the greatest telescopes, with their highest powers, are unable to bring
the moon within less than an apparent distance of say forty miles. At
such a distance it is manifestly impossible to tell of what a lunar
formation consists. We cannot analyze the moon with the spectroscope as
we can the sun and the stars, because she does not shine with her own
inherent light. We can only infer that a large part of the substance of
Aristarchus consists of something which reflects a very great proportion
of the light that falls upon it. If a mountain on the earth were
composed of a vast mass of crystals, or of bare polished metal, we might
expect it to present, when seen from the moon, some such appearance as
we notice when we look at Aristarchus.
“In this photograph the _Sinus Iridum_, having the sun higher above it,
is more brilliantly illuminated than in No. 10. Particularly you will
notice the brightness of the line of cliffs along its eastern curve,
terminating at the promontory of Heraclides.”
“That is the promontory which presents the profile of a woman’s face, if
I recall correctly what you told me.”
“Yes. Please observe also that the oval of Plato is as dark as ever,
while Copernicus has, if possible, increased in brightness, and the
great splatter of broken rays around it seems to have extended farther
over the surrounding maria. Almost directly east of Copernicus, in the
_Oceanus Procellarum_, appears a much smaller crater ring, Kepler, which
resembles a miniature of Copernicus because it, too, is encircled with a
kind of corona of short, bright rays. Copernicus, Kepler, and
Aristarchus mark the corners of a large triangle. Speaking of rays
recalls us to Tycho. You will see that, as I told you, this wonderful
formation grows in relative prominence when the period of Full Moon
approaches. Its ringed wall and central mountain are obscured by their
own brilliance, while the gigantic system of bright bands, or rays,
which have their center of origin at Tycho, is gradually becoming the
master feature of the bright part of the moon.
“I have told you that the _Mare Humorum_, which is very sharply defined
in the picture before us, is the darkest of all the level areas that go
under the name of ‘seas.’ It is not, however, the darkest _spot_ on the
moon. There are several places where the surface appears, at times, much
duskier than in any part of the _Mare Humorum_. Three or four of these
are clearly discernible in this photograph. They lie westward from
Copernicus in the _Sinus Medii_, the _Sinus Æstuum_, and the _Mare
Vaporum_. Their dusky hue strikes the eye at once. They give the
impression of sink holes. No special name is attached to them, but they
must have been evident to the first observers, with the smallest
telescopes, and it is rather surprising they should have escaped special
designation on the lunar charts. A fact which will especially interest
you is that some observers look upon these and other dusky areas on the
moon as being, possibly, indications of the existence of some kind of
vegetation there.”
“But if there is vegetation there may be other kinds of life also, may
there not?”
“Ah, I have not said positively that there _is_ vegetation, but _if_
there is then your conclusion as to other life may be correct. Glance
next at the upper part of the disk along the terminator. Two or three
broad oval rings have come into view there. The largest of these with
its long eastern wall lying exactly on the line between day and night is
an extremely interesting formation, bearing the name of Schickard. The
plain within the ring is almost large enough to have been called a ‘sea’
or at least a ‘lake.’ It is about 134 miles in diameter, and is in
reality much more nearly circular than it appears to be. Like all
similar formations situated near the ‘limb’ of the moon, by which we
mean the edge as viewed from the earth, it is greatly foreshortened by
perspective. The scale of the photograph is, unfortunately, not large
enough to reveal an unique thing in the immediate neighborhood of
Schickard, toward the southeast. I refer to what, as far as its
telescopic appearance goes, might be described as an enormous bubble—a
bubble 54 miles in diameter. Unlike the other formations the surface of
this singular ring is elevated above the general level of the moon. When
we come to examine it in detail it hardly answers, perhaps, to my
designation of a bubble, since the edges are a little higher than the
center, giving it the form of a shallow dish. If we could visit it we
should find on approaching that we were climbing the slopes of what
would seem to be a chain of low mountains, and on reaching the summit we
should see before us an elevated circular plain, sinking gradually
toward the middle. Filled with water it would form a shallow lake lying
on the top of a broad, flat mountain. There is nothing else quite like
it on the moon and certainly nothing on the earth.”
