Part 3

Professor O. M. Mitchell, the first director of the Cincinnati Observatory, in his work on "Popular Astronomy," says, in regard to the doctrine of the plurality of worlds: "It would be most incredible to assert, as some have done, that our planet, so small and insignificant in its proportions when compared with other planets with which it is allied, is the only world in the whole universe filled with sentient, rational and intelligent beings capable of comprehending the grand mysteries of the physical universe."

The eminent French astronomer, M. Flammarion, has, in an eloquent passage in his "Plurality of Worlds," portrayed the vastness of the universe and the utter insignificance of our Earth in the immensity of space: "If advancing with the velocity of light we could traverse from century to century this unlimited number of suns and spheres without ever meeting any limit to this prodigious immensity where God brings forth worlds and beings; looking behind, but no longer knowing in what part of the infinite to find this grain of dust called the Earth, we should stop fascinated and confounded by such a spectacle, and uniting our voice to the concert of universal nature we should say from the depths of our soul, Almighty God! how senseless we were to believe that there was nothing beyond the Earth, and that our abode alone possessed the privilege of reflecting thy greatness and honor."

Compare these elevating thoughts with the shrunken attitude of one who has the conceit to imagine that he and his kind are not only alone in the universe but superadds to this monstrous conception the idea that the millions of great suns are designedly waltzing around solely for his edification and amusement, unmindful of the heedless way in which the millions of his race regard the overpowering majesty of the heavens. To the thousand millions that live to-day, and the thousand, thousand millions that have perished in the past, the starry heavens have never excited an emotion grateful, reverent, or curious, unless a flaming comet, or an eclipse of the Sun or Moon occurred, and then with superstitious fear have they gone grovelling in the dust.

An astronomer imbued with Hebraic conceptions of the universe is poorly equipped to appreciate the arguments in favor of life in other worlds. He may be keen in perceiving lines in the spectrum, and the significance of their lateral displacement, but possessed with a belief--the result of early training--that a little two-legged human molecule could command the Sun and Moon to stand still, a realization of his own insignificance, or the possibility of intelligence in other worlds, must forever remain beyond his grasp. Emerson said "the dogmas shrivel as dry leaves at the door of the observatory." They never shrivel for such minds, but grow and flourish with a density that obscures by, its rankness every rational conception of the heavens above. As an illustration of the attitude of such mentalities we have to go back fifty years, for few survive to-day. Edward Hitchcock, Professor of Geology and Theology at Amherst, wrote a book just fifty years ago entitled "Plurality of Worlds," in which he denounces the idea; but observe the precise way in which he lays down the law: "The planets had no vital tendencies, they could have had such given only by an additional act or series of acts of creative power. As mere inert globes, they had no settled destiny to be the seats of life; they could have had such a destiny only by the appointment of Him who creates living things and puts them in the places which he chooses for them" (page 352).

It may be objected that it is useless to bring up these old theological conceptions, as the world has happily gone beyond them, and only in an atavistic manner do we find a few still holding them; nevertheless it may be safely asserted that fifty years hence we shall look back upon the attitude of certain astronomers to-day with much the same pity and amusement which excites us when we regard the attitude of a similar class in the middle of the last century.

Tyndall expresses the universal belief of thinkers in whatever line of work, that life is by no means confined to this Earth. He says: "Whether the other fixed stars have similar planetary companions or not is to us a matter of pure conjecture, which may or may not enter into our conception of the universe. But probably every thoughtful man believes, with regard to these distant Suns, that there is, in space, something besides our system on which they shine."

One class of objectors to the idea that other worlds are inhabited endeavors to show that our position in the universe is unique, that the solar system itself is quite unlike anything existing elsewhere, and, to cap the climax, that our own little world has just the right amount of water, air, and gravitational force to enable it to be the abode of intelligent life, and nowhere else in the broad expanse of heaven can such physical habitudes be found as will enable life to originate or to exist!

In a memoir on the "Evolution of the Solar System," by Professor T. J. J. See, the author, while not denying the possibility of other systems like our own, still considers our system unique. Here are his words: "Therefore, while observation gives us no grounds for denying the existence of other systems like our own, it does not enable us to affirm, or even to render probable, that such systems do exist." Because a number of binary stars have been discovered in which the two stars are nearly equal in mass, and their orbits highly eccentric, he therefore concludes that the millions of stars that stud the heavens are probably without satellites. The unreasonableness of this attitude is emphasized by realizing that these innumerable suns are similar to our own Sun, as revealed by the spectroscope, and have a similar eruptive energy. Professor Newcomb, however, says: "Evidence is continually increasing that dark and opaque worlds like ours exist and revolve around their primaries." Had Mr. See discovered that every star of the many million was accompanied by another star nearly equal in mass, with its marked eccentric behavior, then only would he be justified in his inference that our solar system was indeed unique. When one realizes that the stars are at such unimaginable distances that the highest powers of the telescope reveal even the nearest of them only as points of light--not as disks--and when one further realizes that the satellites of our Sun, even the largest of them, are diminutive globes compared to the vastness of the Sun, it seems unreasonable if not impossible to entertain the idea that none of these remote stars are accompanied by satellites, and that, therefore, this little Sun of ours stands without parallel in the universe.

