Bismarck daily tribune. [volume] (Bismarck, Dakota [N.D.]) 1881-1916, 1909-11-05
THE PARKWAY STARS
Their Color Serves as an Index
to Their Age.
WHAT MAKES Them TWINKLE?

Two Theories That Deal With This
Astronomical Enisma-The lnterven'
| ton of Fragments Of Disrupted
Worlds or the Effect Of Air Currents
This is a question that has exercised
more than one gentleman of science
OF course it is known that only the
stars twinkle, the planets giving out
a steady light. That is the way we
tell a star from a planet with the
| naked eye.
But why does the star twinkle at all:
The answer to this seems to be on ac'
count Of the greater distances of the
stars, the nearest fixed star being sew
eral thousand times farther from us
than the farthest planet. So around
this as starting point have been built
two theories. One is that rs the
visual angle, or angle subtended by
the star from the eye, is so very small
that very small bodies in space com
ing between the star and the eye
would give the effect of twinkling.
Now, as regards those small bodies
actually being in space as hypothecat-
ed there is no doubt, for there are mil
lions of fragments Of disrupted worlds
flying around in orbits about our sun.
The only question is whether there are
enough to cause the eternal twinkling
that is observed. Science cannot say
that enough do not exist, for she can
not perceive the existence Of the small
est fragments that actually could cause
this effect, even with her finest insrru-
ments.
To illustrate, then, my meaning as
regards this covering Of the visual
angle, suppose you take a dime be-
tween your thumb and finger and hold
it between your eye and the moon I'M
til it lust covers the moon. 1t will be
found to be quite close to the eye. Now
take a quarter and hold it so that 1t
just covers the moon. Its distance is
at once seen to be about four times the
dimes from the eye. Thus it Is seen
that the farther outward the object Is
placed the larger the object necessary.
This is in accord with what is known
as the law of inverse squares.
But now take a dime or even a pin
head, and no matter how far you bold
it from the eye it will easily cover the
largest star in the heavens. This Is
on account Of the enormous distance Of
the star, the lines drawn from its sides
to the eye inclosing an angle so minute
that almost anything will fill it. So
thus we see that this theory Is not Inn
possible, though perhaps somewhat Inn
probable.
The other theory bases its argument
on the air currents. Air currents are
caused by light and heated air rising
and cold and heavy air taking its place.
Now, when light goes from a heavy
to a light gas. or vice versa, 1t Is bent
one way or the other. So this would
certainly happen to the light from all
the heavenly bodies. The reason it IS
not noticed in the case Of the planets
or the sun is that they send us many
more rays as compared to the stars.
Many reasons are put forward to
show the truth Of this theory. A star
wrinkles more on the horizOn than 1t
does in the zenith, for its light has to
come through greater thickness of
atmosphere; also greater twinkling is
observed In winter than In summer,
and when rapid and brilliant twinkling
lis seen It is d very good prophecy OF
rain or snow. as it shows the upper re-
gions of the air to be In q state Of
rapid motion of varying air currents.
hot and cold currents meeting. con-
mingling and rotating probably.
This also accounts for the changes
in the brightness Of a star, for at times
a part and not all of its light is bent
| away from the eye. 1t has been No.
ticed also that stars color has some.
thing to do with it's twinkling on ac-
count of the different refractivities OF
the different colors. A white or blue
star, such as the Dog star. wrinkles
most; next comes the yellow and las,
| the red. If one cares to look for red
star, Betelgenx is one and can be
found in one corner of the constella-
| ton Orion.
A rather interesting thing has been
ascertained in astronomy as regards
the relation between the color Of star
and its age. The white or blue stars
| are considered young or in the prime
of life. with many more million years
! to their career, while red star. as
Betelgeux, is on the wane and will grad.
ually 60 out in the next few million
| years See. If it doesn't! The yellow
stars of course come between the blue
and the red in point of age. 1t is en-
| couraging to find that our own sun is
classified as a white star. 49, A. L.
Hodges in Cincinnati Commercial Trib
une. - ...
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f. S ~. { ? D., r-sE
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