Evening star. [volume] (Washington, D.C.) 1854-1972, 1909-09-23
ALL TO WATCH MARS
Planet Will Be Nearest the
Earth Tomorrow.
ONLY 49, 1000, 900 MILES OFF
Startling Discoveries Expected With
New Telescopes.
NAVAL OBSERVATORY READY
Big Results Anticipated at Flag
staff, Ariz.-May Settle the
Oxygen Controversy.
NAVAL OBSERVATORY READY

Tomorrow will be great day for as
tronomers, for every telescope will be
pointed at the most Interesting planet of
the solar system-Mars-which will ap-
proach the earth within 81, 100000 miles.
Astronomers at the United States Naval
Observatory here have made the neces-
sary preparations to make new discover
les If possible. This event is especially
interesting to Americans, for it was at
the national observatory that the satel-
lites were first discovered by Prof. Asaph
Hall thirty-two years agO-August. 1917
at a periheiion opposition Of the planet
The great telescope at the naval OBJ
servatory is now in charge of Prof. Asaph
Hall, jr.. a son of the man who earned
SO much fame for American astronomy.
Observations of the spectrum of the
planet at this opposition will be the chief
concern of astronomical research at all
the observatories of the world, inasmuch
as the oxygen and water theories in the
atmosphere of the planet remain a matter
of astronomical dispute.
Director w. w. Campbell of the Lick
observatory has become satisfied that
oxygen and water vapor in the atmos-
phere of the planet did not exist in suff1-
cient quantities to be detected by the
spectroscope las then available" al
Though the method is very sensitive one.
Thought They Saw Oxygen.
Prof. Campbell refers to the study Of
this subject by such eminent scientists
as Prof. Higgins and VOCAL and others in
the sixties and seventies, and by himself
as late as 1S94-95.
For the past twenty years those OBJ
servers thought they saw in the spectrum
of Mars evidence of oxygen and water
Qfm0Snhpro
the earth's sister planet was regarded as
authority, and astronomers generally
agreed that the earth and Mars were
more nearly alike in constitution than
comes Prof. Campbell, with the fino
equipment Of the Lick observatory. and
upsets this established view of the ap
pearance of the planet. 1t seems that
this discovery was made by the aid of
improved dry plates Of modern celestial
photography. which heretofore could not
be studied by the early observers of Mars.
Prof. Campbell quotes the words Of Mr..
Slipher OF the Lowell observatory at
Flagstaff. Ariz.. whose observations of
absorption not found in that Of the moon
photographed under the same conditions.
This conclusion from the Lowell OBJ
servatory confirming the visual observa
tons OF Prof. Campbell in 1894. and of
his Photographic work in 1895, and of
Prof. keeler's Photographic work Of 1897,
are all opposed to the we'll known theories
Of Profs.. Higgins, VOCAL, Maunder and
others.
Astronomer Perceval Lowell, who has
made the study of the planet Mars the
chief object of his scientific effort for the
past fifteen or twenty years, will posi-
bly, be the best equipped observer in the
world to take advantage OF the approach
tomorrow. when it's apparent diameter
will be such as will enable DR.. Lowell to
test his new forty-inch rejecting tele-
scope on the largest sized disk of the
planet that 1t has ever been his fortune
to observe.
This great reflector has just been COM
pleted and placed in position at Flag
staff. Ariz. The instrument Is designed
for planetory photography and astrono-
mers both in the United States and
the Arizona observations.
A Big Telescope, This.
The focal length of the great telescope
Is eighteen feet four inches and the mir
ror, cast at st. Gobian, in France, 10
seven inches thick and weighs more than
300 pounds. The cell Is an iron ring
with zinc blocks so arranged that the COM
bined expansion is the same as that of
the glass. thus obviating distortion For
planetory photographs the reflector can
be used as a Cassegraln Of 154 feet or
IS feet focal length. while for stars and
nebulea 1t will be used as a Newtonan
with the plate at the principal focus The
instrument is protected from temperature
changes and wind by being sunk six feet
into the ground. over which Is erected a
hemispherical dome of wood and canvas.
This is perhaps the most complete equip
ment of its character in the United States.
1t Is possible that Dr., Lowell with his
great rejecting telescope equipped espec-
tally for planetory photography may
secure at this perihelion opposition i'm
prints. of Mars that may counterpart in
the scientific world the discovery of the
north pole.