Part 5
“But if you should look at Endymion with a telescope you would wonder what the moon could find in him to admire. He has been turned into a huge, broken-walled ring plain. You will observe that the other, the southern or upper horn of the moon in the photograph, appears extraordinarily roughened. It is completely pitted with craters and rings. There are so many of them, and they are so entangled, that I shall not undertake to indicate them by their individual names, especially as there is none among them of the very first importance. If, however, you will bring your attention back to the _Mare Nectaris_ I shall be able to point out to you a very extraordinary object, which lies just on the border between day and night here, but will be seen in the next photograph that we examine, in full morning light. The object that I mean is a ring on the right-hand edge of the _Mare Nectaris_. Its eastern wall and the top of its central peak are brightly illuminated by the rays of the rising sun; while beyond it, to the eastward, everything, with the exception of the tips of one or two high peaks, is steeped in night. This is one of the mightiest volcanic formations that the moon contains. Its name is Theophilus. To see it and certain gigantic neighbors that it has, fully displayed, we shall turn, after this glance at its first appearance, to photograph No. 4.
“In this photograph the sunrise line on the moon has advanced so much farther eastward that the _Mare Nectaris_ lies well within the illuminated part of the disk, and Theophilus has become the most conspicuous object of the kind in view. You now observe that it does not stand alone, but is linked, so to speak, with another similar ring on its southeastern side, while still farther southward is a third less regular ring which seems to belong to the same group.”
“Oh, yes,” cried my companion, “they certainly do seem to be connected. They look like three links of an enormous broken chain dropped upon the moon.”
“The ring nearest to Theophilus,” I continued, “and whose northwestern side has been destroyed to give room for the full circle of the wall of Theophilus, is named Cyrillus. The other more distant one is Catharina. If you wish to become a little learned in the geography of the moon it is necessary that you should remember these names. As to the objects that the names designate, they are far too wonderful ever to be forgotten, and it is impossible to confuse them with any other features of the lunar world. There is a great deal of ‘history’ connected with these three enormous volcanic formations, but I am going to reserve that for a while, because by and by we shall examine a larger photograph of these same objects in which you will see their marvelous details displayed. Now let me direct your attention to the first chain of mountains that we have found upon the moon. Above Catharina you will notice a thin, crinkled line of light passing through a comparatively level district and ending at another ring. It is a range of peaks and cliffs named the Altai Mountains. They are of no great height, and cannot be compared in magnificence with the lunar Alps and the lunar Apennines which we shall see in the photographs taken a few days later, but they are nevertheless very interesting. The ring mountain at which the Altai range terminates is named Piccolomini. It is another marvelous object for telescopic study. The incomplete ring, with a dark interior, which forms the southern corner of the _Mare Nectaris_, resembling a semicircular bay, is Fracastorius. It is a very curious object because close inspection reveals that the missing part of its ring has been submerged, but is still faintly visible through the surface of the _Mare_.”
“I suppose it cannot be water that has covered it, since you have so often assured me that there is no water on the moon.”
“No, it is not water, but rock or sand or solidified lava, or some kind of solid matter. It looks as though the whole bed of the _Mare Nectaris_ had welled up in one mighty convulsive outpouring of liquid lava, which broke down the wall of Fracastorius, inundated the interior, and then hardened like a floor of cement. The probability that a catastrophe of the kind I have described has occurred here is heightened by the fact that the bed of the _Mare Nectaris_ is concave, sunken in the center, as if it had broken and settled down ‘like ice upon a pond.’ Scattered more or less all over its surface and particularly near its shores, there are indications of this breaking down, and of something that has been covered up.”
“To me it seems very mysterious,” said my friend, “and very terrible also.”
“It is more or less mysterious to the astronomer likewise. Still, geology shows that there have been somewhat similar occurrences on the earth. If you will now direct your eyes to the lower (northern) part of the photograph you will notice some additional things that have come into view with the advance of the sunlight. You observe that a vast somber region occupies the inner portion of the crescent below the center. This consists of two immense plains, one of which sends a large ‘bay’ as far south as the ring of Theophilus, where it is connected by a narrow ‘strait’ with the _Mare Nectaris_.
“Turning to photograph No. 5 we see the two plains to which I have referred more fully displayed. The sun has now risen over their entire surface. The upper one is the _Mare Tranquillitatis_, ‘Sea of Tranquillity’; and the lower one the _Mare Serenitatis_, ‘Sea of Serenity.’”
“I have always thought that astronomers must be happy persons,” said my companion, with a smile, “and these names are convincing.”
