Curiosities of the Sky - Garrett P. Serviss (best book clubs txt) 📗

days. Its mean density is 71 per cent of the earth’s, and the force of gravity on its surface is 38 per cent of that on the surface of the earth; i.e., a body weighing one hundred pounds on the earth would, if transported to Mars, weigh but thirty-eight pounds. The inclination of its equator to the plane of its orbit differs very little from that of the earth’s equator, and its axial rotation occupies 24 hours 37

minutes. so that the length of day and night, and the extent of the seasonal changes on Mars, are almost precisely the same as on the earth. But owing to the greater length of its year, the seasons of Mars, while occurring in the same order, are almost twice as long as ours. The surface of the planet is manifestly solid, like that of our globe, and the telescope reveals many permanent markings on it, recalling the appearance of a globe on which geographical features have been represented in reddish and dusky tints. Around the poles are plainly to be seen rounded white areas, which vary in extent with the Martian seasons, nearly vanishing in summer and extending widely in winter. The most recent spectroscopic determinations indicate that Mars has an atmosphere perhaps as dense as that to be found on our loftiest mountain peaks, and there is a perceptible amount of watery vapor in this atmosphere. The surface of the planet appears to be remarkably level, and it has no mountain ranges. No evidences of volcanic action have been discovered on Mars. The dusky and reddish areas were regarded by the early observers as respectively seas and lands, but at present it is not believed that there are any bodies of water on the planet. There has never been much doubt expressed that the white areas about the poles represent snow.

It will be seen from this brief description that many remarkable resemblances exist between Mars and the earth, and there is nothing wonderful in the fact that the question of the habitability of the former has become one of extreme and widespread interest, giving rise to the most diverse views, to many extraordinary speculations, and sometimes to regrettably heated controversy. The first champion of the habitability of Mars was Sir William Herschel, although even before his time the idea had been suggested. He was convinced by the revelations of his telescopes, continually increasing in power, that Mars was more like the earth than any other planet. He could not resist the testimony of the polar snows, whose suggestive conduct was in such striking accord with what occurs upon the earth. Gradually, as telescopes improved and observers increased in number, the principal features of the planet were disclosed and charted, and “areography,”

as the geography of Mars was called, took its place among the recognized branches of astronomical study. But it was not before 1877

that a fundamentally new discovery in areography gave a truly sensational turn to speculation about life on “the red planet.” In that year Mars made one of its nearest approaches to the earth, and was so situated in its orbit that it could be observed to great advantage from the northern hemisphere of the earth. The celebrated Italian astronomer, Schiaparelli, took advantage of this opportunity to make a trigonometrical survey of the surface of Mars — as coolly and confidently as if he were not taking his sights across a thirty-five-million-mile gulf of empty space — and in the course of this survey he was astonished to perceive that the reddish areas, then called continents, were crossed in many directions by narrow, dusky lines, to which he gave the suggestive name of “canals.” Thus a kind of firebrand was cast into the field of astronomical speculation, which has ever since produced disputes that have sometimes approached the violence of political faction. At first the accuracy of Schiaparelli’s observations was contested; it required a powerful telescope, and the most excellent “seeing,” to render the enigmatical lines visible at all, and many searchers were unable to detect them. But Schiaparelli continued his studies in the serene sky of Italy, and produced charts of the gridironed face of Mars containing so much astonishing detail that one had either to reject them in toto or to confess that Schiaparelli was right. As subsequent favorable oppositions of Mars occurred, other observers began to see the “canals” and to confirm the substantial accuracy of the Italian astronomer’s work, and finally few were found who would venture to affirm that the “canals” did not exist, whatever their meaning might be.

When Schiaparelli began his observations it was generally believed, as we have said, that the dusky areas on Mars were seas, and since Schiaparelli thought that the “canals” invariably began and ended at the shores of the “seas,” the appropriateness of the title given to the lines seemed apparent. Their artificial character was immediately assumed by many, because they were too straight and too suggestively geometrical in their arrangement to permit the conclusion that they were natural watercourses. A most surprising circumstance noted by Schiaparelli was that the “canals” made their appearance after the melting of the polar snow in the corresponding hemisphere had begun, and that they grew darker, longer, and more numerous in proportion as the polar liquidation proceeded; another very puzzling observation was that many of them became double as the season advanced; close beside an already existing “canal,” and in perfect parallelism with it, another would gradually make its appearance. That these phenomena actually existed and were not illusions was proved by later observations, and today they are seen whenever Mars is favorably situated for observation.

