THE PLANETS
_A._--MERCURY, VENUS, THE EARTH, MARS
And now we are in the Solar System, at the center, or, better, at the
focus of which burns the immense and dazzling orb. We have appreciated
the grandeur and potency of the solar globe, whose rays spread out in
active waves that bear a fecundating illumination to the worlds that
gravitate round him; we have appreciated the distance that separates the
Sun from the Earth, the third of the planets retained within his domain,
or at least I trust that the comparisons of the times required by
certain moving objects to traverse this distance have enabled us to
conceive it.
We said that the four planets nearest to the Sun are Mercury, at a
distance of 57 million kilometers (35,000,000 miles); Venus, at 108
million (67,000,000 miles); the Earth, at 149 million (93,000,000
miles); and Mars at 226 million (140,000,000 miles). Let us begin our
planetary journey with these four stations.
MERCURY
A little above the Sun one sometimes sees, now in the West, in the
lingering shimmer of the twilight, now in the East, when the tender
roseate dawn announces the advent of a clear day, a small star of the
first magnitude which remains but a very short time above the horizon,
and then plunges back into the flaming sun. This is Mercury, the agile
and active messenger of Olympus, the god of eloquence, of medicine, of
commerce, and of thieves. One only sees him furtively, from time to
time, at the periods of his greatest elongations, either after the
setting or before the rising of the radiant orb, when he presents the
aspect of a somewhat reddish star.
This planet, like the others, shines only by the reflection of the Sun
whose illumination he receives, and as he is in close juxtaposition with
it, his light is bright enough, though his volume is inconsiderable. He
is smaller than the Earth. His revolution round the Sun being
accomplished in about three months, he passes rapidly, in a month and a
half, from one side to the other of the orb of day, and is alternately a
morning and an evening star. The ancients originally regarded it as two
separate planets; but with attentive observation, they soon perceived
its identity. In our somewhat foggy climates, it can only be discovered
once or twice a year, and then only by looking for it according to the
indications given in the astronomic almanacs.
[Illustration: FIG. 32.--Orbits of the four Planets nearest to the Sun.]
Mercury courses round the Sun at a distance of 57,000,000 kilometers
(35,000,000 miles), and accomplishes his revolution in 87 days, 23
hours, 15 minutes; _i.e._, 2 months, 27 days, 23 hours, or a little less
than three of our months. If the conditions of life are the same there
as here, the existence of the Mercurians must be four times as short as
our own. A youth of twenty, awaking to the promise of the life he is
just beginning in this world, is an octogenarian in Mercury. There the
fair sex would indeed be justified in bewailing the transitory nature of
life, and might regret the years that pass too quickly away. Perhaps,
however, they are more philosophic than with us.
[Illustration: FIG. 33.--Orbits of the four Planets farthest from the
Sun.]
The orbit of Mercury, which of course is within that of the Earth, is
not circular, but elliptical, and very eccentric, so elongated that at
certain times of the year this planet is extremely remote from the solar
focus, and receives only half as much heat and light as at the opposite
period; and, in consequence, his distance from the Earth varies
considerably.
[Illustration: FIG. 34.--Mercury near quadrature.]
This globe exhibits _phases_, discovered in the seventeenth century by
Galileo, which recall those of the Moon. They are due to the motions of
the planet round the Sun, and are invisible to the unaided eye, but with
even a small instrument, one can follow the gradations and study Mercury
under every aspect. Sometimes, again, he passes exactly in front of the
Sun, and his disk is projected like a black point upon the luminous
surface of the flaming orb. This occurred, notably, on May 10, 1891, and
November 10, 1894; and the phenomenon will recur on November 12, 1907,
and November 6, 1914.
Mercury is the least of all the worlds in our system (with the exception
of the cosmic fragments that circulate between the orbit of Mars and
that of Jupiter). His volume equals only 5/100 that of the Earth. His
diameter, in comparison with that of our planet, is in the ratio of 373
to 1,000 (a little more than 1/3) and measures 4,750 kilometers (2,946
miles). His density is the highest of all the worlds in the great solar
family, and exceeds that of our Earth by about 1/3; but weight there is
less by almost 1/2.
Mercury is enveloped in a very dense, thick atmosphere, which doubtless
sensibly tempers the solar heat, for the Sun exhibits to the Mercurians
a luminous disk about seven times more extensive than that with which we
are familiar on the Earth, and when Mercury is at perihelion (that is,
nearest to the Sun), his inhabitants receive ten times more light and
heat than we obtain at midsummer. In all probability, it would be
impossible for us to set foot on this planet without being shattered by
a sunstroke.
