The Pacific commercial advertiser. [volume] (Honolulu, Hawaiian Islands) 1885-1921, 1899-09-19
A TRIPLE SYSTEM
Not a Single North Star
as Supposed.
important Discovery al Lick Obser-
Vatory on the Part PLAYED by Po-
1ar!s In Solar System.

LICK OBSERVATORY, Sept. g.
Director Keller today gave out the fol-
| lowing statement in reference to the
part played by Polaris, popularity
| known as the North Star, in the move
ments of bodies through the heavens
"A discovery of much scientific and
| considerable popular interest has just
! been made by Professor Campbell with
| the great telescope of the Lick Obser-
vatory. 1t is that Polaris, or the North
| Star, doubtless the best-known star in
the whole armament, is really triple
system. Two of the bodies in this sys-
| tenn revolve around each other in a
| period of four days, and at the same
time move in a much wider sweep
| around a third body, in much the same
way as the earth and moon do around
the sun.
The separate bodies which compose
the system cannot be seen with the
telescope, nor is it likely that thew
ever Will be seen with any instrument
Their existence is demonstrated by
observations made with a spectroscope.
By method, which need not be ex-
planned here, the speed with which a
heavenly body is moving toward or
away from the earth can be measured
with spectrOscOpe attached to a tel
escope. The method has been known
for many years, but it is only recently
that the necessary accuracy for OBJ
servatiOnS of stars has been reached.
by the application of photography.
There are various ways of checking
of
as the sun turns on it's axis, one edge
IS constantly approaching the earth,
and the other is receding from it. at
the rate of about one and a quarter
miles per second; the spectrOscOpe is
round to measure this motion correct
ly. Again, the velocity with which
the planets are moving in the line of
sight can be calculated from the known
dimensions Of the solar system. and
IN this case also the reliability OF the
spectroscopic method has been proved.
observations of stars by this method
are now being made at a number of
the leading ObservatOries of the world.
According to the laws of motion, a
BODY once set in notion and left to it
self, will move on forever, in a |
straight line, with uniform velocity
ANY change whatever in it's motion in
dlcates the existence of a disturbing
force. The great majority of the stars
are found to move with unchanging
velocity, but in a small number of |
cases the velocity varies, and these
are OF great interest to the astronomer |
A star may, Of course, move across the
line OF sight, as we'll as in it. but of |
the former motion the spectroscope
takes no account
Inc existence Of a revolving Svs-
tenn was proved by this method in the
case of the famous variable star Algol.
1t had long been assumed that the
changes in the light of this star are
due to eclipses by a dark companion.
and the correctness of the hypothesis
was proved by Professor Vogel of Ger
many in 1899
quite number of similar cases are
now known, fourteen of which. includ-
ing the brilliant binary star Capella.
nave been discovered at the Lick OBJ
servatory. Polaris is now, however. the
most interesting of these The velocity
changes in a period of three days,
tWenty-three hours by about six kilo-
meters, or nearly four miles per sec
ond. The longer period of change has
not as yet been determined: it NAV
amount to several years. 1t may be
some time before this discovery is
verified at other ObServatOrieS as the
high degree of accuracy to measure.
With certainty, so small a change of
motion has as yet been reached only
at Mount Hamilton"