Dreams of an astronomer

by Camille Flammarion

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Let us summarise in a few words the results of this chapter.

On the Moon no organic matter can exist; we may suppose living beings to exist in a small zone of Mercury; the surface of Venus is very probably habitable in most of its regions; Mars is certainly habitable and probably under such conditions that certain species of our plants and animals could, if transported to that planet, continue to live there.

For the other planets the possibility of habitation cannot be entirely denied, but the existence of living beings on their soil is not probable. Let us add, for the sake of completeness, that on the Sun, which radiates the most intense heat, and on those innumerable other suns which we call stars and which the telescope reveals to us, living matter certainly does not exist.

It follows that of the millions of stars visible to us in the universe there are only two or three which we could consider with any certainty capable of being inhabited as we conceive it. That seems a rather unsatisfying result, which allows an icy sentiment of loneliness in infinite space to take possession of our souls.

We have seen in the first part of our work how the speculations of those who formerly discussed the habitability of the planets not only raised the question whether such and such a planet was inhabited, but also tackled the much vaster problem of the particular characters of the beings which lived there. After attentively following the discussion, nobody should ask to penetrate further into this question. It has indeed been a great effort to obtain a positive result at all, even while restricting the population of the planets to the simplest forms of organised matter. The number of forms under which it shows itself on the Earth is so considerable that we can only be dazed by its abundance, and this impression must be even increased if we remember that the possible forms are far from being exhausted and that we only know those which, satisfying terrestrial conditions, have been able to survive by adapting themselves to their surroundings. We do not exaggerate in declaring that Nature recognises no limit to the number of forms which can harbour life, and this observation is an argument in favour of those who desire to find reasonable or superior beings in distant worlds. It indicates that as soon as the first germs of life exist, the possibility of a complete development is there, and that however different the external conditions may be, Nature is not at a loss for varieties of forms of life. That is why we have the right to hope that on Mars, for instance, there are beings who not only show manifestations of animal life, but who are endowed with intellectual faculties. That, however, is all we can acknowledge: the right to hope and not to a certainty.

Yet at the risk of exposing ourselves to a criticism similar to that which we have in the first part directed against other authors, we would now invite the reader to follow us for a moment into the domain of speculation and hypothesis.

THE POSSIBILITY OF BEINGS OF DIFFERENT CHEMICAL CONSTITUTION

In this chapter Scheiner develops the idea indicated above (page 127) on the possibility of the existence in other worlds of living beings entirely different from ourselves.

We have up to now (he writes) understood by organised matter something of which carbon, combined with hydrogen, nitrogen, and other elements, is the principal chemical component. Carbon is the essential constituent; organic chemistry is the chemistry of carbon. We do not know any other substance which would allow of such an array of combinations, but the possibility of such a body cannot be denied. While on Earth all life is bound up with carbon compounds, one may suppose that in entirely different circumstances another element might show itself capable of supporting the conditions of life in combinations which might resist greater heat without decomposition or greater cold without becoming torpid. A few years ago we seemed to be on the track of something like that. Silicon is the element which has the greatest chemical analogy to carbon, and in combination with oxygen it is found in enormous quantities in the form of silica, and all its combinations have very characteristic properties. Just as in organic matter every being forms itself into cells by fission or conjugation, so also can we produce from combinations of silicic acid a cell from which under our eyes an object develops which has a vegetable appearance. This experiment, easy to make, is perhaps unknown to many of our readers, and therefore we must say a little more about it.