Yet we may well imagine that Nature's fecundity can have engendered
beings there of an organization different from our own, adapted to an
existence in the proximity of fire. What magnificent landscapes may
there be adorned with the luxuriant vegetation that develops rapidly
under an ardent and generous sun?
[Illustration: FIG. 35.--The Earth viewed from Mercury.]
Observations of Mercury are taken under great difficulties, just because
of the immediate proximity of the solar furnace; yet some have detected
patches that might be seas. In any case, these observations are
contradictory and uncertain.
Up to the present it has been impossible to determine the duration of
the rotation. Some astronomers even think that the Sun's close proximity
must have produced strong tides, that would, as it were, have
immobilized the globe of Mercury, just as the Earth has immobilized the
Moon, forcing it perpetually to present the same side to the Sun. From
the point of view of habitation, this situation would be somewhat
peculiar; perpetual day upon the illumined half, perpetual night upon
the other hemisphere, and a fairly large zone of twilight between the
two. Such a condition would indeed be different from the succession of
terrestrial days and nights.
As seen from Mercury, the Earth we inhabit would shine out in the starry
sky[9] as a magnificent orb of first magnitude, with the Moon
alongside, a faithful little companion. They should form a fine double
star, the Earth being a brilliant orb of first magnitude, and the Moon
of third, a charming couple, and admired doubtless as an enchanted and
privileged abode.
It is at midnight during the oppositions of the Earth with the Sun that
our planet is the most beautiful and brilliant, as is Jupiter for
ourselves. The constellations are the same, viewed from Mercury or from
the Earth.
But is this little solar planet inhabited? We do not yet know. We can
only reply: why not?
VENUS
When the sunset atmosphere is crimson with the glorious rays of the King
of Orbs, and all Nature assumes the brooding veil of twilight, the most
indifferent eyes are often attracted and captivated by the presence of a
star that is almost dazzling, and illuminates with its white and limpid
light the heavens darkened by the disappearance of the God of Day.
Hail, Venus, Queen of the Heavens! the "Shepherd's Star," gentle mother
of the loves, goddess of beauty, eternally adored and cherished, sung
and immortalized upon Earth, by poets and artists. Her splendid
brilliancy attracted notice from earliest antiquity, and we find her,
radiant and charming, in the works of the ancients, who erected altars
to her and adorned their poetry with her grace and beauty. Homer calls
her Callisto the Beautiful; Cicero names her Vesper, the evening star,
and Lucifer, the star of the morning--for it was with this divinity as
with Mercury. For a long while she was regarded as two separate planets,
and it was only when it came to be observed that the evening and the
morning star were always in periodic succession, that the identity of
the orb was recognized.
Her radiant splendor created her mythological personality, just as the
agility of Mercury created that of the messenger of the gods.
We do not see her aerial chariot in the Heavens drawn by a flight of
doves with white and fluttering wings, but we follow the lustrous orb
led on through space by solar attraction. And in the beautiful evenings
when she is at her greatest distance from our Sun, the whole world
admires this white and dazzling Venus reigning as sovereign over our
twilight[10] for hours after sunset, and in addition to the _savants_
who are practically occupied with astronomy, millions of eyes are raised
to this celestial splendor, and for a moment millions of human beings
feel some curiosity about the mysteries of the Infinite. The brutalities
of daily life would fain petrify our dreams, but thought is not yet
stifled to the point of checking all aspirations after eternal truth,
and when we gaze at the starry sky it is hard not to ask ourselves the
nature of those other worlds, and the place occupied by our own planet
in the vast concert of sidereal harmony.
[Illustration: FIG. 36.--The Evening Star.]
Even through a small telescope, Venus offers remarkable phases.
[Illustration: FIG. 37.--Successive phases of Venus.]
Fig. 37 gives some notion of the succession of these, and of the
planet's variations in magnitude during its journey round the Sun.
Imagine it to be rotating in a year of 224 days, 16 hours, 49 minutes, 8
seconds at a distance of 108 million kilometers (67,000,000 miles), the
Earth being at 149 million kilometers (93,000,000 miles). Like Mercury,
at certain periods it passes between the Sun and ourselves, and as its
illuminated hemisphere is of course turned toward the orb of day, we at
those times perceive only a sharp and very luminous crescent. At such
periods Venus is entirely, so to say, against the Sun, and presents to
us her greatest apparent dimension (Fig. 38). Sometimes, again, like
Mercury, she passes immediately in front of the Sun, forming a perfectly
round black spot; this happened on December 8, 1874, and December 6,
1882; and will recur on June 7, 2004, and June 5, 2012. These transits
have been utilized in celestial geometry in measuring the distance of
the Sun.
