The Jasper weekly courier. [volume] (Jasper, Ind.) 1858-1922, 1911-05-12
DISTANCE OF THE STARS.
How Astronomers Set About the Task
Of Measuring IL.

OF Measuring II.
With the exception of 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-
abled not only 10 perceive the d.
rection in which external objects
are situated, but to get an idea OF
their distance, to localize them in
space. But this power is rather lin
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
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
quite sufficient for one of the heav-
enly bodies es-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 Cape observatory and at the
Royal observatory at Greenwich.
Placing the two photographs side by
side in the stercoscope. we shall
clearly see the moon changing in
space" and may eyaluate 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 on the earth, taken an eve
distance, is rather small for the
purpose. However, owing 10 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 well
known relation existing between the
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
question Of any sufficient eve dis
lance on our earth. Meanwhile our
success with the sun has provided
is with new one distance, "a, ZOO
times greater than any possible eye
distance on the earth, for now that
We know the distance at which the
.arth travels In its orbit around the
nun we can take the diameter Of its
,rbit as our eye distance. Photo
yraphs taken at periods six months
part will represent the stellar
world as seen from points the dis
ance between which is already best
in the time il would take
light TO traverse it. The time would +,
'e about sixteen minutes.
However, even this distance, i'm
nense as il is, is, on the whole, in
dequate for obtaining stereo-
copic view Of the stars. 1t is only I
n quite exceptional cases that pho
ographs OH a large scale-that is, I
blamed by the aid Of big tele-
copes-show any stereoscopic ef-
ect for fixed stars. BY accurate
Measurement OF the photos we may
erhaps get somewhat beyond what
'e can attain by simple stefeoscopic
but, as we said a mo-
lent ago, astronomers have not sue
eeded in this way in determining
he distance of more than hun
red stars in all.-Scientific Ameri-
IN.
Abss~<mInded.