Evening star., 1939-07-28
By r. S. RICHARDSON.

MOUNT WILSON, Calf, July %
NA.N.AD.-I observed Mars at 3
am. Pacific Coast time), just 10
hours before the moment of closest
approach. The red planet was then
at distance of only 36,030 900 miles
closer than at any time since
August, 1924. Seventeen years must
pass before it will be as near as this
again.
A magnification of 400 was used on
the telescope, bringing Mars within
an optical distance of 10000 miles, or
less than half the distance to the
moon. AS seen in the field of view,
Mars resembled a pinkish-colored
globe on which some artist had
amused himself by painting strange
designs with poor brush.
No canals could be detected with
certainty. In the equatorial regions,
however, faint streaks were glimpsed
occasionally, but no fine lines ap-
peared such as those described by
the two famous men of Mars, Schia-
parelli and Lowell.
Polar Cap Is Shrinking.
The south polar cap is beginning
to shrink with the approach of sum-
mer in that hemisphere. The season
on Mars now corresponds to about
October IS on the earth. There is
dark blue border surrounding the
cap, attributed to marshy ground
formed by the melting snow The
rapidity with which the cap shrinks
leads one to believe that the deposit
cannot be more than a few inches
thick.
The south polar cap has been
known to vanish completely, but the
northern one never quite disappears.
This is because Mars is 25,OO0,0O
miles closer to the sun during the
southern summer than when the
Northern Hemisphere is turned SUM-
ward
A portion of the north polar cap
could also be seen, but Mars IS
tilted at such an angle with re-
spect to the earth that its full ex-
tent cannot be determined. 1t gave
the impression OF being much larger
than the south polar cap.
The gray-green areas in the
southern hemisphere were a con-
spicuous feature. They show distinct
shades of color within themselves,
ranging from a pale green to dark
olive. I clearly discerned several
of the little V-shaped markings
called carets on the northern border
of this greenish area. HaZy streaks,
possible canals, at time appeared to
project from the carets, but OF this
I could not be sure. The green re-
gions are believed to be some sort
of vegetation, for they change color
with the seasons in a way that
would be expected of plant life.
Dark Spots Seen in Deserts.
The northern hemisphere is DOM
mated by the vast ochre- -colored
deserts, except for an occasional
isolated dark spot. These broad
de-erts, which cover over 60 per
cent of the surface, give Mars its
name of the red planet. A per-
petual drought exists there, worse
than any we have ever experienced
on the earth. All the water that
remains on Mars is in the form of
ice and snow at the poles. 1t has
been estimated that it could easily
be emptied into the Great Lakes.
During the observations the mark
ings were slowly shifting their po-
sition on the disk. New ones were
coming in around the right-hand
edge, while others were disappear
ing over the opposite side of the
planet. This is not an optical illu-
sion, but simply the result of the
planets rotation.
Although today is regarded as a
sort of deadline after which Mars
will cease to be of interest, actually
it will continue to be the brightest
star in the early evening sky for
another month and the object Of
intensive study at observatories all
over the world