The Jasper weekly courier. [volume] (Jasper, Ind.) 1858-1922, 1913-03-07
O'sTAScEs4aI THE STARS
How Astronomers Set About the TssA
CT Msasurino Il.

Of Measuring lt.
With the exception of hundred
stars at most, we know nothing OK
khs>diStances Of the individual stars.
What is the cause OF this state OF
thiDgs! 1t Is owing 10 ale fact that
we have tao eyes that We ere en-
abled not only to perceive the di-
rection in whiel external ob. ects
are,stuated, but to Get an idea o.
their distance, tn locslize them in
space. But this power ]. rather linn
tied. For distances exceeding some
hundreds OF yards it utterly fails.
The reason is that the distance be-
tween the eyes as compared with
the distance to be evaluated be-
comes too small. instruments have
been devised by which the distance
between the eyes is, as 1t were, ara
fcially increased. With a good in
strument of this sort distances OF
several miles may be evaluated. For
still greater distances We may i'm
agine each eye replaced by photo
graphic plate. Even this would be
quits sufficient for one Of the heay-
enly bodiss-viz, for the moon.
At one and the same moment let
a photograph of the moon and the
surrounding stars be taken both at
the CaHs observatory and at the
Royal observatory at Greenwich.
Placing the two photographs side by
side in the stereoscope, we shall
clearly see the moon Hanging in
space" and may evaluate its dis
tance.
But for the sun and the nearest
planets, our next neighbors N the
universe after the moon, the diff
Guilty recommences.
The reason is that any available
distance On the earth, taken as eve
distance, is rather small for tho
purpose. However, owing to in
credible perseverance and skill Of
several observers and by substitut-
ing the most refined measurement
for stereoscopic examination, as
tronomers have succeeded in over.
coming the difficulty for the sun. I
think we may say that at present
we know its distance to within .
thousandth part OF its amount.
Knowing the suns distance, we get
that Of all the planets By a we'll
known relation existing between tho
planetary distances.
But now for the fixed stars,
which must be hundreds of thou
sands of times farther removed than
the sun. There evidently can be no
of any sufficient eye dis
tance on oHr earth. Meanwhile our
success with the sun hds provided
Us with a new one distance, "a, 600
times greater than any possible eye
distance on the earth, for now that
we know the distance at which the
sarth travek in its orbit around the
sun we can take the diameter. of its
orbit as our eye distance. Photo
graphs taken at periods SIX months
apart viii represent tho stellar
world as seen from points the dis
tance between which Is already best
expressed in the time It would taxa
light to traverseit. The time would
be about sixteen minutes.
However, even xhis distance, i'm
nense as it is. Is, on lie whole, in
adequate for obtNnlng stereo-
ecopic vics- - he stars. II is only
hsquits ,y"er nj case hat pho
tographs - = scsie-that is,
obtained b. ~ nd Of big tele-
scopes-show a. stereoscopie ef-I
feet for fxed sta BY accurate
mensurenc cnt of the photosswe paay
perhaps get somewhat beyond what
we can attain by simple microscopic
inspection; but, as we said a mo-
nent ago, astronomers have noe suc-
eeeded ia this way IN determining
khe distance. of more than a hun
dred stars In all-Scientifc Ameri-