CHAPTER VIII.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 removedfrom 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 thoughthere 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 coolalmost 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 yearsspontaneous combustionhas 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 inair, 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 factbiogenesiswas 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 Neptuneit 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.