Conversations on the Plurality of Worlds

by M. de Fontenelle

[22] We have a convincing proof of the light reflected from the earth at this time, in the dusky light perceived on a part of the moon that is not enlightened by the sun. Astron. Art. 1412.

Enough—said the Marchioness, in her lively manner; I shall easily learn the rest when I like: let me stop a moment, and trace the moon through her monthly circle. I see that in general that planet and the earth have very different degrees of light, and I imagine that when we have the full-moon all the luminous side of the moon is turned toward all the part of our globe which is obscure; and that, at that time, the inhabitants cannot discern us at all, but say they have new-earth. I should not chuse to be obnoxious to reproach for obliging you to enter into a long explanation of any thing so easily understood, but the eclipses—how are they effected? You could guess it without difficulty, I replied. When we have a new moon, and she, being between us and the sun, presents her dark side to our luminous half, the shadow of this obscure part falls on the earth; so that wherever the moon is in a direct line under the sun, she hides that luminary from our sight, and darkens a part of the enlightened side of our globe; this, then, forms an eclipse of the sun to us during the day-time, and an eclipse of the earth to the moon during her night. When the moon is at the full, the earth is between her and the sun, the shaded side of the earth towards the light side of the moon. If the earth's shadow fall directly on the moon, it darkens the luminous half that we see; 'tis then we have an eclipse of the moon in our night, and the moon, an eclipse of the sun in her day. What prevents an eclipse every time the moon is between the sun and us, or the earth between the sun and moon, is this; it often happens that these three bodies are not placed exactly in a line, in which case the one that would occasion the eclipse throws its shadow on one side of the other and consequently does not obstruct its light.

I am very much astonished, said the Marchioness, that there is so little mystery in eclipses, and that being produced by such simple means, every body does not discover the cause of them. In truth, answered I, there are many people, who from the emotions they feel at one of these phenomena, appear to have little chance of finding out the occasion of them at present. Throughout the East-Indies, when the sun and moon are eclipsed, the inhabitants believe that a great dragon with his black claws is going to seize these luminaries; and all the time the eclipse lasts, you may see whole rivers covered with the heads of these Indians, who have put themselves up to the throat in water, because, according to their notions, this is a very religious act, and will induce the sun or moon to defend itself bravely against the dragon. In America, it was thought that the sun and moon were angry when they were eclipsed, and every kind of absurdity was practised to regain their favour. The Grecians too, who had arrived at such a height of refinement—did they not, for a long time, believe that the moon was eclipsed by the power of sorcery, and that the magicians caused her to descend from the skies and cast a baneful influence on the herbs? And were not we likewise in great alarm, but two-and-thirty years ago,[23] at a total eclipse of the sun? Did not an immense number of people shut themselves up in caves and cellars; and were they easily persuaded to leave them by the philosophers who wrote so much to re-assure them?

[23] 1654. There have been others in Europe in 1724, 1715, and 1716.

Really, replied she, all that is too ridiculous. There ought to be a decree passed to prevent any body from ever talking of eclipses, lest the memory of these follies should be perpetuated. The decree, said I, should extend so far as to obliterate the memory of every subject, for I can think of nothing in the world which is not the monument of some human folly.

Answer me this question, said the Marchioness:—Are the inhabitants of the moon as much afraid of eclipses as those of the earth? How ridiculous it is if the Indians of that world put themselves up to the chin in water; if the Americans believe the earth is angry with them; if the Greeks imagine we are enchanted, and suppose we shall injure their herbs; and in short, if we are inflicting on them all the terror they have caused us? I have no doubt but that is the case, answered I; for why should the good folks in the moon have more sense than we? What right have they to frighten us, unless we can frighten them? I dare say, added I, laughing; that, as a prodigious number of men have been, and still are, silly enough to worship the moon; so there are some in the moon that pay their adorations to the earth, and that they are kneeling to one another. If it be so, she replied, we may pretend to have an influence on the moon, and to produce the crisis in the diseases of her sick people, but as a little common sense in the dwellers on that globe would be sufficient to destroy all these honours, I must confess I am afraid they will have the advantage over us.

Don't alarm yourself, said I; 'tis not probable that we are the only fools in the universe. There is something in ignorance that is calculated for general reception, and though I can only guess the character of the people in question, yet I have no more doubt, that could we form the comparison, we should find ourselves equal to them, than I have that the accounts are true that we receive of their globe.

What accounts do you receive enquired she. Those, I replied, that are given us by the learned who travel there every day by the assistance of telescopes. They tell us that they have discovered in the moon earth, seas, lakes, elevated mountains, and profound abysses.

You astonish me, cried the Marchioness: I cannot imagine the possibility of discovering mountains and abysses, from the great irregularity they cause on the surface of the globe; but how do they distinguish earth from sea? Because, answered I, the water,[24] by suffering part of the light to pass through it, and consequently reflecting less than the earth, has, at a distance, the appearance of dark spots; whilst the solid parts, by reflecting all the light, look much more brilliant. The illustrious M. Cassini, who has acquired a greater knowledge of the celestial bodies than any man in the world, discovered in the moon something which separates, then re-unites, and afterwards loses itself in a cavity. We have reason to believe, from its appearance that this is a river. In short all these different parts are now so well known to us, that they have been named after our great men. One place is called Copernicus, another Archimedes, another Gabileus. Other parts have fancy names; there is a promontory of decams, a sea of nectar, and so on; in fact our description of the moon is so particular, that if a learned man was to take a journey there, he would be in no more danger of losing himself than I should in Paris.

[24] It is proved that there is no water in the moon, but there are volcanoes; they may even be seen without a telescope, which was the case on the 7th of March, 1794. Philos. Trans.