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Page 60
When g Virginis was observed in 1718 by Bradley, the component
parts were 7" asunder. He incidentally remarked in his note-book
that the line of their connection was parallel to the line of the
two stars Spica, or a and d Virginis. By 1840 they were not more
than 1" apart, and the line of their connection greatly changed.
The appearance of the star is given in Fig. 75 (15), commencing
at the left, for the years 1837 '38 '39 '40 '45 '50 '60 and '79.
also a conjectural [Page 213] orbit, placed obliquely, and the
position of the stars at the times mentioned, commencing at the top.
The time of its complete revolution is one hundred and fifty years.
[Illustration: Fig. 75.--Aspects and Revolution of Double Stars.]
The meaning of these double stars is that two or more suns revolve
about their centre of gravity, as the moon and earth about their
centre. If they have planets, as doubtless they have, the movement
is no more complicated than the planets we call satellites of Saturn
revolving about their central body, and also about the sun. Kindle
Saturn and Jupiter to a blaze, or let out their possible light, and
our system would appear a triple star in the distance. Doubtless,
in the far past, before these giant planets were cooled, it so
appeared.
We find some stars double, others triple, quadruple, octuple, and
multiple. It is an extension of the same principles that govern
our system. Some of these suns are so far asunder that they can
swing their Neptunes between them, with less perturbation than
Uranus and Neptune have in ours. Light all our planets, and there
would be a multiple star with more or less suns seen,
[Page 214]
according to the power of the instrument. Perhaps the octuple star
s in Orion differs in no respect from our system, except in the
size and distance of its separate bodies, and less cooling, either
from being younger, or from the larger bodies cooling more slowly.
Suns are of all ages. Infinite variety fills the sky. It is as
preposterous to expect that every system or world should have analogous
circumstances to ours at the present time, as to insist that every
member of a family should be of the same age, and in the same state
of development. There are worlds that have not yet reached the
conditions of habitability by men, and worlds that have passed
these conditions long since. Let them go. There are enough left,
and an infinite number in the course of preparation. Some are fine
and lasting enough to be eternal mansions.
_Colored Stars._
In the cloudy morning we get only red light, but the sun is white.
So Aldebaran and Betelguese may be girt by vapors, that only the
strong red rays can pass. Again, an iron moderately heated gives
out dull red light; becoming hotter, it emits white light. Sirius,
Regulus, Vega, and Spica may be white from greater intensity of
vibration. Procyon, Capella, and Polaris are yellow from less intensity
of vibration. Again, burn salt in a white flame, and it turns to
yellow; mix alcohol and boracic acid, ignite them, and a beautiful
green flame results; alcohol and nitrate of strontia give red flame;
alcohol and nitrate of barytes give yellow flame. So the composition
of a sun, or the special development of anyone substance thereof
at any time, may determine the color of a star.
[Page 215]
The special glory of color in the stars is seen in the marked contrasts
presented in the double and multiple stars. The larger star is
usually white, still in the intensity of heat and vibration; the
others, smaller, are somewhat cooled off, and hence present colors
lower down the scale of vibration, as green, yellow, orange, and
even red.
That stars should change color is most natural. Many causes would
produce this effect. The ancients said Sirius was red. It is now
white. The change that would most naturally follow mere age and
cooling would be from white, through various colors, to red. We are
charmed with the variegated flowers of our gardens of earth, but
he who makes the fields blush with flowers under the warm kisses of
the sun has planted his wider gardens of space with colored stars.
"The rainbow flowers of the footstool, and the starry flowers of
the throne," proclaim one being as the author of them all.
_Clusters of Stars._
From double and multiple we naturally come to groups and clusters.
Allusion has been made to the Hyades, Pleiades, etc. Everyone has
noticed the Milky Way. It seems like two irregular streams of compacted
stars. It is not supposed that they are necessarily nearer together
than the stars in the sparse regions about the pole. But the 18,000,000
suns belonging to our system are arranged within a space represented
by a flattened disk. If one hundred lights, three inches apart,
are arranged on a hoop ten feet in diameter, they would be in a
circle. Add a thousand or two more the same distance apart, filling
up the centre, and [Page 216] extending a few inches on each side of
the inner plane of the hoop: an eye in the centre, looking out
toward the edge, would see a milky way of lights; looking out toward
the sides or poles, would see comparatively few. It would seem as if
this oblate spheroidal arrangement was the result of a revolution of
all the suns composing the system. Jupiter and earth are flattened
at the poles for the same reason.
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