Tyndall, in his famous reply to the critics of his Belfast address, in speaking of the origin of life, referred to the Nebular Theory as follows: "According to it our sun and planets were once diffused through space as an impalpable haze out of which by condensation came the solar system. What caused it to condense? Loss of heat. What rounded the sun and planets? That which rounds a tear, molecular force." In these terse and graphic expressions we are made to understand the universality of law. So far as we have sounded the depths of the stellar universe we see the same obedience to gravitational laws, the same flashing lines in the spectrum. We encounter no phenomena that cannot be explained, or at least inferred, by the knowledge we have obtained from our little mote of the Cosmos.

Mr. See thinks it remarkable that "previous investigators have almost invariably approached the problem of cosmogony from the point of view of the planets and satellites, and that no considerable attempt has been made to inquire into the development of the great number of systems observed among the fixed stars." It is true our planetary system has been used as a standard of measurement for the universe, and a very comprehensive standard it has proved to be. The law of universal gravitation was based on terrestrial and lunar observations, spectroscopic analysis was determined in a terrestrial laboratory. As George Iles says, a coal of fire may be raked from a grate and broken up to illustrate the rapid cooling of smaller masses. Even a child's spinning top may be used in an astronomical lecture. The study of our Sun led to the study of the fixed stars, and so our little system has thus far furnished us with examples and illustrations by which we interpret the universe.

In our solar system we have a fair sample of the Cosmos in miniature, though our Sun is so modest in size, compared with the great orbs that appeal to us by their number and brilliancy. So far as our telescopes have sounded the heavens we find nebulous clouds in their structure showing inchoate masses, orbital and spiral arrangements, condensations in their centres. We have the binaries with their extraordinary properties, we have variables with their dark bodies revolving around their primaries. In our little system we also have dark bodies revolving around a luminous primary, from one of which we endeavor to interpret the mysteries of the universe; we have loose masses, as in comets with enormously elongated orbits; we have spheres of insignificant size, with small bodies revolving around them, and these epitomes revolving around a central sun; we have one of these bodies with meteoric rings; and, in the case of our own globe, a satellite of such size that except in the form of its orbit it might well represent a binary in embryo;--and, finally, a host of bodies big enough to reflect the rays of the sun, pursuing their various orbital paths. We are told that the stars are as distant from each other as we are from them. We may regard these systems of nebulæ, variables, doubles, etc., as different kinds or species of heavenly bodies; and to assert that our system is the only individual of the species in the universe seems contrary to all celestial analogy, for do we not have hundreds of binaries, thousands of variables, millions of suns, revealing the same fiery energy and consuming the same elemental fuel?

Professor Newcomb in his "Reminiscences" describes his first sweeping the heavens, at random, with the then new twenty-six inch refractor at the Naval Observatory and discovering a little cluster of stars so small and faint that the individual stars eluded even the great power of this instrument. He says: "I could not help the vain longing which one must sometimes feel under such circumstances, to know what beings might live on planets belonging to what, from an earthly point of view, seemed to be on the border of creation itself." One would suppose that this expression of a longing to ascertain the character of the beings inhabiting planets circling these distant suns would induce one to study a planet analogous to our Earth, and so near in comparison to these unimaginable distances as to be within a hand's grasp, so to speak. The little interest Professor Newcomb has taken in the subject is well expressed in his late book "Astronomy for Everybody." In his chapter on Mars, in which Everybody is certainly interested, he says: "The reader will excuse me for saying anything in this chapter about the possible inhabitants of Mars. He knows just as much of the subject as I do, and that is nothing at all." He might at least have given the various pronouncements of Schiaparelli, Lowell, and others as to the probable character of these remarkable markings on Mars, and their supposed significance.

