THE RESOLVABLE NEBULÆ, STAR-CLUSTERS AND GALAXIES.
When we come to consider the nebulæ, and endeavor to learn what part
electricity has to play in the phenomena presented by these singular
objects, we must recollect, in order to give them their due importance,
that they are neither few in number nor uniform in constitution. Of
the nebulæ, Professor Proctor ("Star-Clouds and Star-Mist") says,
"When the depths of the heavens are explored with a powerful
telescope a number of strange cloud-like objects are brought into
view. It is startling to consider that if the eye of man suddenly
acquired the light-gathering power of a large telescope, and if at
the same time all the single stars disappeared, we should see on the
celestial vault a display of the mysterious objects called nebulæ or
star-clouds exceeding in number all the stars which can now be seen
on the darkest night in winter. The whole sky would seem mottled
with these singular objects." As telescopes, with the advances of
constructive art, increased in power, these luminous clouds became
more and more clearly defined, and many of them became resolved into
clusters of stars, galaxies of suns like the Milky Way, of which latter
our solar system is a constituent part, but more distant from us than
the separately visible stars of that galaxy, and each separated from
the relatively adjacent clusters by intervals of space comparable only
with those which separate them from our own system. Of these glorious
star-clusters, says Flammarion, in "The Wonders of the Heavens,"
"In the bosom of infinite space, the unfathomable depth of which we
have tried to comprehend, float rich clusters of stars, each separated
by immense intervals. We shall soon show that all the stars are suns
like ours, shining with their own light, and foci of as many systems
of worlds. Now, the stars are not scattered in all parts of space
at hazard; they are grouped as the members of many families. If
we compared the ocean of the heavens with the ocean of the earth,
we should say that the isles which sprinkle this ocean do not rise
separately in all parts of the sea, but that they are united here and
there in archipelagoes more or less rich.... They are all collected in
tribes, most of which count their members by millions." Says Professor
Nichol, "System on system of majesty unspeakable float through the
fathomless ocean of space. Our galaxy, with splendors that seem
illimitable, is only a unit among unnumbered throngs; we can think
of it, in comparison with creation, but as we were wont to think of
one of its own stars. "Of these glorious star-clusters the same writer
says, "That no one has ever seen them in a telescope of adequate power
without uttering a shout of wonder." These mist-like star-clouds were
successively resolved, nebula by nebula, until science settled into
the belief that with telescopes of adequate power all nebulæ might be
so resolved, and the capacity of telescopes to thus resolve nebulæ
became a test of their power. But spectrum analysis finally entered
the lists with new methods of investigation, and the comparatively
tiny spectroscope at a single leap passed far beyond the utmost
limits of the highest telescopic vision, and at one blow struck the
whole category of nebulæ into two widely different classes,--those
composed of discrete stars grouped like the suns of our own Milky
Way, and exhibiting the characteristic spectra of such bodies, and
those composed of diffused gaseous matter not yet condensed into
suns, and showing the disconnected spectral lines of simple elemental
gases. The line of division was clear, direct, positive, and beyond all
dispute. Yet beyond these two classes further research has disclosed
certain vast nebulæ in which some portions exhibit true solar spectra
more or less modified and others true gaseous spectra, each apparently
merging into the other by gradations so faint and delicate that the
inference is irresistible that in these nebulæ we see the processes
of galactic and solar creation at various stages of their development.
Of these nebulæ, Professor Ball says, "In one of his most remarkable
papers, Sir W. Herschel presents us with a summary of his observations
on the nebulæ, arranged in such a manner as to suggest his theory
of the gradual transmutation of nebulæ into stars. He first shows
us that there are regions in the heavens where a faint diffused
nebulosity is all that can be detected by the telescope. There are
other nebulæ in which a nucleus can be just discerned, others again
in which the nucleus is easily seen, and still others where the
nucleus is a bright star-like point. The transition from an object
of this kind to a nebulous star is very natural, while the nebulous
stars pass into the ordinary stars by a few graduated stages. It
is thus possible to enumerate a series of objects, beginning at one
end with the most diffused nebulosity and ending at the other with
an ordinary fixed star or group of stars. Each object in the series
differs but slightly from the object just before it and just after
it." And of these composite nebulæ, he adds, "The great nebula in
Orion is known to be the most glorious body of its class that the
heavens display. Seen through a powerful telescope, ... the appearance
of this grand 'light stain' is of indescribable glory. It is a vast
volume of bluish gaseous material with hues of infinite softness
and delicacy. Here it presents luminous tracts which glow with an
exquisite blue light; there it graduates off until it is impossible
to say where the nebula ceases and the black sky begins."