“Yes, perhaps, but then in bestowing the names they may have been transferring to the moon ideals of tranquillity and serenity which they did not find realized upon the earth. I am not going to talk about these two ‘seas’ at present because they are better represented upon one of the large photographs which we shall examine later. I prefer to direct your attention just now to some other things. In the first place look once more at Theophilus and its companion rings, and observe how they maintain their preëminence. The entire surface of the moon to the eastward and southward is broken and heaped up with mountains, craters, and rings, but nowhere do we see anything comparable with Theophilus except, perhaps, far toward the south, where near the inner border appear two still larger, but less regular, rings lying in line at a right angle to the terminator. The one on the left is Maurolycus, and the other, still half obscured by night, is Stöfler.”
“The names of old astronomers, I suppose.”
“Yes, astronomers sufficiently famous in their day, but who would be virtually forgotten at the present time if their friend Riccioli had not thus immortalized them. You see it is a great piece of good fortune to have your name in the moon. It is a kind of revenge for the neglect of future generations at home.”
“And it seems to me an equal good fortune to have had an admirer willing to set your name up in the moon.”
“Surely. But Riccioli’s own name is there also. Afterwards I shall show you his lunar monument, a truly magnificent one. Permit me now to tell you that Maurolycus is much greater in extent than any of the rings that we have yet seen. Not by any means so perfect in form as Theophilus, it covers a vast extent of surface, as much as 150 miles across, with an amazing mass of broken rings, walls, ramparts, ridges and chasms. Some of its peaks are 14,000 or 15,000 feet in height. It has a very lofty central mountain, visible in the photograph, and whose peak comes into view when the sun is rising long before the surroundings have been illuminated, so that it resembles a star glowing amid the blackest night. The neighbor of Maurolycus, Stöfler, is equally extensive and almost equally wild and magnificent when the sunlight is leaping across it from pinnacle to pinnacle and ridge to ridge. In this photograph, however, it is too near the terminator to be well seen. We shall presently pass to photograph No. 6, where Stöfler appears in full light, but before doing so let us glance at the northern part of the moon as here pictured. Close to the terminator, below the grand oval form of the _Mare Serenitatis_, you will perceive two rings, one above the other. They seem to be the complement of the other pair, Atlas and Hercules, which we looked at when the sun had recently risen upon them in another photograph, and which now appear far off toward the west. You observe that Atlas and Hercules lie upon an east and west line, and the others upon a north and south line. The northernmost one is named Aristoteles, and the other Eudoxus. They are situated near the edge of a plain called the _Mare Frigoris_, ‘Sea of Cold,’ thus named, I suppose, because it lies so far north. Aristoteles is about 60 miles in diameter, and its immense wall is very high and splendidly terraced. Eudoxus, equally deep, is only 40 miles in diameter.
“Turning to photograph No. 6, taken when the moon was more than a day older than it was when No. 5 was made, we have a striking example of the effect of libration in presenting the moon at perceptibly different angles to our line of sight at corresponding phases. We have now arrived at First Quarter, and behold all the western half of the moon illuminated by the sun. You will perceive that we now have in view, simultaneously, six of the great plains called ‘seas,’ namely, the _Mare Crisium_, the _Mare Fœcunditatis_, the _Mare Nectaris_, the _Mare Tranquillitatis_, the _Mare Serenitatis_, and the _Mare Frigoris_, while others are beginning to emerge out of night on the east. Maurolycus and Stöfler, the pair of giant rings in the south, are better seen than before because daylight has advanced farther across them. In fact Stöfler now appears more imposing than its great neighbor, and a smaller ring breaking the continuity of its wall on the western side is visible. Above these, in the direction of the south pole of the moon, and around the pole itself, the surface is marvelously rough and broken. It looks as if it would be impossible to find a level acre of ground in all that region. The rings and craters are veritably innumerable. It is the existence of these irregularities which causes the terminator to appear so crooked and broken. At some places you perceive small bright points within the edge of the night half of the moon. These, of course, are the summits of peaks, which have just been touched by the sunlight while the surface all around them is still covered with darkness.
“Below Stöfler, all along the terminator, as far as the middle of the moon, an irregular row of rings appears. Three of these bear some resemblance to the great group of which Theophilus is the chief member. They are, counting from south toward north, Aliacensis, Werner, and Blanchinus. Below them two other much larger ones are conspicuous, Albategnius, the more southerly, and Hipparchus. These two are full of moon history. Albategnius, the smaller, is very deep and comparatively perfect in condition, while Hipparchus, more than 90 miles across, has been vividly described as a ‘wreck and ruin,’ its walls, once possibly of great height, being now low and broken, and traversed with gaps and valleys, while a great cleft exists crossing a part of the broad, irregular floor. It is probable that Hipparchus is an older formation than Albategnius.”
