Evening star., 1939-07-23
Blue Light Photos
Reveal Changes
On Planet Mars
Astronomer Slipher
Is Now in Africu to
Observe Behavior
By HOWARD w. BLAKESLEE,
Associated Press Science Editor.

Associated Press Science Editor.
FLAGSTAFF, Ariz., July "a
Mars canals" and the peculiar
markings seen when the planet is
photographed in blue light were
described today by associates here
at Lowell observatory of Earl c.
Slipher, the Martian expert who is
in South Africa now watching the
red stars close approach to earth.
Astronomer Slipher, stationed at
Lowell observatory, has looked at
the markings on mars more than
any other living man. Two days ago
he reported from South Africa that
he sees strong evidence of the ex-
istence of plant life on Mars.
At the present time, because of its
position on the sky, Mars has ex-
panded In a powerful telescope to
about five times the diameter of our
moon as seen by the unaided eye.
This Is far larger than usual. More
over Mars is twice as bright.
Shpher went to South Africa, to
the Bloemfontein Lamont -Hussey
observatory of the University of
Michigan, because Mars is directly
overhead in the Southern hemis-
phere and the view is much better.
In the United States Mars is visible
each night low IN the Southern sky
Ordinarily the canals of Mars can
be seen only internationally, usually
in piecemeal. In 80 years Slipher
has seen enough, however, to make
1900 drawings of them.
800 Markings Observed.
To date about 300 markings have
been observed. Two hundred were
named but the remainder have been
designed by numbers. About nine
tenths are straight lines. They are
segments OF great circles, the lines
that would be made at his surface
by plane passing centrally through
the planets globe.
The lines run from 200 miles to
1000. Early in the studies observers
hazarded the guess that these lines
were canals carrying water Some
came from around the white areas
near Mars poles that are obviously
snow or frost caps. Some ran
through the darker areas, that may
mean vegetation, which are gen.
orally pale in Mars winter and
darken their rues and expand In
areas in his summer.
The long rivers" have straight
cross-lines emptying into them at
angles from As to 80 degrees. Most
Of these not only empty into the
main canal but go directly across it.
In between these cross-lines, when
seeing" Is at its best, Slipher has
observed what seems to be lot of
detail"
He does not say what the canals
may be, except that they behave as
would strips of vegetation. He is
more interested in the complete
story of their changes and behavior
as told by hundreds of thousands
OF photographs of the planet because
it is from the law of change that the
astronomer expects eventually to
understand conditions on Mars.
Photographs show what astrono-
mers early called seas, dark areas
often of greenish hue, now taken
to be possible vegetation and GER
talnly huge surface markings. It
has been suggested that Mars at
mosphere, existence of which is we'll
verified. plays occasional tricks with
light that might account for SEEM
ing markings.
But recently Slipher obtained
what he believed was striking proof
that even possible tricks of light
were not the cause. This was in
photographs taken through a blue
filter. Such photos failed for many
years to show Mars surface.
Took Pictures of Paintings.
To learn the cause, Slipher took
photos in blue light of paintings of
Mars by Howard Russell Butler, In
this light, the markings on the
paintings disappeared exactly as in
blue pictures of the planet itself.
This fact at first seemed to verify
the suspicion that in some lights the
apparent surface markings were
tricks of Mars peculiar colors.
But in 1887, for month, the blue
light photos of the planet showed
the Martian surface distinctly.
They showed the same kind of
markings there that have been seen
in other colors of light. What hap
pened to make the Marian atmos-
phere so clear with the blue light
is not known,
This is only one Of numerous
questions the students of the planet
are going to be deeply occupied
with these weeks vhile the raIddv