In Chapter I we saw the Earth hanging in space, like a globe isolated on all sides, and surrounded at vast distances by a multitude of stars.
These fiery orbs are suns like that which illuminates ourselves. They shine by their own light. We know this for a fact, because they are so far off that they could neither be illuminated by the Sun, nor, still more, reflect his rays back upon us: and because, on the other hand, we have been able to measure and analyze their light. Many of these distant suns are simple and isolated; others are double, triple, or multiple; others appear to be the centers of systems analogous to that which gravitates round our own Sun, and of which we form part. But these celestial tribes are situated at such remote distances from us that it is impossible to distinguish all the individuals of each particular family. The most delicate observations have only revealed a few of them. We must content ourselves here with admiring the principals,--the sun-stars,--prodigious globes, flaming torches, scattered profusely through the firmament.
How, then, is one to distinguish them? How can they be readily found and named? There are so many of them!
Do not fear; it is quite a simple matter. In studying the surface of the Earth we make use of geographical maps on which the continents and seas of which it consists are drawn with the utmost care. Each country of our planet is subdivided into states, each of which has its proper name. We shall pursue the same plan in regard to the Heavens, and it will be all the easier since the Great Book of the Firmament is constantly open to our gaze. Our globe, moreover, actually revolves upon itself so that we read the whole in due sequence. Given a clear atmosphere, and a little stimulus to the will from our love of truth and science, and the geography of the Heavens, or "uranography," will soon be as familiar to us as the geography of our terrestrial atom.
On a beautiful summer's night, when we look toward the starry sky, we are at first aware only of a number of shining specks. The stars seem to be scattered almost accidentally through Space; they are so numerous and so close to one another that it would appear rash to attempt to name them separately. Yet some of the brighter ones particularly attract and excite our attention. After a little observation we notice a certain regularity in the arrangement of these distant suns, and take pleasure in drawing imaginary figures round the celestial groups.