You will readily divine that the distance of Venus varies considerably
according to her position in relation to the Earth: when she is between
the Sun and ourselves she is nearest to our world; but it is just at
those times that we see least of her surface, because she exhibits to us
only a slender crescent. Terrestrial astronomers are accordingly very
badly placed for the study of her physical constitution. The best
observations can be made when she is situated to right or left of the
Sun, and shows us about half her illuminated disk--during the day for
choice, because at night there is too much irradiation from her dazzling
light.
These phases were discovered by Galileo, in 1610. His observations were
among the first that confirmed the veracity of the system of Copernicus,
affording an evident example of the movement of the planets round the
sun. They are often visible to the unaided eye with good sight, either
at dusk, or through light clouds.
[Illustration: FIG. 38.--Venus at greatest brilliancy.]
Venus, surrounded by a highly dense and rarefied atmosphere, which
increases the difficulties of observing her surface, might be called the
twin sister of the Earth, so similar are the dimensions of the two
worlds. But, strange as it may seem to the many admirers, who are ready
to hail in her an abode of joy and happiness, it is most probable that
this planet, attractive as she is at a distance, would be a less
desirable habitation than our floating island. In fact, the atmosphere
of Venus is perpetually covered with cloud, so that the weather there
must be always foggy. No definite geographical configuration can be
discovered on her, despite the hopes of the eighteenth-century
astronomers. We are not even sure that she rotates upon herself, so
contradictory are the observations, and so hard is it to distinguish
anything clearly upon her surface. A single night of observation
suffices to show the rotation of Mars or of Jupiter; but the beautiful
Evening Star remains obstinately veiled from our curiosity.
Several astronomers, and not the least considerable, think that the
tides produced by the Sun upon her seas, or globe in its state of
pristine fluidity, must have been strong enough to seize and fix her, as
the Earth did for the Moon, thus obliging her to present always the same
face to the Sun. Certain telescopic observations would even seem to
confirm this theoretical deduction from the calculations of celestial
mechanics.
The author ventures to disagree with this opinion, its apparent
probability notwithstanding, because he has invariably received a
contrary impression from all his telescopic observations. He has quite
recently (spring of 1903) repeated these observations. Choosing a
remarkably clear and perfectly calm atmosphere, he examined the splendid
planet several times with great attention in the field of the telescope.
The right or eastern border (reversed image) was dulled by the
atmosphere of Venus; this is the line of separation between day and
night. Beneath, at the extreme northern edge, he was attracted on each
occasion by a small white patch, a little whiter than the rest of the
surface of the planet, surrounded by a light-gray penumbra, giving the
exact effect of a polar snow, very analogous to that observed at the
poles of Mars. To the author this white spot on the boreal horn of
Venus does not appear to be due to an effect of contrast, as has
sometimes been supposed.
Now, if the globe of Venus has poles, it must turn upon itself.
Unfortunately it has proved impossible to distinguish any sign upon the
disk, indicative of the direction and speed of its rotary movement,
although these observations were made, with others, under excellent
conditions.--Three o'clock in the afternoon, brilliant sun, sky clear
blue, the planet but little removed from the meridian--at which time it
is less dazzling than in the evening.
There is merely the impression; but it is so definite as to prevent the
author from adopting the new hypothesis, in virtue of which the planet,
as it gravitates round the Sun, presents always the same hemisphere.
If this hypothesis were a reality, Venus would certainly be a very
peculiar world. Eternal day on the one side; eternal night on the other.
Maximum light and heat at the center of the hemisphere perpetually
turned to the Sun; maximum cold and center of night at the antipodes.
This icy hemisphere would possibly be uninhabitable, but the resources
of Nature are so prodigious, and the law of Life is so imperious, so
persistent, under the most disadvantageous and deplorable terrestrial
conditions, that it would be transcending our rights to declare an
impossibility of existence, even in this eternal night. The currents of
the atmosphere would no doubt suffice to set up perpetual changes of
temperature between the two hemispheres, in comparison with which our
trade-winds would be the lightest of breezes.