While Professor Newcomb's attitude on the question of the plurality of worlds has been somewhat conservative in the past he has lately, however, expressed himself on the question in no uncertain terms. In a recent article in "Harper's Magazine," entitled "Probability of Life in Other Worlds," he has lent his sanction to the rational idea that other worlds may be the abode of intelligent creatures. His recognition of the principle will do much to offset the influence if it ever had any, of a recent book published in England by Alfred Russel Wallace, in which the distinguished author attempts to show that this world stands alone as the abode of intelligent life. Despite his epoch-making work with Darwin, nearly fifty years ago, which must forever merit our gratitude, and the charm of his various essays on protective coloring, mimicry, theory of birds' nests, etc., he has since those lucid days expressed convictions of such a nature that if a future DeMorgan should write on human paradoxes he would classify Mr. Wallace as chief among them. A profound believer in evolution, he exempts man from the inexorable logic of the principle with about as much reason as if, confessing his belief in the nebular hypothesis, he should insist that the Earth was an exception.

But to return to Professor Newcomb's recent utterances. In the above-mentioned article he says: "Not only does life, but intelligence, flourish on this globe under great variety of conditions as regards temperature and surroundings, and no sound reason can be shown why, under certain conditions which are frequent in the universe, intelligent beings should not acquire the highest development." Again he says: "Life, not wholly unlike that on the Earth, may therefore exist upon Mars, for anything we know to the contrary. More than this we cannot say." In his final summing up Professor Newcomb says: "It is therefore perfectly reasonable to suppose that beings not only animated but endowed with reason inhabit countless worlds in space."

It would seem as if a mind capable of entertaining an idea of our uniqueness in the universe betrays the survival of a mental condition which, centuries ago, regarded the stars as bits of luminous material expressly designed to illuminate this little earth, around which they all pursued their daily paths.

LOWELL'S BOOK ON MARS

This whole arrangement presents an indescribable simplicity and symmetry which cannot be the work of chance.

SCHIAPARELLI, in writing of the canals.

In a discussion of the surface markings of Mars a broad sketch of what has already been accomplished in the study of that planet should be given for the general reader. I know of no better way of doing this than by giving a brief abstract of Percival Lowell's epoch-making work entitled "Mars." In this book he presents in a clear and striking manner the results of his own work covering continuous observations of the planet for many years. The preface is dated from Flagstaff, Arizona, 1895. Since that time he has issued three volumes of Memoirs, in quarto, of the Lowell Observatory, and a number of Bulletins in which he presents many additional facts confirming previous observations, besides new observations; and finally, in a late Bulletin, he has presented photographs of Mars made by his assistant, Mr. Lampland, in which a number of canals plainly show, thus setting forever at rest the question of the subjective character of the markings. The student must, however, follow the advice of an English reviewer and by all means read the book.

"To determine," says Mr. Lowell, "whether a planet be the abode of life in the least resembling that with which we are acquainted, two questions about it must be answered in turn: first, are its physical conditions such as render it, in our general sense, habitable; and secondly, are there any signs of its actual habitation? These problems must be attacked in their order, for unless we can answer the first satisfactorily, it were largely futile to seek for evidence of the second." The reason why Mars in certain years becomes so conspicuous is that its orbit is highly eccentric. Every two years--the period of its revolution about the Sun--brings it nearest to the Sun, and once in fifteen years we find ourselves between it and the Sun at its nearest approach.

Huyghens, in 1659, made a drawing of the dark region on Mars now known as the Syrtis Major, and, through its disappearance and reappearance, he discovered that the planet rotated on its axis, and roughly determined a daily period of twenty-four hours. For the first time it was known that Mars had a day and a night. As some doubts existed as to the correctness of Huyghens's figures, Cassini in 1666 determined anew the rotation period of Mars and found it to be twenty-four hours and forty minutes. From the white polar caps, the study of which we first owe to Maraldi, it was found that the tilt of its axis to the plane of its orbit was very nearly the same as that of the Earth. As this inclination determines the seasons, it was seen that Mars, like the Earth, had its spring, summer, autumn, and winter. A polar flattening was also observed which was slightly in excess of ours.

"To all forms of life of which we have any conception, two things in Nature are vital, air and water." Has it an atmosphere? Without air no change could take place. The Moon without air remains unchanged, except what gravitation accomplishes in pulling down crater walls. "With Mars it is otherwise. Over the surface of that planet changes do occur, changes upon a scale vast enough to be visible from the Earth." The first sign of change occurs in the polar snow cap. It dwindles in size every two years (the time of a single revolution of Mars around the sun). For nearly two hundred years these white polar caps have been observed to wax and wane. As the Martian winter comes on in the northern hemisphere, for example, the polar cap extends its borders to the temperate zone. As summer comes on the snow cap is seen to dwindle gradually away, till by early autumn it presents but a tiny patch a few hundred miles across. Schiaparelli observed changes in tint which he noticed were correlated with the seasons. In 1894 observations were made continuously from early June till late in November. These dates, in Mars, represent the last of April till the last of August. During this time marked changes took place in the bluish-green areas of the planet. A wave of seasonal change swept down from the pole to the equator. The fact of this occurrence constitutes positive proof of the presence of an atmosphere. In another way the evidence was shown. A series of measurements of the polar and equatorial diameters of Mars were made, and these indicated that a visible layer of twilight atmosphere had been measured. This, Lowell explains by a diagram and other data. It is found, according to Lowell's observations, that the atmosphere is much freer from clouds than had been supposed. He shows conclusively that it is much rarer than that of the Earth. Appearances have been seen, however, which are best explained by assuming them to be clouds.