“It must have been a great curiosity in the days when the moon was
inhabited, and I suppose that scientific ‘lunarians’ organized
expeditions to explore it.”
“Perhaps, if you choose to regard it in that way. Now look again at the
_Mare Humorum_. You perceive that its eastern side is lined with
mountains and crater rings, while near the center of the northern border
there is a conspicuous ring with a bright line running from the southern
edge to the center. This is one of the most beautiful of lunar
formations, and is named Gassendi. It is a favorite object for those who
study the moon with telescopes on account of the great variety and
singularity of the details visible within the ring. When you become a
selenographer and possess your own telescope you will find few things
more interesting to study than Gassendi.
“Next let us take up photograph No. 12. Here the moon is once more a
little ‘older’ than before, and the sunrise line has again advanced a
little eastward. This advance does not appear so rapid when the
terminator is near the moon’s limb, because, on account of the rounding
away of the lunar globe, the illuminated surface is foreshortened from
our point of view on the earth. In this photograph you perceive that the
wonderful shining mountain Aristarchus has become even brighter than it
was before, or at least it is more conspicuous on account of the
appearance of what seems to be a short ray shooting out from it in a
southeasterly direction. There is also a light spot just below it which
is caused by a little mountain group called the Harbinger Mountains. The
bright ray connects Aristarchus with its neighbor Herodotus, of which I
spoke a little while ago. There is a very remarkable feature of the moon
here, not shown in the photograph, but to which I must briefly refer. It
is an enormous cleft, or crack, or, if you please, cañon, which starts
from Herodotus, whose northern wall seems to have been broken through to
give passage to it, and goes winding across the surface of the _Oceanus
Procellarum_ with several sharp turns and angles for a total distance of
nearly a hundred miles. What produced this remarkable chasm on the moon
it is difficult to say. Some have suggested that it may once have been
the bed of a river, but there are many serious objections to that view.
Nevertheless, there seems to be little doubt that if we were to visit
the moon we should find, in many ways, a striking resemblance between
this prodigious cañon and that of the Colorado River.”
“And are not all these things so ancient, as far as you can tell, that,
like the terrible volcanic rings, they might have been formed before the
appearance of inhabitants upon the moon?”
[Illustration:
NO. 12. SEPTEMBER 4, 1903; MOON’S AGE 13.27 DAYS.
]
“They certainly seem to be very ancient, and I cannot deny the
_possibility_ of what you say.”
“Very well, then, I, for my part, am convinced that curious eyes, filled
with the light of intelligence, have peered down from the verge of that
chasm into its fearful depths. If you will not permit me this flight of
imagination I shall refuse to take any further interest in the moon.”
“Oh, I should not think of refusing. Imagine what you will, and draw
your own inferences, only remembering that they are not supported by
_ascertained_ facts, and probably never will be. Yet for all that they
may have an element of truth.”
“Pardon me for saying that your astronomical science, as far as it
concerns the moon at least, does not seem to me quite satisfying. You
are not bold enough in drawing conclusions.”
“On the contrary many astronomers think that some of their brethren are
altogether too bold in that respect. However, it must be freely
confessed that astronomical science, except perhaps in its mathematics,
is not satisfying even to those who have created it. Nobody would
rejoice more sincerely than the astronomer at the discovery of evidence
of the former, or even the present, habitability of the moon. It is
surely a great disappointment that we have not been able to settle so
apparently simple a question in regard to our nearest neighbor in the
sky.”
“Then if I were a multimillionaire I should certainly devote several of
my millions to the construction of a telescope great and powerful enough
to reveal so interesting a secret.”
“With your great telescope you could probably render possible many
discoveries at present beyond our reach. But the mightiest telescope
that you could make would enable no one to _see_ inhabitants on the
moon, even if they existed.”
“Not if it magnified the moon a million times?”
“No, for optical imperfections and the disturbances to clear vision
produced by our atmosphere would absolutely prohibit the use of any such
magnification. And even supposing that one could use a magnifying power
of 1,000,000 diameters in viewing the moon, how near do you think that
would place us to the lunar surface? It would still appear to be more
than a quarter of a mile away.”