Yes, mystery still reigns upon this adjacent earth, and the most
powerful instruments of the observatories of the whole world have been
unable to solve it. All we know is that the diameter, surface, volume
and mass of this planet, and its weight at the surface, do not differ
sensibly from those that characterize our own globe: that this planet is
sister to our own, and of the same order, hence probably formed of the
same elements. We further know that, as seen from Venus (Fig. 39), the
Earth on which we live is a magnificent star, a double orb more
brilliant even than when viewed from Mercury. It is a dazzling orb of
first magnitude, accompanied by its moon, a star of the second and a
half magnitude.
And thus the worlds float on in space, distant symbols of hopes not
realized on any one of them, all at different stages of their degree of
evolution, representing an ever-growing progress in the sequence of the
ages.
[Illustration: FIG. 39.--The Earth viewed from Venus.]
When we contemplate this radiant Venus, it is difficult, even if we can
not form any definite idea as to her actual state as regards habitation,
to assume that she must be a dreary desert, and not, on the contrary,
to hail in her a celestial land, differing more or less from our own
dwelling-place, travailing with her sisters in the accomplishment of the
general plan of Nature.
Such are the characteristic features of our celestial neighbor. In
quitting her, we reach the Earth, which comes immediately next her in
order of distance, 149 million kilometers (93,000,000 miles) from the
Sun, but as we shall devote an entire chapter to our own planet, we will
not halt at this point, but cross in one step the distance that
separates Mars from Venus.
Let us only remark in passing, that our planet is the largest of the
four spheres adjacent to the Sun. Here are their comparative diameters:
The Earth = 1. In Kilometers. In Miles.
Mercury 0.373 4,750 2,946
Venus 0.999 12,730 7,894
Earth 1.000 12,742 7,926
Mars 0.528 6,728 4,172
It will be seen that Venus is almost identical with the Earth.
MARS
Two hundred and twenty-six millions of kilometers (140,000,000 miles)
from the Sun is the planet Mars, gravitating in an orbit exterior to
that which the Earth takes annually round the same center.
Unfortunate Mars! What evil fairy presided at his birth? From
antiquity, all curses seem to have fallen upon him. He is the god of war
and of carnage, the protector of armies, the inspirer of hatred among
the peoples, it is he who pours out the blood of Humanity in
international hecatombs. Here, again, as in the case of Mercury and
Venus, the appearance has originated the idea. Mars, in fact, burns like
a drop of blood in the depths of the firmament, and it is this ruddy
color that inspired its name and attributes, just as the dazzling
whiteness of Venus made her the goddess of love and beauty. Why, indeed,
should the origins of mythology be sought elsewhere than in astronomy?
While Humanity was attributing to the presumptive influence of Mars the
defects inherent in its own terrestrial nature, this world, unwitting of
our sorrows, pursued the celestial path marked out for it in space by
destiny.
This planet is, as we have said, the first encountered after the Earth.
Its orbit is very elongated, very eccentric. Mars accomplishes it in a
period of 1 year, 321 days, 22 hours, _i.e._, 1 year, 10 months, 21
days, or 687 days. The velocity of its transit is 23 kilometers (14.5
miles) per second; that of the Earth is 30 (19 miles). Our planet,
traveling through space at an average distance of 149 million kilometers
(93,000,000 miles) from the central focus, is separated from Mars by an
average distance of 76 million kilometers (47,000,000 miles); but as its
orbit is equally elliptic and elongated it follows that at certain
epochs the two planets approach one another by something less than 60
million kilometers (37,000,000 miles). These are the periods selected
for making the best observations upon our neighbor of the ruddy rays.
The oppositions of Mars arrive about every twenty-six months, but the
periods of its greatest proximity, when this planet approaches to within
56 million kilometers (34,700,000 miles) of the Earth, occur only every
fifteen years.
Mars is then passing perihelion, while our world is at aphelion (or
greatest distance from the Sun). At such epochs this globe presents to
us an apparent diameter 63 times smaller than that of the Moon, _i.e._,
a telescope that magnifies 63 times would show him to us of the same
magnitude as our satellite viewed with the unaided eye, and an
instrument that magnified 630 times would show him ten times larger in
diameter.
In dimensions he differs considerably from our world, being almost half
the size of the Earth. In diameter he measures only 6,728 kilometers
(4,172 miles), and his circumference is 21,125 kilometers (13,000
miles). His surface is only 29/100 of the terrestrial surface, and his
volume only 15/100 of our own.
