The durations of the movements of the planets are immense. The variations presented in the periods of the stars occur by thousands of centuries. It takes light millions of years to cross the distances that separate the stars from one another. What can be said of the immensity of those worlds as compared with which the earth is but an atom, of the prodigious multitude of the suns of space, more numerous than the grains of sand at the bottom of the sea, and of those velocities with which all the stars are carried in immense whirls across the infinite?
But you tell me astronomy is a perfect science; it has reached the height of knowledge, and there is nothing left in it for the amateur. I answer that there is always something to be reaped in the astronomical field of investigation for both the learned and the modest amateur. How many times has it not been said that all was known; and then, as the power of modern instruments was increased and new methods of investigation were invented, new conquests were made in the sidereal domain! Galileo's telescope had immense treasures to look for in the sky. In this age the improvements in the telescope have made known Uranus and Neptune and more than three hundred minor planets, with, a few years ago, the two satellites of Mars. Numerous comets and hundreds of smaller nebulae discovered every year give additional proof that a harvest is always awaiting reapers in the sky. When we consider the immensity of the universe, how could it be otherwise?
Analogy teaches us that the sun is one of the innumerable stars that spangle the firmament with their lights, and that each star is the center of a system like that to which we belong, and of which the sun is the center. Of all these suns, centers of planetary systems, only a few thousand are visible to the naked eye, while telescopes reveal millions of them. Then, if we consider the nebulæ—those little milky spots scattered in all the zones of the sky—if we remark that nearly all of them can, by the aid of strong optical powers, be resolved into thousands of luminous points, and that consequently they are presented to our eyes as immense milky ways investing distant universes, we arrive at the astounding conclusion that little vaporous nothings, which we can hardly distinguish with our strongest instruments, form, not a universe like our solar system, but that each of them is an agglomeration of myriads of universes, the extent and number of which can not be imagined.—Translated for The Popular Science Monthly from Ciel et Terre.