With reference to these distant galaxies of apparently complete solar
systems like our own, the same principles must regulate the conversion
of this energy of planetary electricity into the energy of solar
light and heat as we see manifested in our own sun. The light of the
individual stars is sufficient evidence of this; but the question may
be asked, Is the electrical interaction between separate galaxies and
between different solar systems in the same galaxy universal, or are
these operations merely local? In other words, Is the source and the
mode of solar energy in accordance with a single universal law of and
between all created universes, or is it limited in effective energy
to the members of each individual solar system alone? The answer
is, that it is not less universal than the law of gravitation and
no more so. There is a prevalent popular fallacy that the force of
gravity is such that the movements, not only of solar systems, but
of whole galaxies, and of all the illimitable systems of galaxies,
are under its effective control, and that the whole universe of
boundless space acknowledges its overwhelming sway. But nothing can be
further from the truth. We know, of course, that the law is universal,
as expressed in the statement of its terms by Newton, but the mere
statement of the law itself, as applied to interstellar distances,
refutes the idea that solar systems and galaxies can rotate around
any common center by virtue of the attraction of gravitation as a
controlling force. The universality of the law itself has even been
doubted. Professor Ball says, "In the first book about astronomy which
I read in my boyhood there was a glowing description.... I allude to
the discovery, or the alleged discovery, of a certain 'central sun'
about which it was believed or stated that all the bodies in the
universe revolved.... It was too good to be true. No one ever hears
anything about the central sun hypothesis nowadays.... It must be,
then, admitted that when the law of gravitation is spoken of as being
universal, we are using language infinitely more general than the
facts absolutely warrant. At the present moment we only know that
gravitation exists to a very small extent in a certain indefinite
small portion of space. Our knowledge would have to be enormously
increased before we could assert that gravitation was in operation
throughout this very limited region; and even when we have proved
this, we should only have made an infinitesimal advance to a proof
that gravitation is absolutely universal."
Anyone who chooses may prove for himself that the force exercised by
gravitation between the multitudinous suns of our own galaxy, the Milky
Way, and our earth must be quite infinitesimal, and totally unable to
control the motions of our own solar system in a definite orbit through
universal space. We know that the law which regulates the intensity of
light at various distances is the same as the law of gravity,--that
is to say, the proportion is directly as the mass and inversely as
the square of the distance. We know also that the stars which compose
the Milky Way are similarly constituted, generally considered, to our
own sun, and that under similar circumstances the emission of light,
roughly speaking, will vary according to the magnitude of these distant
suns. Now, if any one will stand, at the darkest hour of the night,
when the moon is absent and the sky perfectly cloudless, when the
"Stars that oversprinkle all the heavens seem to twinkle
With a crystalline delight,"
and sweep with his gaze all the concave hemisphere of the sky, and
then compare the light which is radiated around him with the gorgeous
effulgence of the noonday summer sun, he can pretty closely compare
the relative attraction of gravity which all those distant suns
together can exercise upon our earth with that of our own sun. Under
control of the latter, the earth sweeps around in her orbit at the
rate of about twenty miles per second; all these suns could not give
our solar system even a minute fraction of that. Of this starlight
Professor Ball says, "The sun certainly must receive some heat by
the radiation from the stars; but this is quite infinitesimal in
comparison with his own stupendous radiation." Any such attraction,
of course, could not control the motions of our solar system, and
much less that of many of the others.
"The night has a thousand eyes, and the day but one,
But the light of the whole world dies when the day is done."
We can also demonstrate the fact mathematically by an exceedingly
rough calculation, which, however, will be sufficient for our
purpose. Of the Milky Way, which comprises only the stars of our own
sidereal system, Professor Ball says, "One hundred million stars are
presumed to be disposed in a flat circular layer of such dimensions
that a ray of light would require thirty thousand years to traverse
one diameter." (The most recent estimates make the number of the
stars which compose the Milky Way several times one hundred million,
occupying a correspondingly greater amplitude of space. The number in
any case is sufficiently stupendous.) Our solar system is located in
space at the apex of a vast transverse cleft, and nearly at the center
of this disk. Let us leave out of consideration the lower half of the
Milky Way, as we look upward on a starlit night, and conceive this
galaxy to extend only across the midnight sky above us like an archway,
with fifty million suns, visible and invisible, exposed in the field
of our vision. The nearest of all the fixed stars to us is that known
as Alpha Centauri,--not visible, however, in our northern skies. This
star is about two hundred and thirty thousand times as far from our
sun as is the earth. If of the same mass as our sun, it must exert
upon us an attractive force of gravity one fifty-three-billionth
that of our own sun. Next in distance is the star No. 61 of the
constellation Cygnus. This may be three times as distant, and is
certainly not less than twice. The light of the former will reach
the earth in three and one-quarter years; that of the latter in not
less than six and one-half years, perhaps much more. These are our
nearest stellar neighbors. While the former will attract us with only
one fifty-three-thousand-millionth that of the sun, the latter will
attract us with less than one two-hundred-thousand-millionth that of
our sun. Conceive, then, a square pyramid extending radially upward
for three thousand times the mean of these distances to the upper
probable limits of the Milky Way, a light-distance of fifteen thousand
years, and that this pyramid expands according to the squares of its
distances, so that it will contain within it, equally distributed,
all the stars (fifty million) of the upper half of the disk of the
Milky Way; the sum total of all these attractions could not reach one
twenty-millionth part of that of our sun upon the earth. If we continue
to pile galaxies, in the same perpetual recession, behind each other
to all infinity, we still could not engender sufficient attractive
force to control the observed movements of the multitudinous stars of
space. The very statement of the law of gravitation itself disproves
it; for if we multiply orbs and systems according to any principle
of aggregation that we know of in the way of distribution of such
systems, or anything possible, with due regard to their own mutually
interacting movements in space, we could never reach the inside limits
of such a sphere of control, because the piling up of orb behind orb
adds but an infinitesimal fraction to the force of gravity, for as
the orbs themselves multiply in distance progressively by hundreds,
their relative attractions inversely diminish by ten thousands. No
possible increase of suns directly in mass could compensate for such
an inverse ratio of squares, even if all intergalactic space were
peopled with suns, instead of being, in fact, like a vast ocean, with
a few small clusters of islands scattered here and there throughout
its illimitable extent.