This difference in volume causes Mars to be an earth in miniature. When
we study his aspects, his geography, his meteorology, we seem to see in
space a reduction of our own abode, with certain dissimilarities that
excite our curiosity, and make him even more interesting to us.
The Martian world weighs nine times and a half less than our own. If we
represent the weight of the Earth by 1,000, that of Mars would be
represented by 105. His density is much less than our own; it is only
7/10 that of the Earth. A man weighing 70 kilograms, transported to the
adjacent globe, would weigh only 26 kilograms.
The earliest telescopic observations revealed the existence of more or
less accentuated markings upon the surface of Mars. The progress of
optics, admitting of greater magnifications, exhibited the form of these
patches more clearly, while the study of their motions enabled the
astronomers to determine with remarkable precision the diurnal rotation
of this planet. It occurs in 24 hours, 37 minutes, 23.65 seconds. Day
and night are accordingly a little longer on Mars than on the Earth, but
the difference is obviously inconsiderable. The year of Mars consists of
668 Martian days. The inclination of the axis of rotation of this globe
upon the plane of its orbit is much the same as our own. In
consequence, its seasons are analogous to ours in intensity, while twice
the length, the Martian year being almost equal to two of our years. The
intensity of the seasons is indeed more accentuated than upon the Earth,
since the orbit of Mars is very elongated. But there, as here, are three
quite distinct zones: the torrid, the temperate, and the glacial.
By means of the telescope we can follow the variations of the Martian
seasons, especially in what concerns the polar snows, which regularly
aggregate during the winter, and melt no less regularly during the heat
of the summer. These snows are very easily observed, and stand out
clearly with dazzling whiteness. The reader can judge of them by the
accompanying figure, which sums up the author's observations during one
of the recent oppositions of Mars (1900-1901). The size of the polar cap
diminished from 4,680 kilometers to 840. The solstice of the Martian
summer was on April 11th. The snows were still melting on July 6th.
Sometimes they disappear almost entirely during the Martian month that
corresponds to our month of August, as never happens with our polar ice.
Hence, though this planet is farther away from the Sun than ourselves,
it does not appear to be colder, or, at any rate, it is certain that the
polar snows are much less thick.
On the other hand, there are hardly ever clouds on Mars; the Martian
atmosphere is almost always limpid, and one can say that fine weather is
the chronic state of the planet. At times, light fogs or a little vapor
will appear in certain regions, but they are soon dissipated, and the
sky clears up again.
[Illustration: FIG. 40.--Diminution of the polar snows of Mars during
the summer.]
Since the invention of the telescope, a considerable number of drawings
have been made, depicting Mars under every aspect, and the agreement
between these numerous observations gives us a sufficient acquaintance
with the planet to admit of our indicating the characteristic features
of its geography, and of drawing out _areographic_ maps (_Ares_, Mars).
Its appearance can be judged of from the two drawings here reproduced,
as made (February, 1901) at the Observatory of Juvisy, and from the
general chart drawn from the total sum of observations (Figs. 41, 42 and
43).
It will be seen at the first glance that the geography of Mars is very
different from that of our own globe: while three-quarters of the Earth
are covered with the liquid element, Mars seems to be more evenly
divided, and must indeed have rather more land than water. We find no
immense oceans surrounding the continents, and separating them like
islands; on the contrary, the seas are reduced to long gulfs compressed
between the shores, like the Mediterranean for example, nor is it even
certain that these gray spots do all represent true seas. It has been
agreed to term _sea_ the parts that are lightly tinged with green, and
to give the name of _continent_ to the spots colored yellow. That is the
hue of the Martian soil, due either to the soil itself, which would
resemble that of the Sahara, or, to take a less arid region, that seen
on the line between Marseilles and Nice, in the vicinity of the
Esterels; or perhaps to some peculiar vegetation. During ascents in a
balloon, the author has often remarked that the hue of the ripe corn,
with the Sun shining on it, is precisely that presented to us by the
continents of Mars in the best hours for observation.
[Illustration: FIG. 41.--Telescopic aspect of the planet Mars (Feb.,
1901).]
As to the "seas," it is pretty certain that there must be water, or
some kind of liquid, deriving above all from the melting of the polar
snows in spring and summer; but it may possibly be in conjunction with
some vegetation, aquatic plants, or perhaps vast meadows, which appear
to us from here to be the more considerable in proportion as the water
that nourishes them has been more abundant.
[Illustration: FIG. 42.--Telescopic aspect of the planet Mars (Feb.,
1901).]