“That is not much. I am sure I can see people at that distance.”
“Oh, yes, but the distinctness of view would be nothing like so great as
if you were looking at the same objects on the earth. Still, if we could
obviate the atmospheric and other difficulties, a magnifying power of
one million would certainly enable us to discover the works of the
moon’s inhabitants—their houses, their fields, their plantations, their
great establishments of art and industry. But I assure you that a
telescope of such power is a mere dream. It could never be constructed
without some fundamentally new and unheard-of discovery in optics. We
shall do better to turn once more to our photographs which, at least,
have no deceptions. Dropping No. 12, we shall take up No. 13, which
brings us practically to the Full Moon phase. The moon’s age at the time
this photograph was made was nearly fourteen and one-half days. You see
that its whole eastward face is now lying in the sunlight. The march of
day across its surface has been completed, and on the western edge of
the moon the sun is about to set, while on the eastern edge it is just
rising. Among the new things that have come into view is a conspicuous
dark oval, shaped like Plato, but very much larger, near the eastern
edge. This is a walled plain named Grimaldi, and it enjoys the
distinction of being the darkest on the moon. Near it on the northeast
and consequently closer to the limb is another walled plain, which I
promised some time ago to point out to you because it bears the name of
the astronomer Riccioli, the great bestower of names on the moon, and
upon whose lack of imagination you have so severely commented. But, as
you have already learned, the time of Full Moon is not the best for
studying the mountains and rings, because then the light strikes too
nearly vertical upon them and they cast no shadows. But it is the best
time for seeing the broad general features of the lunar surface. Turn
the picture upside down again, thus bringing the disk into its natural
position as seen with the naked eye, and this photograph shows the moon
very much as it appears with a small pocket telescope, or with a
powerful binocular. The new prism binoculars that have come into use
within the past few years are excellent for general views of the moon.
Their defining powers are superb, and one who has never seen the moon
with such a glass is always greatly surprised and delighted with the
view which it affords. You see now that Tycho forms a blazing brooch,
resting on the Maiden’s neck, while its rays extend across her profile,
and the long one lying over the _Mare Serenitatis_ bears some
resemblance to a pin displayed in her hair, with the crater ring,
Menelaus, glittering at its lower end. The other bright point, to the
left of Menelaus (we will henceforth keep the picture reversed), is a
ring mountain named Manilius. After the detailed study which we have
given to the various ‘seas’ and formations you should be able to
recognize them with the picture in this position, and I wish that you
should do so because, as I have just remarked, this is the position of
the Full Moon as it is always seen with the naked eye or with a simple
binocular, for the latter does not reverse it, as does a telescope. The
western edge is now at the right hand, and the north at the top. All the
_mares_ are clearly visible. On the right the _Mare Crisium_, the _Mare
Fœcunditatis_, the _Mare Nectaris_ and the _Mare Tranquillitatis_; in
the center, above, the _Mare Serenitatis_; on the left the _Mare
Imbrium_, the _Mare Vaporum_, the _Mare Nubium_, the _Mare Humorum_, and
the _Oceanus Procellarum_. The two bright spots on the right, lower than
the _Mare Fœcunditatis_, are Petavius and a neighboring ring. Vendelinus
forms a less brilliant spot at the western edge of an extension of the
_Mare Fœcunditatis_, and Langrenus is distinctly seen on the western
shore of the main body of that _mare_. Proclus and the remarkable
diamond of the ‘Marsh of a Dream’ are very plain just under the large
oval of the _Mare Crisium_. The mountains and cliffs encircling the
_Mare Imbrium_ on the west, north, and east you will recognize at a
glance. The dark Plato is conspicuous in the lighter mountainous area
north of this ‘sea,’ and the semicircle of the ‘Bay of Rainbows’ is
sharply defined. Farther north is the long, dark _Mare Frigoris_, whose
eastern end merges into the broad _Oceanus Procellarum_. Aristarchus
appears as a very bright point in this ‘ocean,’ and far to the right of
Aristarchus, toward the center of the disk, Copernicus, with its
splatter of irregular rays, is conspicuous. Following the eastern limb
round toward the south we see again the dark oval of Grimaldi, beyond
which the bright mountainous region broadens as we approach the South
Pole.
