companion, with a smile, “and these names are convincing.”
[Illustration:
NO. 5. JULY 1, 1903; MOON’S AGE 6.24 DAYS.
]
“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.”
[Illustration:
NO. 6. NOVEMBER 26, 1903; MOON’S AGE 7.75 DAYS.
]
“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.”
[Illustration:
Lunar Volcano, in Section.
]
[Illustration:
Terrestrial Volcano, in Section.
]
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.’”
[Illustration:
NO. 7. JULY 2, 1903; MOON’S AGE 7.24 DAYS.
]
“Pardon me,” said my friend, “but it was not of names like those that I
was thinking. Observe how he who named the neighboring _Palus Somnii_,
‘Marsh of a Dream,’ exhibited an exquisite delicacy of fancy. It
suggests something indefinitely strange, romantic, imaginative. That
unknown astronomer, unknown at least to me, put a little of himself, a
little of his inmost mind, into the name, and I thank him for it. I
shall never forget the ‘Marsh of a Dream’ in the moon. It will haunt my
own dreams. I shall be all my life seeking and never finding its
meaning.”
“Since you are in so poetic a mood,” I responded, “I rejoice that
besides its bald facts, its fireless volcanoes, and its dried-up plains,
the moon possesses many things that can stir the imagination of the most
sentimental observer. But, in order that we may not wander too far from
the paths of science, let me recall your attention to the photograph. We
have been going over ground already trodden by returning to the
neighborhood of the _Mare Crisium_. I shall now lead you back to the
terminator, where we shall find a little that is new. Still nearly
hidden in night we perceive many great rings on which the sun is
beginning to rise, and four of the most important ranges of mountains
are coming into view. One of these, on the southern border of the _Mare
Serenitatis_, is visible throughout its entire extent. It forms a
portion of the coquettish ornaments with which the Moon Maiden has
decorated her hair, as we shall see clearly in the next photograph. This
range is named the Hæmus mountains. Near its center, quite at the edge
of the ‘sea,’ is a bright crater ring, one of the most conspicuous on
the moon. It is called Menelaus.”
“Menelaus?” exclaimed my friend. “Ah, then Riccioli did not confine his
favoritism to the astronomers and philosophers in putting their names in
the moon. Menelaus, if I remember my classical reading correctly, was
the husband of Helen of Troy.”
“Yes, the brother of Agamemnon himself. You must admit that Riccioli
occasionally felt his imagination a little awakened. He was not
altogether destitute of the spirit of poetry.”
“But did he also put Helen in the moon?”
“I am sorry to say that he did not. It would have been a very suitable
abode for her. However, if you like, you may recognize Helen in the Moon
Maiden herself.”
“Thank you, that will be, indeed, an unexpected pleasure.”
“Meanwhile allow me to point out to you that there is a curious light
streak, very faintly shown in the photograph, which crosses the _Mare
Serenitatis_ from Menelaus to the opposite shore, and reappears more
distinctly, on the lighter-colored plain toward the north. This streak
comes all the way from a great ring mountain named Tycho in the southern
part of the moon. It is more than 2,000 miles long, and is one of the
greatest mysteries of the lunar world. Tycho, which lies just on the
sunrise line, is not well seen in this photograph. It has a great number
of these strange streaks or rays proceeding from it in all directions.
We shall study them in one of the photographs which are to come. One
word in regard to the plain north of the _Mare Serenitatis_ of which I
have just spoken. It, too, has a name that is calculated to appeal to
your lively imagination. It is called the _Lacus Somniorum_, which if my
knowledge of Latin is correct, means ‘Lake of the Sleepers.’”
“Then your old friend Riccioli certainly did not bestow the
appellation.”
“No, it was one of his more fanciful, or, if you prefer, more poetical
predecessors, perhaps the same who imagined the ‘Marsh of a Dream.’”
“Oh, that gives me another reason to think of him with admiration and
gratitude. He, at least, had a soul that rose above mere prosaic facts.”
“Perhaps. But do not think too lightly of the facts of the moon. After
all the human mind must base itself upon the solid ground of fact.
Without that we should become mere dreamers, and be suited only to
inhabit your favorite ‘Marsh.’”
“The other mountain ranges of which I have spoken,” I continued, “are
faintly distinguishable eastward from the _Mare Serenitatis_. They are
the Apennines, the Caucasus, and the Alps. But perhaps we had better
turn at once to photograph No. 8 where they are much more clearly seen,
because the sunrise there has advanced a couple of hundred miles farther
east.”
“But, dear me, how slowly the sun rises on the moon! Was this photograph
taken a day later than the other?”
[Illustration:
NO. 8. AUGUST 31, 1903; MOON’S AGE 9.22 DAYS.
]
“Almost exactly two days later. When it was made the moon was nearly
nine and a quarter days old, and its age at the time No. 7 was made was
only seven and a quarter days. But, owing to the effects of libration,
an explanation of which I have put into a note for your private reading
when you feel like it, [see p. 57, footnote], the difference of phase
amounts to less than two days. You are right, however, in remarking that
sunrise is a very slow process on the moon. It requires about two weeks
to pass from the western side of the moon to the eastern side, and both
day and night at any point on the moon last about a fortnight. This
results from the fact that, as I have told you, the moon does not turn
rapidly on its axis like our own globe, but keeps always the same side
directed toward the earth. Accordingly, a lunar day and night are
together about a month long.”
“And was it so when, as I must persist in believing, there were
inhabitants on the moon?”