The Jasper weekly courier. [volume] (Jasper, Ind.) 1858-1922, 1909-10-22
{ INSTANCE OF THE STARS.
49,. Astronomers Set About the Tasl
Of Measuring II.

Of Mezsurlng t.
Vrb the exception Of hundred
.,,. AZ most, we know nothing OF
,sa distances Of the individual stars.
What ia the cause of this state OF
hiogs2 II is owing 10 the fact that
70 have two eyes that we are en-
.blsd not only TO perceive the di-
-sction in which external objects
s,s situated. but to get an idea OF
,ssir distance. to locahze them In
,nace But this power is rather linn
IA For distances exceeding some
hundreds Of yards il utterly fails.
rbo reason is that the distance be-
tween the ewes as compared with
,be distance TO be eyaluated be-
comes TOO small. instruments have
baep devised by which the distance
bstveen the ewes is, as it were, artl-
fcially increased. With a good in
.trrment Of this sort distances OF
.sreral miles may be evaluated. For
still greater distances we may i'm
srinc each eye replaced by photo
graphic plate. Even this would be
oujte sufficient for one Of the heav-
toly bodies-viz, for the moon.
IL one and the same moment let
a photograph of the moon and the
surrounding stars be taken both at
ne Cape observatory and at the
loyal observatory at Greenwich.
Facing the two photographs side by
side in the stereoscope, we shall
clearly see the moon Hanging in
space" and may evaluate its dis
lance.
But for the sun and the nearest
planets, our next neighbors in the
universe after the moon, the diff
cultv recommences.
The reason is that any available
distance on the earth, taken as eye
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
tE stereoscopic examination, as
ironomers have succeeded in over
coming the difficulty for the sun. j
think We may say that at present
We know its distance to within q
thousandth part of its amount.
Knowing the suns distance, We get
that Of all the planets by 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 eye dis
lance on our earth. Meanwhile our
success with the sun has provided
Us with new one distance, "a, 900
tines greater than any possible eve
distance on the earth, for now that
We know the distance at which the
earth travels 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
sPart will represent the stellar
world as seen from points the dis
lance between which is already best
expressed in the time it would take
light to traverse it. The time would
besbout sixteen minutes.
However, even this distance, i'm
nense as il Is, is, on the whole, in
adequate for obtaining a stereo-
scope view Of the stars. 1t is only
N quite exceptional cases that pho
@ographs on large scale-that is,
OOIalned BY the aid OF big tele-
sOpes-show any stereoscopic ef-
'ec' Tor fixed stars. By accurate
Measurement Of the photos we may
lefAaps get somewhat beyond what
secan attain by simple stereoscopic
Inspection; but, as we said a mo-
@ent ago, astronomers have not sue
.eeded in this way in determining
ne distance of more than a hun
u'ea stars in all.-Scientific Ameri-
can