Pickering that
even the shadow of the earth falling for a
short time upon the spot causes It to ex-
pand 10 a measurable degree shows how
sensitive 1t Is to alterations of tempera.
ture.
But frost or a cloud upon the moon pre-
supposes an atmosphere and vapors there.
They certainly must be widely different
from such things upon the earth. but II
they are abundant enough to cause mo-
lions and changes visible to our eyes, their
presence may possibly indicate the exist
ence of yet more interesting things In the
lunar world.