Of these vast realms of space, Professor Ball asks, "Is our sidereal
system to be regarded as an oceanic island in space, or is it in
such connection with the systems in other parts of space as might
lead us to infer that the various systems had a common character? The
evidence seems to show that the stars in our system are probably not
permanently associated together, but that in the course of time some
stars enter our system and other stars leave it, in such manner
as to suggest that the bodies visible to us are fairly typical
of the general contents of the universe. The strongest evidence
that can be presented on this subject is met with in the peculiar
circumstances of one particular star. The star in question is known
as No. 1830 of Groombridge's catalogue. It is a small star, not to be
seen without the aid of a telescope.... We shall probably be quite
correct in assuming that the distance is not less than two hundred
billions of miles.... The velocity is no less than two hundred miles
per second.... The star sweeps along through our system with this
stupendous velocity.... The velocity being over twenty-five miles a
second, the attraction can never overcome the velocity, so that the
star seems destined to escape." Of the star Alcyone he says, "Doubtless
that star is thousands of billions of miles from the earth; doubtless
the light from it requires thousands of years--and some astronomers
have said millions of years--to span the abyss which intervenes
between our globe and those distant regions." And yet these stars,
these galaxies, and even all the nebulæ we see or ever shall see, are
merely in the vestibule of space; we have scarcely even yet lifted the
outer curtain at the entrance of those vast realms. That the popular,
but pseudo-scientific, idea of a series of ever-widening concentric
orbits, increasing at every new expansion by an inconceivable ratio,
is incredible we can well understand, and it is a satisfaction to
know that such a wild hypothesis finds no warrant in the dicta or the
demonstrations of science. And it is in the failure of gravity to
control over the intervening space which lies between those vastly
distant centers that we may hope to find the inklings of a more
far-reaching law, by which nebulæ like that of Orion crystallize out
into separate star systems, just as in the rocks, whether igneous,
metamorphic, or sedimentary, we find the attraction of cohesion yield
to that of crystallization, until the whole cleft rock blazes with
countless garnets in the schist and quartz crystals in the gneiss,
or reveals the yellow specks of olivine in volcanic ejections.
We shall find in the processes concerned with the development of living
things the workings of a similar great law, perhaps the same. Wherever
there is the possibility of life, there we find life. There seems to
be an all-pervading vital tension, so to speak, an energizing force,
which drives the evolution and ascent of life forward and upward by
successive leaps, as it were, from type to type, from race to race,
and even from nation to nation. In this universal forward movement
we may dimly discern the primordial creative and developing impulse,
constantly acting, but manifesting visible change only at intervals
as gathering forces accumulate and equilibrium is disturbed. It
manifests itself in all the fields of nature,--vital, chemical,
molecular, molar, systemic. It is the ever-acting, eternal past,
present, and future, the macrocosm and the microcosm, the panurgus,
the Brahma, the Ancient of Days, and cannot be silenced or evaded:
"They reckon ill who leave me out,
When me they fly I am the wings."
R. Kalley Miller, in his "Romance of Astronomy," says, "It would be
hopeless to attempt expressing in ordinary language the vast distance
at which these clusters of stars are situated from us. If we were to
reckon it in miles, or even in millions of miles, figures would pile
upon figures till in their number all definite idea of their value
was lost. We must choose another unit to measure these infinitudes of
space,--a unit compared with which the dimensions of our own solar
system shrink into absolute nothingness. The velocity of light is
such that it would flash fifteen times from pole to pole of our earth
between two beats of the pendulum. It bridges the huge chasm that
separates us from the sun in little more than eight minutes. But the
light that shows us these faint star-clusters has been travelling
with this frightful velocity for more than two million years since
it left its distant source. We see them to-day in the fields of our
telescopes, not as they are now, but as they were countless ages before
the creation of man upon the earth. What they are now who can tell?"
