  I am going to say a few words about the moon; but there are many matters relating to her of great interest which I must leave untouched, for the simple reason that there is not room to speak of them in a single paper. Thus the moon's changes of shape from the horned moon to the half, and thence to the full moon, with the following changes from full to half, and so to the horned form again, are well worth studying; but I should want all the space I am going to occupy, merely to explain properly those changes alone. So a study of the way in which the moon rules the tides would, I am sure, interest every thoughtful reader; but there is not room for it here. Let us now turn to consider the moon; not as the light which makes our nights beautiful, nor as the body which governs the mighty ocean in its tidal sway, but as another world,—the companion planet of the earth. It has always been a matter not only of the deepest curiosity, but of the greatest scientific import, whether other planets, and particularly our own satellite, are inhabited or exhibit any traces whatever of animal or vegetable life. One or two astronomers have claimed the discovery of vegetation on the moon's surface by reason of the periodic appearance of a greenish tint; but as the power of the telescope can bring the moon to within only about a hundred and twenty miles of us, these alleged appearances cannot be satisfactorily verified. The moon is a globe, two thousand one hundred and sixty-five miles in diameter; very much less, therefore, than our earth, which has a diameter of about seven thousand nine hundred and twenty miles. Thus the moon's surface is less than one thirteenth of the earth's. Instead of two hundred millions of square miles as the earth has, the moon has only about fourteen millions of square miles, or about the same surface as North and South America together, without the great American Islands of the Arctic regions. The volume of the earth exceeds that of the moon more than forty-nine times. But the moon's substance is somewhat lighter. Thus the mass, or quantity of matter in the moon, instead of being a forty-ninth part of the earth's, is about an eighty-first part. This small companion world travels like our own earth around the sun, at a distance of ninety-three millions of miles. The path of the moon around the sun is, in fact, so nearly the same as that of the earth that it would be almost impossible to distinguish one from the other, if they were both drawn on a sheet of paper a foot or so in diameter. You may perhaps be surprised to find me thus saying that the moon travels round the sun, when you have been accustomed to hear that the moon travels round the earth. In reality, however, it is round the sun the moon travels, though certainly the moon and the earth circle around each other. The distance of the moon from the earth is not always the same; but the average, or mean distance, amounts to about two hundred and thirty-eight thousand eight hundred and twenty-eight miles. This is the distance between the centers of the two globes. With this distance separating them, the companion worlds—the earth and the moon—circle round each other, as they both travel round the central sun. But now you will be curious to learn whether our companion planet, the moon, really presents the appearance of a world, when studied with a powerful telescope. If we judged the moon in this way, we should say that she is not only not inhabited by living creatures, but that she could not possibly be inhabited. What is it that makes our earth a fit abode for us who live upon it? Her surface is divided into land and water. We live on the land; but without the water we should perish. Were there no water, there would be no clouds, no rain, no snow, no rivers, brooks, or other streams. Without these, there could be no vegetable life; and without vegetable life, there could be no animal life, even if animals themselves could live without water. Yet again, the earth's globe is enwrapped in an atmosphere,—the air we breathe. Without this air, neither animals nor vegetables could live. I might go further and show other features of the earth, which we are at present justified in regarding as essential to the mere existence, and still more to the comfort, of creatures living upon the earth. Now, before the telescope was invented, many astronomers believed that there was water on the moon, and probably air also. But as soon as Galileo examined the moon with his largest telescope (and a very weak telescope it was), he found that whatever the dark parts of the moon may be, they certainly are not seas. More and more powerful telescopes have since been turned on the moon. It has been shown that there are not only no seas, but no rivers, pools, lakes, or other water surfaces. No clouds are ever seen to gather over any part of the moon's surface. In fact, nothing has ever yet been seen on the moon which suggests in the slightest degree the existence of water on her surface, or even that water could at present possibly exist; and, of course, without water it is safe to infer there could be neither vegetable nor animal existence. It would seem, then, that apart from the absence of air on the moon, there is such an entire absence of water that no creatures now living on the earth could possibly exist upon the moon. Certainly man could not exist there, nor could animals belonging to any except the lowest orders of animal life. |
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