The Mount Holly news. [volume] (Mount Holly, Burlington Co., N.J.) 1891-1942, 1910-04-05
COLOSSAL ARCTURUS
The Fourth Brightest Star In All
the Heavens.
IN REALITY A MONSTER SUN.

Il 10 Thought to Be at Least a Hun
dred Times Larger Than Our Sun In
Diameter ard Is About Nine Hun
drsd and Fifty Million Miles Distant.
Most of US are prone to think of our
sun as being the largest body in the
heavens, the grand high lord of all the
little planets and the twinkling stars.
Such is very far from being the case.
Practically all of the fixed and twin
king stars are as large as, and some
even larger than, our own sun. They
appear small only because of their great
distance, for they are just as truly
suns with families of planets flying
around them as is our central orb.
There is one of these stars in par
ticular that has attracted the atten-
ton of astronomers, not only on ac-
count of its great size. but also its
enormous distance from our solar sys-
tenn. This is the star Arcturus. To
have some conception of the almost in
conceivable distance that separates it
from us the astronomical standard Of
measuring distance must be compre-
hended. Now, light does not come
from luminous body instantaneously
to our eyes 1t takes time to come,
because it is a wave motion in a
medium. The velocity of light as
most recently determined is about
10000 miles a second. Multiply this
by the number of seconds in a year
and we have a distance known in as
tronomy as a light year. Therefore
when star is, say. six trillion miles
away we say it is one light year off.
which means that the light from the
star takes one year to reach US. 1t
may be Of some interest to know that
there Is no fixed star less than ten
light years away, or sixty trillion
miles. This Is the one known as Alpha
Centauri Most of the stars are much
farther even than that, Arcturus being
the farthest one measured to date.
| Arcturus is thought to be at least
hundred times larger than the sun
| in diameter. That would make it
| 10000 times larger in surface, OF the
dimension that is ordinarily compared.
| By means of the photometer its bright
ness has been determined to be 6.2OO
| times that of the sun. 1t is the fourth
brightest star in all the heavens, Siri-
us. the dog star, being first in bright
ness. AS regards the distance from
us, it has been found to be little over
| 100 light years, or $50 trillion miles,
This distance. of course. cannot be
conceived by mortal man, 1t is so stu
pendous and amazing. However, one
can get slight idea of 1t by means Of
an everyday analogy. Think of the
fastest express train going at the rate
of 100 miles all hour toward such a
star and compute the time it would
take. 1t is found to be in round num-
bers exactly 120000OOO years. Now,
as we know that it has taken its light
SO long to come to us and as there are
great many stars whose distance
has never been measured exactly. but
which have been computed to be APP
proximately several million light years
away, we have absolute proof of the
great age of the world and the stellar
universe.
The elements composing the sun Arc
turus are. peculiarly enough. very
nearly the same as our sun. As it is
one of the most wonderful and as
founding things that a scientist can
tell what a star so far away is COM
posed of, small explanation of the
modus operandi would not come amiss
here. 1t is done by means Of small
instrument known as the spectroscope,
which consists of glass prisms so ar.
ranged as to split up the light falling
on them into its constituent parts.
Now, every substance has the power
to cause certain color or line in the
spectroscope if 1t is in a luminous con-
dition, so this instrument is simply
pointed at the star whose composition
is sought, and if any line is found that
corresponds to q substance that we
know about we assume that this sub
stance is found In the star examined
Another interesting thing is the meth
cd pursued in determining the great
distance Of the stars. This is done
by determining their parallax or angle
made at the star between two rays
from the star striking at two differ
cut pOluLS III SpdCe AS tue greatest
distance that we can measure off In
this way and still take the angle is
the diameter Of the earth's orbit. that
distance is invariably used 1t is al
most 200,OOOOOO miles. but that as is
seen, is very small compared with the
enormous distance Of the star. Now.
the angle thus measured from Arc
turus is only two-hundredths Of a sec
ond! When it is remembered that
there are 60 seconds in a minute, 80
minutes in a degree and $50 degrees
in circle, it is at once seen what
small angle the parallax is and how
careful the astronomer has to be in
his observations. Indeed. for a long
time. before modern delicately meas
uring instruments were invented. no
stars distance could be found. for
there was seemingly no angle formed.
and thus the old scientists had to as
sumo the star to be at infnity
burg Dispatch.