“Pardon me,” interrupted my companion, “but I must cry for mercy. Really, these strange names escape from my mind as fast as you mention them. Is there not something a little more romantic in the moon—something to relieve the strain of all this nomenclature of words terminating in ‘us,’ and this frightful lunar geology?”
“Yes,” I said, “I believe that on the other half of the moon, which has not yet seen the sun rise, we shall find something better to your taste. But do not be too impatient. Reflect that these names represent very wonderful things visible to us in another world than ours, things the knowledge of which has cost the lifelong labors of many gifted men, and that will be remembered, studied, talked, and written about centuries after we are dead. Fortunately for your powers of attention the eastern half of the moon, upon which day will be seen gradually dawning in the next set of photographs, has a general character quite different from that of the western half. It contains the greatest ranges of lunar mountains, yet upon the whole it is more level, being covered to a great extent with broad plains, in the midst and along the borders of which stand the most remarkable and interesting of all the lunar formations. In and around some of them we shall search for the evidences which some astronomers think that they have found of life upon the moon.”
“Oh, that indeed will be interesting!” exclaimed my friend with reviving animation.
“But,” I added, “do not place your expectations too high. Keep your imagination under control, try always to be just a little ‘scientific’ in your way of looking at things, and then I believe you will not be disappointed.”
“Oh, please do not think that I have been disappointed,” she said deprecatingly. “But positively you must admit that ‘Albategnius,’ ‘Aliacensis,’ ‘Blanchinus,’ and ‘Maurolycus,’ are not precisely captivating. Remember that I have read little except poetry and romance, and those histories that are full of stories.”
“You will find a deep vein of poetry and romance in the moon,” I replied, “before we have finished, and after you have reflected upon what we have seen and what we have been saying.”
Leaving the remaining photographs to be examined after lunch, we now entered the house.
II
FIRST QUARTER TO FULL MOON
II
FIRST QUARTER TO FULL MOON
NOTWITHSTANDING the signs of impatience which my friend had manifested when we were passing, in our review of the photographs, from one lunar ring mountain to another, all more or less similar in appearance and characteristics, I was gratified to see that her mind was still attracted to the subject of the moon, and during the lunch she, of her own accord, began to talk of it.
“You have said so much about volcanic occurrences on the moon,” she remarked, “that I wonder why you do not call those immense mountains ‘volcanoes.’ I observe that you always speak of them as ‘rings,’ or ‘mountain rings,’ or ‘ring plains’; while to me, although to be sure I am no geologist and have perhaps no right to an opinion, they seem plainly to be just huge volcanoes and nothing else.”
“Your observation is quite correct,” I replied, “as far as superficial appearance goes, and I may add that these great rings are often called volcanoes. If we apply the proper adjective and name them ‘lunar volcanoes,’ perhaps there can be no objection to the term. But they are certainly widely different from our terrestrial volcanoes. The difference is not in size alone, although in that regard it is enormous. There is a far more significant difference, which you could hardly be expected to notice in a simple inspection of the photographs, although it is evident when once pointed out. I refer to the fact that what seem to be the craters of lunar volcanoes are not situated on the tops of mountains. They are immense plains, more or less irregular in surface, and often having a peak or a group of peaks in the center, while around these plains always extends a mountain ring, steep on the inner side, and having a gradual slope without. But most significant fact of all, the plains, or floors inside the ring, are almost invariably situated thousands of feet below the general level of the moon. If the terrestrial volcanoes were formed on the plan of the lunar ones, when we visit Vesuvius, instead of climbing up a mountain rising out of the midst of a plain and capped with a cone, having a funnel-shaped crater in the center, we should find before us a relatively low, circular elevation, on surmounting which there would appear on the inside of the circle a great basinlike hollow, far below the level of the surrounding country. In the center of this, distant from the lofty encircling walls, would be seen a conical hill with smoke and vapor issuing from a vent at its summit. The top of this crater hill would be lower than the rim of the basin-shaped hollow, so that the whole volcano with its immediate surroundings would be inclosed and shut off from the environing upper world by the sides of the basin. While you finish your coffee I will make a sketch which may render this difference between lunar and terrestrial volcanoes evident at a glance.”
Accordingly, after a few minutes, I presented to her these two diagrams, remarking that it should be borne in mind that the two sketches were not made on the same relative scale. “I was compelled,” I said, “to change the true proportions in the section of the lunar volcano, for if I had drawn them as they are in fact, the width of the basin would have been enormous in proportion to its depth. You will recall that I told you that such rings as Albategnius and Maurolycus are a hundred miles and even more in diameter, while their depth does not exceed two or three miles. It results from this necessary falsification of proportions in the sketch that the terrestrial volcano, although so widely different in form, appears comparable in magnitude with the lunar one. But the fact is that you could take a dozen of the largest volcanic mountains on the earth and throw them into one of the great lunar rings without filling it.”
