Universe still in Evolution
The question may be considered from another point of view. On searching the heavens we find that many of the stages which are assumed in Laplace’s hypothesis are still represented by actual existences. There are, to begin with, those immense diffused nebulæ, almost incapable of definition, which are proved, on spectroscopic examination, to emit that kind of light which is characteristic of glowing gas; from these we pass to others which are resolvable by the telescope into a central and more condensed nucleus, with two mighty nebulous arms whirled round in a spiral, and bearing more condensed masses in their midst; even ring nebulæ are known to exist; and, finally, there are nebulous halos which surround some of the stars. Then we come to the stars themselves, which are suns of various degrees of magnitude, some immensely larger than our own luminary, and these are evidently in various stages of existence. Some are blue, and afford evidence of a higher temperature than that of our sun; others are yellow, and make a nearer approach to the solar temperature; while, again, others are red, and certainly colder.
These, in conjunction with other considerations, lead to the conviction that the universe is in a state of evolution, and that the solar system at one time existed in a nebular state. But whether Laplace’s description of the series of events through which the original nebula passed is the true one or not is a very different matter; it presents so many difficulties that scarcely any student now supports it.
In the beginning, it is supposed that the earth was part of a vast nebula of gaseous matter and meteorites, resembling the nebula of Argo, illustrated above.
Later, as the cooling process advanced, the nebula assumed a rotatory movement in the form of a spiral. The nebula of Andromeda affords an excellent illustration of this.
Another stage would be as in the annular nebula of Aquaris, the mass forming into a ball with the outer ring attached.
