Evening star. [volume] (Washington, D.C.) 1854-1972, 1900-03-19
MYSTERIES OF THE MOON.
Interesting observations by Prof.
Pickering of Harvard University.

Interesting observations by Prof.
Pickering of Harvard University.
From the Boston Journal.
In q broad, fiat expanse on the moons
northern hemisphere. known to astrono-
| mers as the Mare Serenitatis there is a
whitish spot, some four or five miles in
| diameter, to which the name of Lime
has been given. 1t has been assiduously
watched for many years. because about
1866 something occurred which caused a
| wonderful change in its appearance. Before
| it looked like crater, but little elevated
! above the plain and its throat filled with
black shadow. Suddenly, instead Of a
crater. 1t appeared as a white spot Later
| on dark center showed in the spot as If
| the missing crater had yawned again be-
meath its mysterious covering. But no fur
| Their change occurred, and as more than
| thirty years have since passed without any
alteration in the aspect of Lime, some
| astronomers have begun to question wheth-
er the observers Of a quarter Of a century
ago did not make mistake.
Now Prof Pickering rescues LINES rep
| utation genuine marvel. but at the
same time increases the mystery. Watch
| ing II during the eclipse. when the shadow
Of the earth passed like a cooling cloud
across the face Of the moon, he found by
| careful measurements that the size Of the
white spot surrounding Lime increased
while buried in the shadow. the amount of
the expansion in the diameter of the spot
being about one-slxth Of mile. As the
eclipse passed on it began to contract again.
But this Is not all. Measurements Of the
enigmatical spot made when there was no
eclipse showed that 1t undergoes a similar
but much more extensive fiuctuation in con-
sequence Of the variation in the intensity of
the sunlight falling upon it in the course of
the lunar day. day upon the moon Is
equal to about fourteen Of our days-that is
to say. nearly two weeks elapss 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 1t diameter Of nearly five miles.
Measured after 1t has been exposed eight
days to the uncTouded sun. Its diameter is
less than two miles and q half. During the
long lunar afternoon. as the sun gradually
sinks and the fierceness of its heat becomes
a little tempered, Lime begins to increase
again in diameter. and when the sun gets
near the horizon the wonderful spot is seen
to have almost regained the magnitude that
it had just after emerging from the lunar
night.
These changes suggest frost spreading in
the shadow and receding in the sunshine.
or a cloud alternately growing and con-
tracing 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 1t to expand to a
measurable degree shows how sensitive 1t
Is to alterations of temperature
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 motions
and changes visible to our eyes, their pres
ence may possibly Indicate the existence Of
yet more interesting things In the lunar
world.
1t should be added-because the fact while
a. present Increasing the mystery, may In
the end aid In solving it-that changes like
those witnessed In Ldnne do not appear to