New-York tribune., 1901-08-18
EXCEPTIONAL E1RTHSHINE.
AN UNUSUAL VISIBILITY OF THE NEW MOON
INVESTIGATED BY EXPERTS

INVESTIGATED BY EXPERTS.
There are two sets of conditions under which
it is possible to see light on the moon which
comes from the earth. One of these exists at
the time of total eclipse of the moon when
the earth is directly between that body and the
sun. Enough solar radiation. passing through
the ring OF atmosphere around the earth, is bent
from it's natural path TO illuminate the
family even while it is in the earth's shadow.
The moon will sometimes be dim end dUSiy
during an eclipse. and sometimes it has a fairly
bright copper color. The degree of illumination
depends upon the clearness or cloudiness of the
earth's atmosphere in the regions where the
bending occurs
The other situation is produced when the moon
gets between the earth and the sun-at the time
Of new MOON The side of the earth which is
turned toward its satellite is brightly illuminat-
ed by the sun. whereas the side of the moon
which is directed toward the earth receives no
sunlight at all little light however. is thrown
back from the earth's surface to the moon. This
phenomenon is reflection; the other one
fraction.
The amount Of reflected light is variable. as
we'll that which is refracted. What is called
"earthshne" is much brighter at one time than
another. Attention has recently been directed
To a statement made by c. F. Lumsden, presi-
dent Of the local astronomical society in To-
ronto this subject He reports that on the
evening Of March 22 when the moon was nearly
new, the dark portion distinctly visible
that several of the mOet prominent formations
seas and mountain ranges could be identified
with an opera glass. The part of the earth
which turned toward the moon at that hour
embraced Western America the Pacific Ocean
and Eastern Asia Mr.. Lumsien has asked for
information tending TO show whether or not any
.Nt a this tor
Of the globe to account for the unusual degree
of illumination.
The matter has been Investigated by the United
States Weather Bureau and il now reports that
of the area which eoncerned in producing
the earthshine about l. per cent was land and
- per cent was water Four-tenths Of this land
is covered with cloudness in March. on the
average and about foLr-tenths with snow. over
the ocean the normal percentage Of cIoudiness
for th~ months is about six-tenths. Log
books of Pacific steamships have been consulted
To II there unusual amount Of cloud
March -. The lower side Of cloud is likely
To- be dark but the top is white when in a Hood
Of sunshine. Hence il is assumed that the great
the cloudiness the more powerful would have
been the reflection. No definite evidence OF the
prevalence Of more than the ordinary amount
on the date mentioned has been secured But
granting that there was enough To- raise the pro-
portion TO ScVen-tenthS, Professor Able doubts
whether the dinererce would account fc- the
observed effect.
He suggests another explanation. however,
which clears up the mystery in a rather more
satisfactory manner. The moon at perigee is
only 22l 0O0 miles from the earth. while at apo
gee she is 2J3.tn0 miles Off OF course the
closer she comes the more strongly she will e
Illuminated by earthshine. Ii is estimated that
the brightness at the least distance would be -
per cent greater than at the greatest. This is
far greater variation than is likely to occur in
the amount Of terrestrial cloudincss and the
almanac shows that the moon had just passed
perigee at the time when Mr.. Lumsden made his
observation Still the here specified
should operate with equal power once a month.
II would seem therefore, that there must have
been a somewhat combination of astronOm-
ical and meteorological influences at work to
produce earthshine OF exceptional intensity. The
moons position in her orbit does not completely
explain the facts.
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