NEBULAE.
We are told by Prof. Ball that such is the translucency of nebulae
one might think to be able to see through them the stars lying in
the back-ground, were they in the right position for observation. If
nebulae are thus translucent it does not seem possible that they can
be composed of the same materials as the planets of the solar system,
whose densities are generally so great. For were the whole of earth’s
substance spread out to one-hundredth of an inch in thickness we can
not believe it would be sufficiently clear to allow light to penetrate
it to any great extent, as earth has a density that leads one to think
it is centrally composed almost—if not wholly—of iron, lead, gold,
or like weighty elements that seemingly would never be transparent
however highly heated and expanded. But if the nebulae are similar to
the planets in their substances they must then consist of enormous
masses of luminous, heated matter in a highly diffused state, in order
to be perceptible to us at so great a distance; and how can they be
translucent if the coloring matter is retained to darken the gases
that are in combustion? Material similar to that of earth, if highly
diffused and placed in an element 300° below zero, would cool almost
immediately; and whether luminous or not would be likely to obstruct
our view of all stars lying behind it.
We are told again by the same writer that doubtless there are hundreds,
thousands, or even millions of dark bodies to each luminous one in
space. But it has not been shown that these dark bodies ever needed to
have been luminous in their formation, neither is it improbable that
non-luminous matter,—even if once highly diffused, and spread out in
the heavens as our sun is supposed once to have been diffused,—should
have formed into these dark, spherical bodies in some manner similar to
the condensation of vapor into clouds. If this be true the presumption
is that the dark bodies are hiding many bright stars from our sight.
It is not possible, then, to conceive that the many stars thus
hidden—or partially hidden—may, like our sun when totally eclipsed,
give a corona-like glow? Our own sun’s corona flames out in every
direction for more than 200 thousand miles, and should there be many
suns eclipsed by the dark bodies in space might they not likewise, in
some instances, present a nebulous appearance with a startling coronal
effect? Theta Orionis, the wondrous multiple star, seemingly lying
in Orion’s great nebula, is regarded as belonging to it because of
its being in the same degree of the heavens; but although in the same
degree it may be in quite a different plane, as light travels at the
rate of over eleven millions of miles per minute. If this nebula is
unresolvable stars then the light from it may be millions of years in
reaching us, while from Theta Orionis, if it lies in the foreground,
the light might reach us possibly in one hundred years,—according
to the distance it is removed from earth. The probabilities are
that the multiple star lies nearest the earth, for if the nebula is
composed of material similar to earth, we could not think at such a
distance to be able to see through a single foot, or even inch, of its
substance. There are about 5,000 stars visible to the naked eye in
both the northern and southern hemispheres, but only about one-third
of that number are visible at any one time. Few people are able to
see two thousand of them on the clearest night, while many do not see
one thousand, because of their inability to detect those of the sixth
magnitude. The Milky-Way, therefore, is quite like a great nebula to
man’s unaided vision. At each increase of photographic and telescopic
power new stars are observed, until it is now said that 100 millions
may be visible by their aid. If all these knowable stars are no more
to space than a drop of water is to the Atlantic ocean, as the above
writer has said, it is not in the least surprising that we see a
great number of nebulae. This we must ever expect, even though our
telescopes be increased a millionfold in power. In fact it would be
most surprising if unresolvable nebulae did not forever appear in space
as often as instruments of increasing penetration should be brought
into positions to examine them. If space, like our oceans and our
atmosphere, should be subordinate to something greater that we have
never seen, and have no prospect of seeing in our present state, we can
form concerning it no adequate conception.
To obtain an impression of the greatness of the nebulae in the heavens
let us discord every instrument as though there were none, and upon
some clear, moonless night stand gazing into the starry heavens. It
might seem as though we were looking at millions of stars, but we
should find by counting that the distinct points of light were only
about one thousand. Imagine our sight to increase so that we beheld two
thousand stars, then four thousand, eight thousand, and so on until
finally, with our sight increased a thousand-fold, we were able to see
one hundred millions of stars, the number that may be seen with the
most powerful instruments. What we beheld as nebulae when we saw but
one thousand distinct stars would thus be resolved into shining suns
with sufficient increase of power. Then is it not a fair supposition
that—if our sight were adapted to the beholding—we should be able to
detect not only one hundred millions of stars, but myriads of them?
Again, when we think of the irregular shapes that many of the nebulae
have, can we believe that they are rotating like the sun and planets?
for we look to spherical bodies for revolution. We know there are
many peculiar-shaped nebulae emitting light and heat, yet that light
and heat may in nowise be produced by their swift revolutions, and we
cannot think of them as undergoing a change such as we would expect
from the nebular theory of world-formation.
In reference to the nebula in the Sword’s-handle of Orion, which
contains matter sufficient to form two thousand and two hundred
trillions of suns like our own; if this matter is of any density—or if
not, even—it would seemingly cool almost instantly in an element 300°
below zero. In truth how could it have become heated unless composed
of some combustible element, like hydrogen, that would spring of
itself into a mass of flame with an energy,—if there is conservation
of energy,—that would exist for ever, and might repeat its work over
and over again as do the oceans of our earth? There is no evidence,
as far as we have ascertained, that this nebula rotates; nor can we
believe that its luminosity is caused by swift revolution when our own
sun, less than one million of miles in diameter, rotates but once in
twenty-five days and is now moving swifter, according to the laws of
mechanics appertaining to spherical, vaporous bodies, than ever before.
Even scientists and philosophers cannot tell us of the formation of a
grass-seed, from which springs life identical with its kind; neither
can they detect with the best microscope any difference between the
varied forms of matter in the first stages of inception, nor feel sure
whether there will be developed therefrom a tree, a dog, an elephant,
or a man. For two hundred years _spontaneous combustion_ has been
discussed, some finding from an infusion of hay that life appeared;
but when the idea was supposed to have been proved it was discovered
that life was in _air_, and with the life-germs taken from it no
spontaneous generation would arise. Later it was found that bacteriae
would exist in great heat, and from that fact _biogenesis_ was thought
proved; for life only could come from life. We remember also that for
years the famous Bodes Law was considered fully established, until
upon the discovery of planet Neptune it was found to be so far out of
position that the law was no longer applicable to the distribution of
the planets of the solar system. Remembering all these changes after
science considered the theories well established, we believe there are
things to-day about nebulae, even, that conflict with the hypothesis
under consideration; as, for instance the irregular shape they often
assume, and the fact that many have already been resolved into stars
with the aid of sufficiently powerful instruments.
[Illustration: Decoration]