The movements of solar systems through space are unquestionably
controlled by some wider law than that of gravitation, and it still
remains for science to seek its hidden principles and discover its
mode of operation. We know that some stars travel alone, like the
star already noted, No. 1830 of Groombridge's catalogue; that others
travel in pairs, like the double star Mizar and its companion Alcor;
and others in groups, like the stars Beta, Gamma, Delta, Epsilon and
Zeta, of the constellation Ursa Major; that we are driving towards
the constellation Lyra and leaving behind us Sirius and its fellows,
and that many, if not all, of the stars whose motions we can measure
have a rapid movement through space, but under what control, in accord
with what hidden harmony, and under what general plan they move,
we do not know; but the laws of electrical action of the circling
planets upon their central suns, and of these upon space, we can
readily account for by the similar operation of the same laws within
our own solar domain; and we know by the similar terms of the ratio
of distribution of light that this is commensurate in extent with the
law of gravity, and operates in a like proportion of energy over all
intervening distances; so that wherever our sun presents a visible
point of light, there it is pouring its energy into space, and every
sun we can see, every galaxy, every star-cluster, nay, every nebula,
is likewise pouring into the interplanetary space of our own solar
system its proportionate quota of energy. The very fact that we can
see the star shine is itself the fullest evidence that this is so,
and evidence also that the law of gravitation there, too, is still
in force, operating over these same distances, and with the same
proportionate energy.
Knowing all this, we can read with a new light the grand vistas
of the skies, with their starry denizens, and claim them all as
parts of our own family; and the mutual interchange of attractive
energy and of light and heat will not fail between us until those
inconceivable distances shall have been reached which human knowledge
can never span and where speculation fails; and even there, from out
those dark abysses,--dark to our human eyes,--the call will still
faintly reach us, and our response will reach them also, though we
shall never have tangible evidence that such mutual ties continue to
exist. Industriously our planets gather their mighty energies from
the surrounding springs of space, as one dips water from a crystal
stream; we hand it over to our sun, and he, the royal high-priest,
sprinkles it in glittering diamond-sprays over all those countless
suns and their subject worlds, and they are baptized with an eternal
baptism into our common brotherhood and we into theirs. Our familiar
planets, Mars, Jupiter, Neptune, the earth, and even our little moon,
seem to raise their voices and take actual part in the councils of
almighty power, to move about as perpetual benefactors, gathering and
spreading beneficence abroad, instead of cowering, a hapless few,
like storm-stayed travellers, around the dying embers of our poor
old sun, passive recipients of the light and heat and life which we
have been taught to believe are slowly sinking into ashes and fading
away in eternal darkness and death. One swift glance into these
boundless truths is better for the human soul than the slow passage
of whole hopeless centuries, which leave as their inevitable legacy
on earth a vast and final catastrophe, in which everything that gave
us light and heat and being must perish forever. Has it, indeed,
come to this, that the last word which science has to offer is,
"After us the deluge"? By no means. We have merely been endeavoring
to measure the right hand of God by weighing and measuring a single
isolated one of his countless multitude of suns.
It is as though one standing beside a great water-wheel should estimate
its power and rotation by measuring the width and depth of the buckets
and calculating the weight of water which its thirty-two receptacles
contain, saying, "at its present rate in so many seconds it will cease
to move." But we take him to the water-gate, and show it wide open;
to the great dam above it which contains cubic miles of water; and
still beyond that to the mighty fountains bursting forth with their
rush and roar from the rock-ribbed fastnesses of the eternal hills,
and pouring their unfailing flood-tide down forever and ever. And we
do not pause even here: we show him the vapors rising from the spent
water again, condensing into clouds, pouring down in torrents of rain
among the hills, and that these continuously feed the sources of the
fountains, which in turn supply the wheel almost to bursting. And so
it is with the glorious mechanism of the heavens.
The source of solar energy is not to be found in the sun itself,
but in his environment; and he himself, in all his glory, is but the
king, crowned with gold, blazing with rich apparel, and scattering
benefits among his satellites, not from his own private treasury,
but who himself is enriched by the mighty tribute with which his
willing subjects continually endow him, and to whom alone he owes
all his pride and power and wealth and magnificence, and which he, in
turn, so freely expends, transmuted in form alone, in the perpetual
improvement and welfare of his domain. He is the faithful ruler,
but not the creator; the beneficent monarch, but not the god.