Conversations on the Plurality of Worlds

by M. de Fontenelle

What we call a vortex is a quantity of matter, whose detached parts move all in the same direction, but allowed at the same time to have some little movements peculiar to themselves, provided they still pursue the general course. A vortex of wind, for instance, is a vast number of little particles of air, turning all together in a circular direction, and involving whatever comes in their way. The planets you know are borne along by the celestial fluid, which is prodigiously subtle and active. All the celestial matter, from the sun to the fixed stars, constantly turns round, carries the planets along with it, and makes them proceed round the sun in the same direction, but in longer or shorter periods, according to their distance from the centre. Even the sun is made to turn on his axis by being exactly in the midst of this moving matter; you will therefore observe, that if the earth were in the central situation she could not be exempted from this rotation.

Such is the great vortex of which the sun is master; but the planets, at the same time, form little vortices in imitation of the sun. Each of them whilst turning round the sun, turns likewise on itself, and carries in its motion a certain portion of the celestial matter, which is ready to receive any impulse that would not prevent it from following the general course: this is a vortex of any particular planet, and it extends as far as the motion of this planet has any influence. If a smaller planet comes within the vortex of a larger one, it is irresistibly carried round that larger one, and altogether, the large, and the small planet, and the vortex that encloses them, perform their revolution round the sun. Thus at the commencement of creation we obliged the moon to follow us because she came within the influence of our vortex, and was by that mean subjugated to our will. Jupiter, the planet we were speaking of, was more fortunate, or more powerful than the earth. Four little planets were in his neighbourhood, and he became master of them all; and we, who are a planet of some importance, would probably have felt his power if we had been near him. He is a thousand times larger than the earth;[38] and would easily have drawn us into his vortex, and made us one of his moons; instead of this we have a planet to attend on us: so true is it that the situation into which we are thrown decides the fate of our lives.

[38] We may even say thirteen hundred times.

And how do we know, answered the Marchioness, that we shall always remain where we are? I begin to tremble lest we should be foolish enough to approach such an enterprizing planet as Jupiter, or that he should come to us, for the sake of drawing us into his vortex; for I can't help thinking, from your description of the agitated state of this celestial fluid, that it must move the planets irregularly, sometimes urging them nearer together, sometimes sending them to a greater distance. We may as well expect to gain as to lose by such an eccentric motion, said I; perhaps we may make a conquest of Mercury or Mars, which are smaller planets, and incapable of resisting us. However we have no occasion for either hope or fear; the planets will remain in their places; and, like the former kings of China, they are forbidden to aim at conquest. You have observed that when oil is mixed with water, the oil swims at the top. Put any substance that is extremely light on both these, and the oil will support it, so that it shall not touch the water: but put a heavier body, of a certain weight, it will pass through the oil, which is too weak to stop it, and keep falling till it meets the water, which has sufficient force to bear it up. Thus two liquors put together, being of unequal weight, will not mix, but place themselves in different situations; and neither will one rise, nor the other descend: pour on these other liquors which are of a nature to remain separate, and the same effect is still produced. In like manner the celestial matter which fills this grand vortex, is in separate strata, encircling each other, and of unequal weight, like oil and water, and some other liquors. Some planets likewise are heavier than others,[39] each therefore stops in the layer which has the degree of force necessary for supporting it, and keeping it in a state of equilibrium; and you must be convinced that it can never go beyond this stratum.

[39] The Cartesians carried their illusion so far as to believe that so solid a mass as a planet could be steadily supported by the ætherial fluid, the most subtle of all fluids.

I understand, replied the Marchioness, that the different degrees of weight are sufficient to keep them in their proper ranks. I wish with all my heart there was some such regulating power among us, that would serve to fix people in the situation most suitable to them! You have quite removed my uneasiness with regard to Jupiter. I am very glad he will let us remain quietly with our little vortex, and single moon. I feel very well contented with one attendant, and do not envy him his four.

You would do wrong if you did, said I; he has no more than are necessary. He is five times farther from the sun than we, that is, a hundred and sixty-five[40] millions of leagues distant from it, consequently his moons receive, and reflect, but a feeble light: the number therefore compensates for the little effect produced by each: were they not separately so inefficient, four moons would appear unnecessary, as Jupiter turns on his axis in ten hours, and of course the nights are very short. The satellite which is the nearest to Jupiter, performs its circle round him in two-and-forty hours; the next in three days and a half; the third, in seven; the fourth, in seventeen; and by the inequality of their progress, they form a most pleasing spectacle for this planet. At one time they rise all four together; then, almost immediately separate; sometimes they are all at the full, placed in a line, one above another; afterwards they are seen at equal distances in the sky; then when two are rising the other two will set. Above all I should like to see the perpetual variety of eclipses among them, for there is not a day passes in which they do not eclipse each other, or the sun.[41] Surely as eclipses are so familiar to the inhabitants of that world, they must be considered a subject of amusement, rather than terror, as they are here.

[40] Calculating with more exactness, 179.

[41] Or; we may add, in which they are not eclipsed by the shadow of Jupiter, which happens the most frequently.

You will not fail, I suppose, said the Marchioness, to people these four moons, though they are only little subaltern planets, intended merely to give light to another during the night. Undoubtedly not, I replied. These little planets are not unworthy of inhabitants because they are unfortunate enough to be subjected to a larger planet.