Evening star. [volume] (Washington, D.C.) 1854-1972, 1931-01-24
PUM|CE AND ASHES
IN MOONS MAKEUP
Carnegie Institution Group
Makes Report After
Studying Orb.
BY THOMAS R. HENRY.
Lady Moon has a pale face.

Lady Moon has a pale face.
The features of earth's light-shrouded
daughter seem to be made up largely of
materials similar to pumice and vol
canic ashes on the earth, according to
q report just made by the Committee on
the Study OF Surface Features of the
Noon of the Carnegie Institution of
Washington.
This committee, headed by DR.. F. e.
Wright, Is trying to find out, over ap-
proximately 100000 miles of space, as
much as possible concerning the exact
conditions which obtain on the earths
satellite. Concerning her complexion"
they report, three distinct lines of EVIL
dence all point in the same direction.
Light Reflected From Sun.
First is the complicated phenomenon
of the polarization of light. Moonlight
is reflected sunlight. There are certain
differences between pure light received
directly from a luminous body and re-
fected light, due to the fact that part
Of the light which strikes q surface is
absorbed. This can be determined with
instruments. The measurement of this
difference tells something of the nature
Of the rejecting surface, regardless of
how far away it may be.
al OlIc CdSS VI LI1G Tile COms
mittee reports, there is very little light
that the surface materials must be light
colored, like pumice, granite or sand
stone, and not dark, like basalt or
most other heavy rocks. But granite
appears to be thrown out as a promi-
nent part of the moon surface by an
other phenomenon-the fact that
measurements taken during an eclipse
when radiation from the sun is shut
of for a brief interval show that the
moons face chills very rapidly Granite
and other massive rocks absorb lots of
heat. When heated to the boiling tenn
perature of water, the temperature of
the moons surface at noon, and then
placed in a cool place they require
long time to lose the heat they have
absorbed.
Heat Insulation Indicated.
The rapid chilling shows that the
moons surface must be composed of
excellent heat inSulators which throw
of the radiation of the sun almost
as soon as 1t strikes them. A third
line of evidence is that the distribu-
ton of planetary heat over the moons
surface generally agrees with that de-
termined experimentally for a rough
surface composed Of pumice and vol
canic ash. This planetary heat is not
reflected sunlight, but radiation emitted
by the surface Of the moon itself. A
small amount of the suns radiation is
absorbed by the surface materials which
are heated so that they send out heat
waves of their own. This radiation is
of long wave lengths and extremely low
The measurement of it,
distinct from the reflected radiation,
rAAI hxy TN~- S-A1 -
Nicholson and Edison Petit of the
Mount Wilson Observatory and is con-
Sidered an outstanding achievement.
During the year, the committee re-
ports to DR.. John G. Merriam, president
Of the Carnegie Institution, measure
mentS have been made of the relative
of light reflected by so diff
ferent rocks and other materials found
in the surface of the earth. Intensities
we're determined for different angles be- |
tween the incident and reflected rays |
and for different parts Of the spectrum. |
Similar measurements on light from the |
moon will be made with the same |
equipment and will aid in the CLASH |
dcation of lunar surface materials.
Maps Being Prepared.
Besides trying to determine the sur
face materials, the committee is pre- |
pairing what Will be the f1rSt really ac- |
curate maps of the moon, based on |
negatives taken by the 100-inch tele-
scope at Mount Wilson. These maps, |
which will serve as a basis for critical |
study and classification |
II the land forms observed on the moon, |
will be free, the committee reports, |
from the personal factor which entered |
into the construction of all previous |
maps, which were drawn by hand.
The degree of accuracy, says the
committee, depended on the skill of
the observer in determining the features
observed through the telescope and on
the quality of the telescope and photo
graphs used. On the new maps it will
be possible to read directly the latitude
and longitude of any point on the |
moon with the aid of specially pre-
pared lunar projection chart.
Another determination reported by |
the Moon Committee Is that all parts |
of the moons surface are not equally |
bright, or rejecting the same amount |
Of sunlight. The seas" Of the satellite |
its great, deep level valleys-give only |
three-fourths as much light as its high |
mountain peaks.
Besides the more exact instrumental |
methods of study, visual observations |
Of the moons surface are being made |
by members of the committee through |
the 100-inch telescope.