The suburban citizen., 1901-07-27
MARVELS OF ASTRONOMY
WONDERFUL DISCOVERY OF PLAN.
ETS REVOLVING AROUND STARS.

Send Us - The Utility of the Spectre
scope - brightness and Distance Of
Stars collisions In the sky.
No achievement of the human. intel
lect is more wonderful than the dis
coyery of planets revolving around
many of the stars writes Professor
Simon Newcomb, LID. II these
bodies could be seen with a telescope
there would be nothing wonderful in
their being found. But they are gem
orally, so far as we know, entirely
dark-at least they send forth no light
that the human eye could discern in
the most powerful telescope. They
are, and must forever be invisible.
How, then, is their existence made
known2 BY their attraction on the
stars around which they revolve, and
which they cause to swing first to
one side and then to the other. But
this swing of a star is so small as to
be entirely beyond the power OF de-
lection by the most delicate eye and
the most powerful telescope. TO all
appearances the stars remain abso-
lutely at rest, except for the slow,
straightforward motion which we find
many OF them to have when observa-
tions on their positions are extended
through years or generations. If we
cannot see any motion, how do we
know that the stars mover
This is the real wonder. 1t is done
by analyzlng the light which the star
sends to us. 1t has long been known
that light really consists in minute vi
brations or wavelike motions in an
ether which fills all space. There are
from 10000 to 100000 of these waves
in the length Of a single inch, and yet
they travel forward so rapidly that
they would encircle the earth seven
times between the two beats of the
clock. Small though they are, each lit
tie wave has its crest, as have the bill
lows Of the ocean. On the latter the
distances between two successive
crests may be more than the length Of
a ship or less than that Of n ships
boat So is it with light. Although
countless millions Of millions Of waves
pass in a single second, some vibrate
more rapidly than others.
BY the aid Of the spectroscOpe the
astronomer analyses the light Of a
star, and thus finds the length OF GER
tain of the waves which it sends to-
ward us. If it is moving in our direc-
ton these waves will be little short
er than when it is moving away from
us. And thus it is said that, by meas
uring the length of the light-wave
which a star emits, it can be determ-
ined whether the star is increasing or
diminishing it's distance from us.
When these most delicate and difficult
measures were made upon number
of the brighter stars, it was found that
some of them changed their motion to
or from us. For a few hours, or per-
haps few days, a star would be NOV
ing toward us, then il would slacken
its pace and move away from us, TO
return toward us again. Thus it would
vibrate backward and forward, as 1t
were, like a swinging pendulum. AS
matter of fact, we know that the
motion was more likely to be around
and around in a circle But this circle,
though millions Of miles in extent is
so small as to be quite invisible at the
enormous distances of the fixed stars.
The motion of the stars which |
have des 'rlbed, being made known by
the light, can be as well determined
upon star at the most immeasurable
distance as upon one in our immediate
neighborhood. And thus it is that
these motions are made out when the
telescope fails to show any movement
whatever. They can be caused only
by the attraction of invisible, but
massive, bodies revolving around the
stars as the planets revolve around
the sun. SO exact have these measures
been made in recent times that the
form of the orbit Of a dark body can,
in some cases, be calculated with
more or less exactness. And thus 1t
happens that, if there are any inhabi-
tants on these planets, our astronom-
ers here on earth could tell them more
about the motion Of the world on
which they live than the most civil
lied people a few centuries ago knew
of the motions of the earth on which
we dwell.
The most recent researches show
that there is an immense variety
among the stars, especially as to their
actual brightness. OF course Il star
of any given brightness will look faint
er the farther 1t is from US Thus it
was In former times, supposed that the
brightest stars were most near us But
this is not always the case. 1t is
true that Sirius, the brightest star in
the heavens, is among the nearer ones,
about twice as far as the nearest star
known. But the next brightest is
Canopus, which never rises in our
northern attitudes, though it may
sometimes be seen in the Gulf States.
1t is there visible low down near the
southern horizon some time during the
winter evenings. Gill, at the Cape of
Good Hope, made long series Of the
most exact measures on the position