Astronomy for Amateurs

by Camille Flammarion

The humble little planet that we inhabit presents itself to us as a brimming cup, overflowing at every outlet. Life is everywhere. From the bottom of the seas, from the valleys to the mountains, from the vegetation that carpets the soil, from the mold in the fields and woods, from the air we breathe, arises an immense, prodigious, and perpetual murmur. Listen! it is the great voice of Nature, the sum of all the unknown and mysterious voices that are forever calling to us, from the ocean waves, from the forest winds, from the 300,000 kinds of insects that are redundant everywhere, and make a lively community on the surface of our globe. A drop of water contains thousands of curious and agile creatures. A grain of dust from the streets of Paris is the home of 130,000 bacteria. If we turn over the soil of a garden, field, or meadow, we find the earthworms working to produce assimilable slime. If we lift a stone in the path, we discover a crawling population. If we gather a flower, detach a leaf, we everywhere find little insects living a parasitic existence. Swarms of midges fly in the sun, the trees of the wood are peopled with nests, the birds sing, and chase each other at play, the lizards dart away at our approach, we trample down the antheaps and the molehills. Life enwraps us in an inexorable encroachment of which we are at once the heroes and the victims, perpetuating itself to its own detriment, as imposed upon it by an eternal reproduction. And this from all time, for the very stones of which we build our houses are full of fossils so prodigiously multiplied that one gram of such stone will often contain millions of shells, marvels of geometrical perfection. The infinitely little is equal to the infinitely great.

Life appears to us as a fatal law, an imperious force which all obey, as the result and the aim of the association of atoms. This is illustrated for us upon the Earth, our only field of direct observation. We must be blind not to see this spectacle, deaf not to hear its reaching. On what pretext could one suppose that our little globe which, as we have seen, has received no privileges from Nature, is the exception; and that the entire Universe, save for one insignificant isle, is devoted to vacancy, solitude, and death?

We have a tendency to imagine that Life can not exist under conditions other than terrestrial, and that the other worlds can only be inhabited on the condition of being similar to our own. But terrestrial nature itself demonstrates to us the error of this way of thinking. We die in the water: fishes die out of the water. Again, short-sighted naturalists affirm categorically that Life is impossible at the bottom of the sea: 1, because it is in complete darkness; 2, because the terrible pressure would burst any organism; 3, because all motion would be impossible there, and so on. Some inquisitive person sends down a dredge, and brings up lovely creatures, so delicate in structure that the daintiest touch must proceed with circumspection. There is no light in these depths: they make it with their own phosphorescence. Other inquirers visit subterranean caverns, and discover animals and plants whose organs have been transformed by adaptation to their gloomy environment.

What right have we to say to the vital energy that radiates round every Sun of the Universe: "Thus far shalt thou come, and no further"? In the name of Science? An absolute mistake. The Known is an infinitesimal island in the midst of the vast ocean of the Unknown. The deep seas which seemed to be a barrier are, as we have seen, peopled with special life. Some one objects: But after all, there is air there, there is oxygen: oxygen is indispensable: a world without oxygen would be a world of death, an eternally sterile desert. Why? Because we have not yet come across beings that can breathe without air, and live without oxygen? Another mistake. Even if we did not know of any, it would not prove that they do not exist. But as it happens, we do know of such: the anærobia. These beings live without air, without oxygen. Better still: oxygen kills them!

All the evidence goes to show that in interpreting as we ought the spectacle of terrestrial life, and the positive facts acquired by Science, we should enlarge the circle of our conceptions and our judgments, and not limit extra-terrestrial existence to the servile image of what is in existence here below. Terrestrial organic forms are due to local causes upon our planet. The chemical constitution of water and of the atmosphere, temperature, light, density, weight, are so many elements that have gone to form our bodies. Our flesh is composed of carbon, nitrogen, hydrogen, and oxygen combined in the state of water, and of some other elements, among which we may instance sodium chloride (salt). The flesh of animals is not chemically different from our own. All this comes from the water and the air, and returns to them again. The same elements, in very minute quantities, make up all living bodies. The ox that browses on the grass is formed of the same flesh as the man who eats the beef. All organized terrestrial matter is only carbon combined in variable proportions with hydrogen, nitrogen, oxygen, etc.

But we have no right to forbid Nature to act differently in worlds from which carbon is absent. A world, for example, in which silica replaces carbon, silicic acid carbonic acid, might be inhabited by organisms absolutely different from those which exist on the Earth, different not only in form, but also in substance. We already know stars and suns for which spectral analysis reveals a predominance of silica, e.g., Rigel and Deneb. In a world where chlorine predominated, we might expect to find hydrochloric acid, and all the fecund family of chlorides, playing an important part in the phenomena of life. Might not bromine be associated in other formations? Why, indeed, should we draw the line at terrestrial chemistry? What is to prove that these elements are really simple? May not hydrogen, carbon, oxygen, nitrogen, and sulphur all be compounds? Their equivalents are multiples of the first: 1, 6, 8, 14, 16. And is even hydrogen the most simple of the elements? Is not its molecule composed of atoms, and may there not exist a single species of primitive atom, whose geometric arrangement and various associations might constitute the molecules of the so-called simple elements?

In our own solar system we discover the essential differences between certain planets. In the spectrum of Jupiter, for instance, we are aware of the action of an unknown substance that manifests itself by a marked absorption of certain red rays. This gas, which does not exist upon the Earth, is seen still more obviously in the atmospheres of Saturn and Uranus. Indeed, upon this last planet the atmosphere appears, apart from its water vapor, to have no sort of analogy with our own. And in the solar spectrum itself, many of the lines have not yet been identified with terrestrial substances.

The interrelation of the planets is of course incontrovertible, since they are all children of the same parent. But they differ among themselves, not merely in respect of situation, position, volume, mass, density, temperature, atmosphere, but again in physical and chemical constitution. And the point we would now accent is that this diversity should not be regarded as an obstacle to the manifestations of life, but, on the contrary, as a new field open to the infinite fecundity of the universal mother.

When our thoughts take wing, not only to our neighbors, Moon, Venus, Mars, Jupiter, or Saturn, but still more toward the myriads of unknown worlds that gravitate round the suns disseminated in space, we have no plausible reason for imagining that the inhabitants of these other worlds of Heaven resemble us in any way, whether in form, or even in organic substance.