Examination of these star motions reveals the fact that our Sun is plunging with all his system (the Earth included) toward the Constellation of Hercules. We are changing our position every moment: in an hour we shall be 70,000 kilometers (43,500 miles) farther than we are at present. The Sun and the Earth will never again traverse the space they have just left, and which they have deserted forever. And here let us pause for an instant to consider the _variable stars_. Our Sun, which is constant and uniform in its light, does not set the type of all the stars. A great number of them are variable--either periodically, in regular cycles--or irregularly. We are already acquainted with the variations of Algol, in Perseus, due to its partial eclipse by a dark globe gravitating in the line of our vision. There are several others of the same type: these are not, properly speaking, variable stars. But there are many others the intrinsic light of which undergoes actual variations. In order to realize this, let us imagine that our Earth belongs to such a sun, for example, to a star in the southern constellation of the Whale, indicated by the letter [omicron], which has been named the "wonderful" (Mira Ceti). Our new sun is shining to-day with a dazzling light, shedding the gladness of his joyous beams upon nature and in our hearts. For two months we admire the superb orb, sparkling in the azure illuminated with its radiance. Then of a sudden, its light fades, and diminishes in intensity, though the sky remains clear. Imperceptibly, our fine sun darkens; the atmosphere becomes sad and dull, there is an anticipation of universal death. For five long months our world is plunged in a kind of penumbra; all nature is saddened in the general woe. But while we are bewailing the cruelty of our lot, our cherished luminary revives. The intensity of its light increases slowly. Its brilliancy augments, and finally, at the end of three months, it has recovered its former splendors, and showers its bright beams upon our world, flooding it with joy. But--we must not rejoice too quickly! This splendid blaze will not endure. The flaming star will pale once more; fade back to its minimum; and then again revive. Such is the nature of this capricious sun. It varies in three hundred and thirty-one days, and from yellow at the maximum, turns red at the minimum. This star, Mira Ceti, which is one of the most curious of its type, varies from the second to the ninth magnitudes: we cite it as one example; hundreds of others might be instanced. Thus the sky is no black curtain dotted with brilliant points, no empty desert, silent and monotonous. It is a prodigious theater on which the most fantastic plays are continually being acted. Only--there are no spectators.