During the opposition of 1892, Mr. Douglass, at that time an assistant astronomer at the Lowell Observatory, made a special study of the terminator of Mars. A careful study of the terminator for almost every degree of latitude was made, and 733 irregularities were detected. Of this large number, 694 were not only recorded, but measured; and of these, 403 were depressions, and 291 were elevations of the surface. Many of these irregularities were supposed to be clouds, but the arguments to support this attribution are too technical to be presented here. Unmistakable clouds have also been seen moving at a definite rate of speed, as if carried along by the wind.

"To sum up, now, what we know about the atmosphere of Mars: we have proof positive that Mars has an atmosphere; we have reason to believe this atmosphere to be very thin,--thinner at least by half than the air upon the summit of the Himalayas,--and in constitution, not to differ greatly from our own."

As to the existence of water on the planet, one has only to consider the polar snow caps. In the height of the southern winter, the polar cap of snow measures over two thousand miles across, covering fifty-five degrees of latitude, with one unbroken waste of white. As spring advances the snow begins to melt, disappearing rapidly as summer comes on, and, as it melts, a dark band is seen bordering this edge. As the snow recedes the dark band recedes. This band is, therefore, not a permanent marking on the planet, but obviously water, the result of the melting snow--an arctic sea, in fact. This band is irregular, varying in width in different longitudes, as if the water filled up large areas of depression. When finally the snow cap disappears, as it did for the first time on record on the notable occasion of October 13, 1894, the dark band, which had become thinner, disappeared also, leaving only a yellow stretch of surface. An additional proof that this dark band is water, was established by Professor W. H. Pickering, for he discovered that the light reflected from its surface was polarized. The absurdity of the suggestion that these white polar caps are not snow, but congealed carbonic acid gas, is fully shown by Lowell.

The asymmetry of the outline of these snow caps is paralleled by the irregularity of the Earth's polar caps. Glints of brilliant light are seen to flash out from this region, as if produced by sunlight reflected from a sloping surface. On comparing these flashes of light with observations made by Green, in 1877, they were found to be in the same place. Detached fields of snow were also observed below the receding line, an evidence that these regions were at a higher elevation. As before stated, on October 13, 1894, for the first time in the record of polar observations, the southern polar cap disappeared entirely. In this connection it may be of interest to observe that in the United States, in the summer of 1894, the temperature ranged a few degrees above the normal. (For this fact I am indebted to Professor Cleveland Abbe, E. S. M.)

The large, irregular, dark regions on the planet have been supposed to be bodies of water, or seas, and have been described and named as such by astronomers. Lowell shows, however, that there is every reason to doubt this conclusion. "To begin with, they are of every grade of tint,--a very curious feature for seas to exhibit, unless they were everywhere but a few feet deep; which, again, is a most singular characteristic for seas that cover hundreds of thousands of square miles in extent,--seas, that is, as large as the Bay of Bengal. The Martian surface would have to be amazingly flat for this to be possible. We know it to be relatively flat, but to be as flat as all this would seem to pass the bounds of credible simplicity. Here, also, Professor W. H. Pickering's polariscope investigations come in with effect, for he found the light from the supposed seas to show no trace of polarization. Hence, these were probably not water."

Lowell also shows that if these regions were seas, or water surfaces of the shallowest kind, sunlight would certainly be reflected from some portion of the surface so as to be visible from the Earth. A calculation of the region from which such a beam of light might be reflected has been carefully made, but no light of this nature has ever been seen. These regions change in color, and Schiaparelli suggested that in some way these changes were dependent on the Martian seasons. Lowell, by continuous observations covering many presentations of the planet, has demonstrated that the changes in color are synchronous with the seasons, and they further show that these regions change in expanse as well. The reader must refer to Lowell's book to understand the very minute way in which the author traces out the behavior of these so-called seas as the Martian summer advances and autumn comes on. His evidence is overwhelming that the regions heretofore regarded as seas are vast tracts of vegetation, doubtless on lower levels, or depressions of the surface, old sea bottoms, in fact, where springs and the natural settlings of stray waters might keep the ground sufficiently moist to support a scanty growth. The regions not marked by the dark shading, from their reddish and yellowish tinge, have always been regarded as land, probably desert land, as they remain fixed from year to year, dead and unchangeable as deserts are.