[Illustration:
NO. 13. SEPTEMBER 5, 1903; MOON’S AGE 14.40 DAYS.
]
“There is just one other thing on which I should like to dwell a little
while we have the Full Moon before us. I have already referred to it
once or twice—I mean the system of bright rays or bands radiating from
Tycho. These rays, as I have told you, are among the greatest mysteries
of the moon. Their appearance is so singular and, if I may so describe
it, unnatural, that when the first photographs of the Full Moon were
published, some persons actually thought that they were being imposed
upon. They imagined that the photographer had indulged in a practical
joke, by photographing a peeled orange and dubbing it ‘the moon.’ The
mysterious rays do not start from the central mountain of Tycho, nor
even from the ring itself, but from a considerable distance outside the
ring. Nevertheless, Tycho is manifestly the center from which they
arise. It looks as though some irresistible force had been focused at
that point—a force that split the moon along a hundred radiating lines.
This is, in substance, the theory of the English selenographer Nasmyth.
He supposed that, the lunar globe being burst by internal stress, molten
lava welled up and filled the cracks. After solidifying this lava
possessed a lighter color and greater reflecting power than its
surroundings and thus gave rise to the appearance of long bands.”
“Really, your moon history seems to me to be made up of extremely
tragical chapters. But I am content as long as you put all these
terrific events sufficiently far in the past to leave time for the moon
to have enjoyed a different kind of history since they occurred.”
“But,” I said, “even if I grant what you wish, you must admit that the
greatest tragedy of all succeeded.”
“What do you mean?”
“I mean simply that your imagined lunar age of gold, when the moon was
full of animated existences and beautiful scenes, has also become a
thing of the past; and what geological cataclysm can be compared in
tragic intensity with the disappearance of a world of life?”
“But that disappearance was gradual, was it not?”
“Very likely it was, if it depended upon the slow withdrawal of the
atmosphere and water.”
“Good! Then again I am fairly well content, for all things must have an
end. The most beautiful life finally merges into old age and death. I
think I have read that some of your _savants_ predict that the earth
will not always be a living world. All that I ask is that you leave room
somewhere in your lunar history for an age of life on the moon.”
“Very well then. As I have told you several times, Science does not
positively forbid you to picture such an age if you will. She only says
that she cannot find the evidences of its existence. Still, as we are
going to see later, there are those who think that they can perceive
indications of some simple forms of life on the moon even now. I will
grant you that in the past these may have been more numerous and more
highly organized.”
By this time the afternoon had waned and the trees were lengthening
their shadows upon the lawns of the park.
“Perhaps,” I said, “we had better postpone an examination of the
remaining photographs of the series exhibiting the moon’s various phases
until after dinner. They will show very well in the light of the
electric chandelier. I have but a few words to add concerning the rays
of Tycho. The opinion of Nasmyth concerning their mode of origin has not
been universally accepted. Prof. William H. Pickering, for instance, has
suggested that the rays are formed by some whitish deposit from the
emanations blown out of comparatively minute craters lying in rows. He
supposes large quantities of gas and steam given forth from craters
surrounding the rim of Tycho, and, in consequence of these gases and
vapors being absorbed and condensed in more distant regions, a wind
constantly blowing away from Tycho and distributing the white deposit in
windrows. A similar explanation has been applied to the shorter and more
irregular systems of rays surrounding Copernicus, and a few other ring
mountains.”
“I prefer the Nasmyth hypothesis,” said my friend, as we rose and took
the path to the house. “It is, to be sure, more gigantically tragic, but
then it is simpler and more easily comprehended.”
------------------------------------------------------------------------
III
FULL MOON TO OLD MOON
------------------------------------------------------------------------
III
FULL MOON TO OLD MOON
AFTER dinner, in the brilliantly lighted drawing-room, we once more
spread out the photographs on a table.
