The morning call. [volume] (San Francisco [Calif.]) 1878-1895, 1891-05-31
THE BEAUTIES OF
ASTRONOMY.
WHAT'S Known Of the Eighty Million Stars
Seen Through a Telescope.
New Stars That Have Been Discovered By
Means Of the Improved Telescopes = Some
Things That Have Been Made Clear


Means of the Improved Telescopes = Some
Things That Have Been Made Clear.
By the increased power of telescopes the
number of stars within our ken has been in
creased from 6OO0 the number which may
be seen in both hemispheres by the naked
eye, to probably about 100000 The star
nearest to the earth, Centauri is about
275.000 times as far from us as the sun is.
and Sirius is about twice as far away as
that; if, however, we could view these
bodies at an equal distance. a Centauri
would appear nearly twice as bright as our
sun, and Sirius forty times as bright
Further, we know that ali these bodies,
although they are called fixed stars in as
trOnOmy books, so far from being fixed are
all in rapid movement, and the rate in some
cases fills us with establishment. Thus, one
star $3.50 GrOombridge) has a velocity Of
not less that 200 miles a second. This would
carry it from New York to ConstantinOple
in about a minute, and from the earth to
the sun in five days Another (61 CygnD
has velocity of not less than 30 miles
second, or 100000 miles day SO far,
IhOts VIC HIlH AiCtb b4lO oSdlo dAO az u'lASA CIV
distances, that they are of different sizes,
and that instead of being fixed they are all
in movement
We now come to another question. Why
do these bodies, whether near or distant,
give out light? They give out light be-
cause they are hOt, and some Of them are
hotter than almost anything we can
imagine. But we are not left to our imsgi-
nation. By the use of the prism the ehild's
wonder as to what the stars may be has
been changed into a certain knowledge Of
what stars Ike the sun really are. Such
bodies are masses OF glowing gas the ma
teTlalS OF which are for the most part pre-
ciSely the same as those Of which our earth
is bullt up; the great difference between
such stars and the earth at the present time
being that they are hot while the earth is
cold.
All the metals, or nearly all of them.
which we read OF in books Of chemistry,
have been found il the sun; and it is quite
possible that some of the nOn-metals may
exist in part Of the sun which we cannot
get at by
OUR METHODS OF WORK.
However this may be, we may be sure
that the nOu-metaS will be in the sun some
day, and that. when the sun is as cool as
the earth, its chemical composition viii re-
semble our own essentially.
The sun is so hot at present that its outer
atmosphere, instead of being composed of
cool oxygen and nitrogen and water vapnr, as
happens with our own, consists Of brightly
shining hydrogen gas ana iron vapOr chiefly.
The iron is not solid, and it IS not molten,
but exists as iron steam, at perhaps, dis
tance of 100000 miles above the shining orb
that we see and call the sun. This, | think,
may be taken as a fair indication that the
sun is, indeed, very hot body, especially
when we remember that as its center is APP
preached the temperature must always in
crease.
l have said this much about the sun be-
cause it is very natural to ask whether all
stars are like the sun. 1t used to be thought
that they were, but for one do not think
this IS so. When we come to examine the
bodies which shine in the sky those aim
patches OF gray light called nebul8 as well
as many of the stars themselves the prism
tells us that the light which they send to us
Is very different from the light sent to us by
the sun, and by other stars, the light Of
which is exactly like sunlight.
1t is fair to suppose that if the light sent
out is different the body which sends it out
must also be different in some way or an
other. A great deal of work recently done
shows that probably many stars, instead of
being Ike the sun, are built up as the comets
are, OF enormous clouds or swarms OF little
bodies, some of them. perhaps, no bigger
than grains Of dust, the different quantities
and qualities OF the light given out depend
ing upon the motions Of these little particles
and the average distance between them. So
when We have great many of these little
masses closely packed together and moving
rapidly, they viii have an opportunity to
strike one another and thus produce light
and heat In a greater degree than can hap
pen in those other s0-called stars" where
the dust is Sparser and
THE MOTION LESS RAPID.
This is an idea which has lately been sug-
gested, and | refer to it here because it APP
pears to make clear great many points on
which children even of a larger growth have
been long puzzled. The idea, in its most
general form, Is that the bodies which
shine in space. whether nebuse. comets,
stars, planets or moons, all start in the same
way. For the starting point, it is imagined
that they all consist Of the little particles TO
which l have referred, far apart, and not in
very rapid movement. Collisions take place
between these particles, and give rise to
light as the striking Of flint against a steel
gives rise to light. The light at first is dim,
because the collisions are not numerous,
but in time the little particles cOndense to-
ward center, which, therefore, becomes
brighter because the PARTICLES are then
nearer together, clashing together Oftener,
and, therefore, developing larger amount
of heat and light.
In this way we pass from what we see in
the heavens as patches of milk-white light
called nebulSe to other bodies even hotter
than our sun, and when the stage is reached
in which we see Specks OF light merely and
deal with stars properly so called we get
q hot body. which Increases in temperature
as all the little particles arrive at the CENTER
until the motion Of all of them has been
changed into heat, and a ball of YapOr re-
suits, very, very hot.
AS soon as the supply of heat ceases the
mass begins to cool. Our sun is such a cool
ing mass. The cooling goes on until at last
body such as our own earth is formed.
This is why it is that the chemical compost
ton OF the sun and earth are so similar
If this is what really happens, we can
easily explain the colorS of all the stars.
Each stage OF heat in a star has its own
special color. 1t is true that sometimes
very nearly the same color is produced at
two different stages of heat but apart from
this we know that very white stars are at
the condition Of greatest heat, and that
yellow stars are cooler, though some are
old, some young; and that very red, but
especially blOOd-red stars, are lettering on
the verge OF inyl5ibilty, having run
THROUGH ALL THEIR CHANGES.
So far we have considered that the GUAM
tity of light given out by a star depends
upon its age, so to speak But this is not
all. In some cases stars, although We do
not see them as double stars, are really
double, and this causes them to vary their
light. We may imagine one swarm of
coIiding and light-giying bodies going
round another; and if The Swarms are not
always the same distance apart, and there
Is SOou ItdSOu WHY lucy SHOuiu not De, JOeY
will at times, so to speak, intermingle, and
then there will be more opportunity for
clashingS and, therefore more light viii be
given out. The star will be what is called
a variable star" and the waxing and
waning of the light will be regular, if we
are dealing with two swarmS only, or
irregular, if we are dealing with more.
Not only so, the two swarmS which cou-
sisted of separate PAL tiees in the FIRST in
stance will eventually become bodies like
the sun, aud go on until both have become
cooling bodies, one of them, perhaps, cooler
than the other. Then it may happen that
the cooler body will come between our earth
and the brighter one and stop some of its
light in the same way that our moon stops