The Jasper weekly courier. [volume] (Jasper, Ind.) 1858-1922, 1915-04-02
DISTANCE ,oF THE STARS.
How Astronomers Set About the Task
Of Measuring II.

How Astronomers Set About the Task
Of Measuring II.
/ With the exception of a hundred
stars at most, We know nothing of
The distances of the individual stars.
What is the cause of this state of
things? 1t is owing to the fact that
we have two eyes that We are en-
ahled not only to perceive the di-
rscton in which external objects
are Situated, but to get N idea Of
their distance, to locali,s them in
space. But this power is 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 it were, arti-
fcially increased. With a good in
strumcnt cf This sort distances Of
several Gi,~ maf be evaluated. For
still greater distances we may i'm
agine each eve replaced 10y photo
graphic pl; te. Even this would be
quite suiii, cnt for one Of the heav-
enly bodie viz, for the moon.
A. one and the same moment let
a photograph of the moon and the
surrounding stars be taken both at
the Cape 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 in the
universe after the moon, the diff
Guilty recommences.
The reason is that any available
distance OF the earth, taken as eve
distance, is rather small for the
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 a
thousandth part of its amount.
Knowing the suns distance, we get
that of ell tie planets by a we'll
known relation existing between the
planetary distances.
But noE- for the fixed stars,
which must be hundreds Of thou
sand Of times farther removed than
the sun. There evidently can be no
question Of aHv sufficient eye dis
tance on our earth. Meanwhile our
success with the sun has provided
Us with new one distance, $4,000
times greater han any possible eye
distance on thc earth. for now that
We know the Gnce at which the
earth travels in orbit around the
sun we can take tie diameter of its
orbit as our eve distance. Photo
graphs taken : neriods six months
apart Will repent the stellar
world as seen frcl points The dis
lance between whi,h is already best
expressed in the time it would take
bght to traverse it. The time would
be about sixteen n Hutes.
However, even tbs distance, i'm
Uense as it is, is, on the whole, in
adequate for obtaining a stereo-
scopic view of the stars. 1t is only
h quite excel ional cases that pho
tographs on .lrge scale-that is,
obtained by the aid of big tele-
scopes-show any stereoscopic ef-
seet for fixed stars. By accurate
measurement of the photos We may
perhaps get somewhat beyond what
Ee can attain b simple steieoscopic
but, as we said a mo-
nent ago, astronomers have not sue
seeded in this way in determining
the distance of more than q hun
dred stars in all Scientific Ameri-
can