Evening star., 1939-02-07
Of Stars, Men
And Atoms
Notebook of Science Progress
In Field, Laboratory
And Study
BIZ Thomas r. Henry.

6y IHOHlUS II. f7eUIy.
The planet Venus, theoretically the
most probable abode of living things
outside the earth, may be the dust bowl
of the solar system.
Observed from the earth it Is covered
with dense, deep clouds through which
no light can penetrate to give astrono-
mers glimpse Of its surface. The pos
sibility that these are, In part, great
dust clouds is advanced by DR.. Theodore
Dunham, jr., astronomer of the Carnegie
Institution of Washington, In volume
of memorial essays prepared in honor Of
DR.. John c. Merriam, retired president Of
the institution.
Venus is 100000 miles closer to the
sun than the earth and consequently its
normal temperature would be much
greater. Also 1t is lighter and hence has
less gravitational attraction for the
lighter elements in its atmosphere. At
a very early period in its history most
of the hydrogen necessary for forming
water may have escaped.
The nature of the Venus clouds, DR..
Dunham says, constitute one of the
great unsolved problems of planetary
astronomy. There still may be some
possibility of penetrating the great
clouds by some kind of long wave radia-
ton so that 1t will be possible to photo
graph some details of its surface. The
only substance positively detected in the
Venus atmosphere to date is great deal
Of carbon dioxide the gas used by plants
in the basic process Of photosynthesis.
Dust bowl or not, astronomers con-
slider the possibility of life on Earths
nearest neighbor planet as very remote
even less probable. in fact, than that of
some low form of life on cold, almost
airless Mars on the other side of the
Earth from the Sun.
The composition of the atmosphere on
all the planets as it is now known, DR..
Dunham says, is exactly what might
have been predicted in advance.
According to the most generally ac-
cepted theories they are formed of mat
ter which originally was torn loose from
the gaseous outer layers Of the sun
Hence there is essentially nothing in
them that is not in that solar atmos-
phere. Its composition is well known
1t contains about everything ever found
on Earth in essentially the same pro-
portions except for the light gas hydro
gen-lightest Of elements and probably
the parent stuff Of all creation.
The major planets, Jupiter, Saturn
Uranus and Neptune, exert a tremendous
gravitational pull because of their great
masses. The free hydrogen molecules
could not float free of this attraction
and hence were retained in the atmos-
phere where they combined with atoms
OF the other and heavier elements
oxygen, nitrogen and carbon. The first
combination resulted in water, formed
at the highest levels. On Jupiter, at
least, this crystallized into ice and fell
to the surface. due to the intense cold
because of the planets great distance
from the sun.
This left at the top of the atmosphere
the next lightest gas formed by the
hydrogen-nitrogen combination - or
ammonia. A little Of this remained as a
gas, more was transformed by the in
tense cold into ammonia-ic particles
These probably constitute the majority
OF the great clouds Of Jupiter. Below
was the next lightest combination, that
OF hydrogen and carbon, or methane
familiar on earth was marsh gas II
probably constitutes the atmosphere OF
Jupiter below the clouds.
On the most distant planets, with their
more intense cold, the majority of the
ammonia in turn was frozen out and fell
These far-off bodies may have coats oi
ammonia above their undershirts OF
waterloo. The methane gas became
their upper atmosphere. Great depths
Of the marsh gas are shown by spectre.
scopic studies.
Three planets-Venus, Earth and
Mars-were sufficiently light to let 8
good deal of their hydrogen escape. Thu.
1t was not available to combine with
oxygen and form water. The oxygen
was lett free IN the atmosphere. Hence
these three planets have the only DOS.
sible atmospheres which could support
human life. Earth has plenty of It
Venus possibly has let altogether toe
much hydrogen escape, and conse.
quently may have too little water tt
support life. Earth's weight was ideal
so as to insure just enough oxygen tr
the air and just enough water to serve
the needs of living things.
Mars, it is now believed, once hac
plenty OF free oxygen in its atmosphere
but most OF this now has been combined
with iron, forming iron oxides which
give the planet its Enthusiastically rec
color.
The tiny planet Mercury and all tn,
moons OF the solar system are 80 small
that they were not able to retain an,
gasses in free state by their gravita.
tional pull They are devoid Of an,
atmospheres.