In the closing decade of the nineteenth century, Mr Percival Lowell took up the work where Schiaparelli had virtually dropped it, and soon added a great number of “canals” to those previously known, so that in his charts the surface of the wonderful little planet appears covered as with a spider’s web, the dusky lines criss-crossing in every direction, with conspicuous knots wherever a number of them come together. Mr Lowell has demonstrated that the areas originally called seas, and thus named on the earlier charts, are not bodies of water, whatever else they may be. He has also found that the mysterious lines do not, as Schiaparelli supposed, begin and end at the edges of the dusky regions, but often continue on across them, reaching in some cases far up into the polar regions. But Schiaparelli was right in his observation that the appearance of the “canals” is synchronous with the gradual disappearance of the polar snows, and this fact has become the basis of the most extraordinary theory that the subject of life in other worlds has ever given birth to.

Now, the effect of such discoveries, as we have related, depends upon the type of mind to whose attention they are called. Many are content to accept them as strange and inexplicable at present, and to wait for further light upon them; others insist upon an immediate inquiry concerning their probable nature and meaning. Such an inquiry can only be based upon inference proceeding from analogy. Mars, say Mr Lowell and those who are of his opinion, is manifestly a solidly incrusted planet like the earth; it has an atmosphere, though one of great rarity; it has water vapor, as the snows in themselves prove; it has the alternation of day and night, and a succession of seasons closely resembling those of the earth; its surface is suggestively divided into regions of contrasting colors and appearance, and upon that surface we see an immense number of lines geometrically arranged, with a system of symmetrical intersections where the lines expand into circular and oval areas — and all connected with the annual melting of the polar snows in a way which irresistibly suggests the interference of intelligence directed to a definite end. Why, with so many concurrent circumstances to support the hypothesis, should we not regard Mars as an inhabited globe?

But the differences between Mars and the earth are in many ways as striking as their resemblances. Mars is relatively small; it gets less than half as much light and heat as we receive; its atmosphere is so rare that it would be distressing to us, even if we could survive in it at all; it has no lakes, rivers, or seas; its surface is an endless prairie. and its “canals” are phenomena utterly unlike anything on the earth. Yet it is precisely upon these divergences between the earth and Mars, this repudiation of terrestrial standards, that the theory of “life on Mars,” for which Mr Lowell is mainly responsible, is based. Because Mars is smaller than the earth, we are told it must necessarily be more advanced in planetary evolution, the underlying cause of which is the gradual cooling and contraction of the planet’s mass. Mars has parted with its internal heat more rapidly than the earth; consequently its waters and its atmosphere have been mostly withdrawn by chemical combinations, but enough of both yet remain to render life still possible on its surface. As the globe of Mars is evolutionally older than that of the earth, so its forms of organic life may be proportionally further advanced, and its inhabitants may have attained a degree of cultivated intelligence much superior to what at present exists upon the earth. Understanding the nature and the causes of the desiccation of their planet, and possessing engineering science and capabilities far in advance of ours, they may be conceived to have grappled with the stupendous problem of keeping their world in a habitable condition as long as possible. Supposing them to have become accustomed to live in their rarefied atmosphere (a thing not inconceivable, since men can live for a time at least in air hardly less rare), the most pressing problem for them is that of a water-supply, without which plant life cannot exist, while animal life in turn depends for its existence upon vegetation. The only direction in which they can seek water is that of the polar regions, where it is alternately condensed into snow and released in the liquid form by the effect of the seasonal changes. It is, then, to the annual melting of the polar snow-fields that the Martian engineers are supposed to have recourse in supplying the needs of their planet, and thus providing the means of prolonging their own existence. It is imagined that they have for this purpose constructed a stupendous system of irrigation extending over the temperate and equatorial regions of the planet. The “canals” represent the lines of irrigation, but the narrow streaks that we see are not the canals themselves, but the irrigated bands covered by them. Their dark hue, and their gradual appearance after the polar melting has begun, are due to the growth of vegetation stimulated by the water. The rounded areas visible where several “canals” meet and cross are called by Mr Lowell “oases.” These are supposed to be the principal centers of population and industry. It must be confessed that some of them, with their complicated systems of radiating lines, appear to answer very well to such a theory. No attempt to explain them by analogy with natural phenomena on the earth has proved successful.

But a great difficulty yet remains: How to explain the seemingly miraculous powers of the supposed engineers? Here recourse is had once more to the relative smallness of the planet. We have remarked that the force of gravity on Mars is only thirty-eight per cent of that on the earth. A steam-shovel driven by a certain horse-power would be nearly three times as effective there as here. A man of our stature on Mars would find his effective strength increased in the same proportion. But just because of the slight force of gravity there, a Martian might attain to the traditional stature of Goliath