The Salt Lake herald. [volume] (Salt Lake City [Utah]) 1870-1909, 1892-09-01
GAZING AT MARS.
Professor William Pickering Of
Harvard Is Stationed at Peru.
THE MOVEMENTS OF THE PLANET.
The Professor Writes to an Astronomical
journal Explaining The Great Varsity
of Colors, Etc, of the Planet Mars

Especial to THE HERALD-Examlner Dispatch
NoRTHFIELD, Min, Aug. 31.-Prof. Will
liam Pickering, director Of the Harvard
college observatory, who is stationed at
Arequipa, Peru. observing the opposition
of Mars, has written as follows TO Astron
omy and Astrophysics, the astronomical
journal published here:
have previously called attention to the i'm
portant effects OF our own atmosphere in mis-
leading judgment as to the colors exhibited by
the heavenly bodies. A good illustration OF
this may be obtained from mountain summit
on cloudy day. The distant greens Of the
landscape are at once changed TO gray by the
passing OF very thin mist between them and
the eye In the former case they be-
come darker. and in the latter lighter,
but in neither case the greenish hue
entirely disappears. The sudden changes OF
color exhibited by some of the smaller areas
upon the planet of Mars are sometime almost
startling. recent viewlwas obtaind shortly
before sunrise. when The snowy region
about the south pole appeared of a
most brilliant green, quite equelling in
color the rather narrow green band situated
just to the north OF 1t. Later as the sun came
up the color of the snow changed to bright
yellow the rest OF the disc changing in the
uedullme 10 orange. Later several OF the
canals became visible. and the snow became as
coloriess IS upon our surrounding mountains
Ihe Two former effects were probably due to
bad seeing, the fluctuations OF our own atmoS-
phere super-poring the colors OF the surround
ing regions upon the snow. We have lad it
down as o rule never to rely greatly upon our
color observations unless the snow caps OF the
planet appear perfectly colorless, and the canal
system Is well defined These conditions we
find always combined with the best seeing. For
these delicate color observations it will there
fore be seen that not only do we require tel
escope of the best quality, but also the very
best obtainable atmospheric conditions.
In studying the smaller dark regions, such
as the northwestern part OF the Syrtis Major.
great differences of color have been noted from
night to night and have colored sketches in
my possession taken at different times, In
which 1t is represented as gray. as green, as
blue, as brown, ana even as violet. The latter
color was SO extraordinary that I endeavored
TO make that portion Of the planet appear to
my eye of some other color. but 1t was lmpos-
sible, and no other color but violet could be
made TO match il. This color upon the planet
has been only seen By me once since. The
brown color above noted was undoubtedly due
to bad seeing. At one time felt convinced
that the red color OF the darkest shots upon the
planet was deep blue, and this may In reality
be the case But OF late un Ter favorable cir
cunstances, they have appeared to me to be Of
an absolutely colorless grey.
The most striking marking upon the planet,
and that most readily seen with small tele-
scope is the Syrtis Major or Y mark. This is
nearly central in the sixth position of the
planet. This region in 1891 was interesting as
containing the most conspicuous canals visible
upon the planet, excepting the large one which
terminates the Syrtis Major upon the north.
Al this opposition these canals are TOO TAR
north TO be well seen. The fourth and third
regions of the planet are both uninterestlng.
The second position is interesting, as showing
the great southern ocean, which IS neariy as
conspicuous as the Syftis Major itsef
We now come to q curious feature of the OBJ
servations. namely, the actual change in color,
which, eliminating all probable sources of error
the planet really seeing to UNDERGO. when the
Syrtis Major Is central, before the autumnal
equinox of the northern hemisphere, the region
TO the east is seen to be more greenish than
to the west.
The two arms OF Syrtis are not OF equal
breadth. the eastern arm being nearly twice as
wide as the western arm. Early in 1890 the entire
region enclosed between the arms OF the yrts
Major, as far as the snow cap, was of brilliant
green color. Eleven days before the vernal
equinox OF the southern hemisphere, a yellow
spot appeared st the extreme northern point of
the triangular area. AS the senson advanced
this yellow spot increased In area Till 1t covered
the whole region as far south as could be seen
This year when first observed, this area was
entirely green but on May g. or seventeen days
before the vernal or equinox the yellow, or per-
haps reddish spot, appeared in the same place.
and 1t Will be interesting to determine as the
season advances II this color again advances
toward the pole.
Changes to the east OF the Syrtis Major have
also been noticed by Schiaparelh These he
ascribes TO ext nsive floods. On June there
was large greenish areavisibe in long tude 49,,
latitude 80 north. and by July 16 this spot could
not be found. The large crescent-shaped area
in the northern part OF the planet at one time
was quite dark, yet on one evening It was
painted green and the ocean to the south OF il
blue, the difference in color one evening being
very clear. On March % OF the present year
the crescent was well shown, but was decidedly
fainter than the ocean. which was again sus-
pected OF being blue. but the color could not be
satisfactorily confirmed. The crescent now is
too far north, owing 10 the motion Of the
planet to be satisfactorily studied.
Professor Pickering says that he be-
lieves that in the future the changes will
be thoroughly understood and laws be ad-
duced affecting them. He thinks the
greatest danger lies from optical illusion.