“This time,” I said, taking up No. 14, “we are going to watch the
advance of night over the moon. Before, it was the march of sunrise that
we followed. Both begin at the same place, the western edge or limb of
the moon. Comparing this photograph, which was taken when the moon was
about fifteen and two-third days old, with No. 13, taken when the moon’s
age was more than a day less, you perceive, at a glance, wherein the
chief difference lies. In No. 13 sunrise is just reaching the eastern
limb; in No. 14 sunset has begun at the western limb. Having watched day
sweep across the lunar world, we shall now see night following on its
track. West of the _Mare Crisium_ and the _Mare Fœcunditatis_, which I
expect you to recognize on sight by this time, darkness has already
fallen, and the edge of the moon in that direction is invisible. The
long, cold night of a fortnight’s duration has begun its reign there.
The setting sun illuminates the western wall of the ring mountain
Langrenus, which you will remember was one of the first notable
formations of the kind that we saw emerging in the lunar morning. But
then it was its eastern wall that was most conspicuous in the increasing
sunlight. For the selenographer the difference of aspect presented by
the various objects of the lunar world when seen first under morning and
then under evening illumination is extremely interesting and important.
Many details not readily seen, or not visible at all, in the one case
become conspicuous in the other. But it is only close along the line
where night is advancing that notable changes are to be seen. Over the
general surface of the moon there is not yet any perceptible change,
because the sunshine still falls nearly vertical upon it. Tycho’s rays
are as conspicuous as ever. Aristarchus, away over on the eastern side,
is, if possible, brighter than before, and the three small dark ovals,
Endymion a little west of the north (or lower) point, Plato at the edge
of the _Mare Imbrium_, and Grimaldi near the bright eastern limb, are
all conspicuous.”
[Illustration:
NO. 14. AUGUST 26, 1904; MOON’S AGE 15.65 DAYS.
]
“But look!” exclaimed my friend, putting her finger upon the photograph.
“Here is something that you have not mentioned at all. I believe that I
have made a discovery, although you probably will not accept it as a
scientific one. I see here a dark woman in the moon.”
“I confess,” I replied, “that I am not acquainted with her, and do not
even see her. Please point her out to me.”
“She appears in profile, like the brilliant Moon Maiden, but is not so
much of a beauty. In fact I begin to suspect that she is the ‘Old Woman
in the Moon,’ that I have often heard of.”
“Positively I do not see her.”
“Then I will try to recall some of the names that you have been telling
me in order to indicate where you should. She faces west and occupies
most of the eastern half of the disk. Her head is under Tycho, toward
the northeast, I suppose you would say. The bright double ray that you
pointed out in one of the preceding pictures lies across the top of her
head and over her ear. Her face seems to be formed by a part of the
_Mare Nubium_—you observe how well I have learned your selenographical
terms—and her hooked nose is composed of a kind of bay, projecting into
the bright part below Tycho. Her front hair is banged, and the _Mare
Humorum_ constitutes her chignon. She has a short neck, and a humped
back, consisting of the _Oceanus Procellarum_. Copernicus resembles a
starry badge that she wears on her breast, and Aristarchus glitters on
the inner side of the elbow of her long arm. The _Mare Imbrium_ seems to
be a sort of round, bulky object that she carries on her knee, and she
appears to be gazing with intentness in the direction of the _Mare
Tranquillitatis_.”
“Ah, yes,” I said, laughing, “I see her plainly enough now. I really
cannot say that your discovery is likely to be recorded in astronomical
annals, but nevertheless I congratulate you upon having made it, if only
for the reason that henceforth you can never forget the names and
locations of the lunar ‘seas’ and other objects that you have been
compelled to remember in pointing out your ‘dark woman.’ In truth, her
features are almost as well marked as those of the Moon Maiden, but you
will hardly be able to find her again, except in a photograph, or with
the aid of a telescope, because you must recollect that this picture
shows the moon reversed top for bottom as compared with her appearance
to the naked eye, or with an opera glass. But please look again at the
objects along the western edge, for we are about to turn our attention
to photograph No. 15 in which this will be no longer visible. You must
say ‘good-by,’ or rather ‘good night,’ to the _Mare Crisium_ and the
_Mare Fœcunditatis_; for you will see them no more, until another lunar
day has dawned.”
We next picked up photograph No. 15.
[Illustration:
NO. 15. AUGUST 28, 1904; MOON’S AGE 17.41 DAYS.
]