“I am the more astonished by what you say,” remarked my friend, “because you have already told me that the moon is so much smaller than the earth. How does it happen, then, that her volcanoes are so much larger? I should think that in a little world all things would be small in proportion.”
“It is quite natural to think so,” I replied, “until you reflect upon the consequences of the smaller force of gravitation on a small world. I told you last evening that gravitation on the moon, is only one sixth as powerful as it is on the earth, and you will recall that one consequence which I pointed out was that you would weigh only twenty pounds if you were on the moon. Since the same reasoning applies to all objects in the lunar world, it is clear that a similar force exerted there would be able to produce enormously greater effects, as for instance in the formation of vast hollows or depressions, by violent explosions, the products of which would be thrown to immense distances. Some selenographers, which is a term applied to those who study the features of the lunar world, have suggested that in this cause alone is to be found the explanation of the giant lunar ring mountains. At some remote period of the past, according to them, the volcanic forces of the moon reached a maximum of activity and energy. The lava, cinders, ashes, and other products of ejection, were hurled to a height of scores of miles, and when this fell back at a great distance from the centers of eruption these were piled up in huge rings, fifty, eighty, or a hundred miles in diameter, while the surface of the moon within the rings sank in consequence of the withdrawal of the material thus ejected. To account for the existence of the central mountains so often found in the middle of the rings, it has been suggested that at a much later period, when the volcanic energy had become comparatively insignificant, as a result of the cooling of the interior of the moon, less violent explosions, not greater than many that have occurred on the earth, took place, and by these the central peaks were formed.”
“You are going to think me too romantic, or too imaginative, again,” said my friend, with a smile, “but I cannot prevent myself from wondering what the inhabitants of the moon did and thought while all those marvelous things were happening.”
“I have not said that there were inhabitants of the moon.”
“No, but you have confessed that there might have been inhabitants, some time, and I should like to know whether they were there when those terrible volcanoes were formed.”
“If they were,” I replied, “they could not have survived such a universal upheaval as the surface of the moon has undergone. You have seen in the photographs that the great rings and smaller craters are scattered thickly over the moon. It is true that comparatively few are found in the level expanses called ‘seas,’ but if those regions were covered with water they could only have been inhabited by beings provided with gills and fins.”
“How long ago did these explosions occur?”
“I cannot tell you, except that it must have been many ages in the past; so long ago, indeed, that the whole course of human history seems but a day in comparison.”
“Then,” said my friend with animation, “there has been time enough _since_ that dreadful period for inhabitants to develop upon the moon, has there not?”
“Yes, time enough, perhaps, provided that sufficient water and air and other vital requisites remained after the exhaustion of the volcanic energies.”
“Oh, let us say that they did remain. I am eager to believe that the moon has not always been so desolate as she appears at present.”
“Very well, you are at liberty to believe that if you like. No astronomer is likely positively to contradict you, although he may smile a little incredulously. Besides, as I have already told you, there are certain rather inconclusive indications of some kind of life, and of some kind of activity, still on the moon.”
“Please show them to me, then, or tell me about them. Perhaps I shall find them less inconclusive than you do.”
“Everything in its turn,” I replied. “We shall come to the indications that I have spoken of after we resume the inspection of the photographs.”
“Then I am ready to resume at once.”
Accordingly we returned to the table and the photographs under the pleasant shade of the elm. Taking up the photograph numbered 7, I remarked that it exhibited the moon as it appears a little after First Quarter; that is to say, a trifle more than half the face turned toward the earth is in the sunlight. I called attention once more to the six “seas,” which we had already remarked, and to the continued conspicuousness of Theophilus and its companions, a little above the middle of the visible hemisphere.
“You observe now,” I continued, “how the rotundity of the lunar globe begins to manifest itself as the sunlight sweeps farther eastward. The crescent shape is gone and the line between day and night begins to be bowed outward, convexly. The _Mare Crisium_ is particularly well defined, and also the diamond-shaped region called the _Palus Somnii_. With the sun so nearly vertical above it, the remarkable peak of Proclus, between the _Palus Somnii_ and the _Mare Crisium_, has become very brilliant. In a telescope you would see it glowing almost like a star. You observe also that several long, straight, bright rays proceed from it in several directions.”
“All the more reason, it seems to me,” said my friend, “why your unimaginative astronomer, Riccioli, should have named it for some brilliant gem instead of attaching to so dazzling an object the prosaic designation of ‘Proclus.’”
“After all,” I replied, “what’s in a name?” Now that you are familiar with the appearance of Proclus, its name will henceforth call up to your mind an image as brilliant as if it had been named ‘Mount Diamond’ or ‘Mount Amethyst.’”