Conversations on the Plurality of Worlds

by M. de Fontenelle

I think, then, answered she, these satellites ought to be like colonies to Jupiter; that their inhabitants should, if possible, receive from him their laws and customs, and in return, render him some degree of homage, and always consider the great planet with respect. Would it not be needful, said I, for the moons occasionally to send deputies to Jupiter, who should take an oath of fidelity to him? I must own the little superiority we possess over the people in our moon makes me doubt whether Jupiter has much influence over the inhabitants of his satellites, and I think the only superiority he can aspire to is that of impressing them with awe. For of what a terrific size he must appear! To the planets nearest to him he looks sixteen hundred times larger than our moon appears to us.[42] Truly if the Gauls in ancient times were afraid the heavens would fall and crush them to death, the inhabitants of this moon may with greater propriety apprehend the fall of Jupiter. Perhaps, she replied, that is the subject of alarm to them instead of the eclipses, which you assure me they see without fear;[43] for as they are exempt from one folly, they must be subject to some other. Undoubtedly, answered I. The inventor of a third system, which I mentioned the other day, the celebrated Tycho Brahe, one of the greatest astronomers that ever lived, felt none of the vulgar terror at an eclipse; he was too much accustomed to study the nature of such a phenomenon; but what do you think he was afraid of instead?—If when he first went out of doors the first person he saw was an old woman; or if a hare crossed the path he had taken, Tycho Brahe thought the day would be unfortunate, and returning in haste to his apartment, he shut himself up without venturing to engage in any occupation whatever.

[42] Thirty-six times larger than we see the moon: and they receive from him one thousand two hundred and ninety times more light.

[43] Their solar eclipses are of much longer duration than ours.

It would be unjust, said she, if such a man as he could not with impunity overcome the fear of an eclipse, for the inhabitants of the satellite we were speaking of, to be exempted from it on easier terms. We will not spare them: they shall submit to the general doom; and if they escape one error they shall be liable to another.

A difficulty has just occurred to me, continued she, you must remove it if you can: if the earth is so small in comparison of Jupiter, are we visible to the inhabitants of that planet? I am afraid we are unknown to them.

Really I think so, answered I; the earth is certainly too small to be distinguished by them.[44]

[44] The earth at that distance must appear only three seconds and a half in diameter, as the planet Herschel does to us; but our nearness to the sun necessarily prevents them from seeing us at all.

We can only hope that in Jupiter there may be some astronomers who, after taking great pains to compose very excellent telescopes, and availing themselves of the finest nights for making their observations, may at length discover a very little planet which they had never seen before. At first the learned give an account of it in their journal; the rest of the people either hear nothing about it, or laugh at it when they do; the philosophers are discouraged and resolve not to mention it again, and but a few of the inhabitants who are more reasonable than the others will admit the idea. By and by they examine again; they see the little planet a second time; they are then assured of its reality, and even begin to think it has a motion round the sun. After observing it a thousand times, they find out that this revolution is performed in a year: and at last, when the learned have been at great pains to investigate the subject, the inhabitants of Jupiter know that our world is in the universe. The curious eagerly look through their telescopes, and with all their looking, can scarcely discern it.

Were it not disagreeable, said she, to know that from Jupiter we can only be seen through telescopes, I should amuse myself with the idea of all the glasses being pointed towards the earth as ours are towards him, and the mutual curiosity with which the two planets examine each other, and enquire, What world is that? What sort of people inhabit it?

Your imagination is too rapid, I replied; when the astronomers of Jupiter become acquainted with our earth, they do not become acquainted with us: they will not suspect the possibility of its being inhabited; if any one should venture to express such an idea, how they would laugh at him! Perhaps they would even persecute any philosopher who should maintain the opinion. After all I think the inhabitants of Jupiter are too much occupied in making discoveries on their own globe, to concern themselves about us. Jupiter is of such extent, that if they are adepts in navigation their Christopher Columbus must be fully employed. The inhabitants cannot know, even by reputation, a hundredth part of the other inhabitants. In Mercury, on the contrary, they are all neighbours, living familiarly together, and hardly considering the tour of their world more than a pleasant walk. If we are not visible to Jupiter, much less can Venus be so, who is at a still greater distance;[45] and Mercury must be most out of its reach of all, being the smallest, and the most distant. However, the inhabitants can see Mars, their own four satellites, and Saturn with all his moons. Surely then they have planets enough to perplex their astronomers; nature, in kindness, has hid from them the rest.