The Denison review. [volume] (Denison, Iowa) 1867-current, 1909-11-10
The PARKWAY STARS

The PARKWAY STARS
Their Color Serves as an Index
to Their Age.
WHAT MAKES THEM TWINKLE?
Two Theories That Deal With This
Astronomical Enigma-The Interview
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 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 as 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 instru-
ments.
To illustrate. then. my meaning as
regards this covering Of the visual
angle. suppose. you take dime be
tween your thumb and finger and hold
It between your eye and the moon un-
til It just covers the moon. 1t will be
found to be quite close to the eye. Now
take 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 dime or even pin
head. and no matter how far you hold
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 1t. So
thus we see that this theory is not Inn
possible, though perhaps somewhat i'm
probable.
The other theory bases its argument
on the air currents. Air currents are
caused by light aud heated air rising
f and cold and heavy air taking Its place.
Now. when light goes from heavy
to 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 ii
does in the zenith. for its light has to
come through greater thickness of
atmosphere; also greater twinkling is
observed III winter than in summer,
and when rapid and brilliant twinkline
is seen it is very good prophecy ol
rain or snow. as 1t shows the upper re-
gions of the air to be in a state Of
rapid motion Of varying air currents
hot and cold currents meeting. com.
mingling and rotating probably.
This also accounts for the changes
In the brightness Of q star. for at times
part aud not all Of its light is ben,
away from the eye. 1t. has been no
ticed also that stars color has some
thing to do with its twinkling gu ac:
count Of the different refractivities Of
the different colors. A white or blue
star. such as the Dog star. twinkle.
most; next comes the yellow and las
the red. II one cares to look for RED
star. Betelgeux is one, aud can be
found in one corner Of the constella
ton Orion.
A rather interesting thing has beer
ascertained in astronomy as regards
the relation between the color of a 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 go out In the next few million
years. See IL 1t 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 i:
classified as white star. A. L
Hodges in Cincinnati Commercial Trib
une.