Mars, like our globe, is surrounded with a protective atmosphere, which
retains the rays of the Sun, and must preserve a medium temperature
favorable to the conservation of life upon the surface of the planet.
But the circulation of the water, so important to terrestrial life,
whether animal or vegetable, which is effected upon our planet by the
evaporation of the seas, clouds, winds, rains, wells, rivers and
streams, comes about quite differently on Mars; for, as was remarked
above, it is rarely that any clouds are observed there. Instead of being
vertical, as here, this circulation is horizontal: the water coming from
the source of the polar snows finds its way into the canals and seas,
and returns to be condensed at the poles by a light drift of invisible
vapors directed from the equator to the poles. There is never any rain.
We have spoken of _canals_. One of the great puzzles of the Martian
world is incontestably the appearance of straight lines that furrow its
surface in all directions, and seem to connect the seas. M.
Schiaparelli, the distinguished Director of the Observatory of Milan,
who discovered them in 1877, called them canals, without, however,
postulating anything as to their real nature. Are they indeed canals?
These straight lines, measuring sometimes 600 kilometers (372 miles) in
length, and more than 100 kilometers (62 miles) in breadth, have much
the same hue as the seas on which they open. For a quarter of a century
they have been surveyed by the greater number of our observers. But it
must be confessed that, even with the best instruments, we only approach
Mars at a distance of 60,000 kilometers (37,200 miles), which is still a
little far off, and we may be sure that we do not distinguish the true
details of the surface.[11] These details at the limits of visibility
produce the appearance of canals to our eyes. They may possibly be lines
of lakes, or oases. The future will no doubt clear up this mystery for
us.
[Illustration: FIG. 43.--Chart of Mars.]
As to the inhabitants of Mars, this world is in a situation as
favorable as our Earth for habitation, and it would be difficult to
discover any reason for perpetual sterility there. It appears to us, on
the contrary, by its rapid and frequent variations of aspect, to be a
very living world. Its atmosphere, which is always clear, has not the
density of our own, and resembles that of the highest mountains. The
conditions of existence there vary from ours, and appear to be more
delicate, more ethereal.
There as here, day succeeds to night, spring softens the rigors of
winter; the seasons unfold, less disparate than our own, of which we
have such frequent reason to complain. The sky is perpetually clear.
There are never tempests, hurricanes, nor cyclones, the wind never gets
up any force there, on account of the rarity of the atmosphere, and the
low intensity of weight.
Differing from ours, this world may well be a more congenial
habitation. It is more ancient than the Earth, smaller, less massive. It
has run more quickly through the phases of its evolution. Its astral
life is more advanced, and its Humanity should be superior to our own,
just as our successors a million years hence, for example, will be less
coarse and barbarous than we are at present: the law of progress governs
all the worlds, and, moreover, the physical constitution of the planet
Mars is less dense than our own.
There is no need to despair of entering some day into communication with
these unknown beings. The luminous points that have been observed are no
signals, but high summits or light clouds illuminated by the rising or
setting sun. But the idea of communication with them in the future is no
more audacious and no less scientific than the invention of spectral
analysis, X-rays, or wireless telegraphy.
We may suppose that the study of astronomy is further advanced in Mars
than on the Earth, because humanity itself has advanced further, and
because the starry sky is far finer there, far easier to study, owing to
the limpidity of its pure, clear atmosphere.
Two small moons (hardly larger than the city of Paris) revolve rapidly
round Mars; they are called Phobos and Deimos. The former, at a distance
of 6,000 kilometers (3,730 miles) from the surface, accomplishes its
revolution rapidly, in seven hours, thirty-nine minutes, and thus makes
the entire circle of the Heavens three times a day. The second
gravitates at 20,000 kilometers (12,400 miles), and turns round its
center of attraction in thirty hours and eighteen minutes. These two
satellites were discovered by Mr. Hall, at the University of Washington,
in the month of August, 1877.
* * * * *
Among the finest and most interesting of the celestial phenomena admired
by the Martians, at certain epochs of the year,--now at night when the
Sun has plunged into his fiery bed, now in the morning, a little before
the aurora,--is a magnificent star of first magnitude, never far removed
from the orb of day, which presents to them the same aspects as does
Venus to ourselves. This splendid orb, which has doubtless received the
most flattering names from those who contemplate it, this radiant star
of a beautiful greenish blue, courses in space accompanied by a little
satellite, sparkling like some splendid diamond, after sunset, in the
clear sky of Mars. This superb orb is the Earth, and the little star
accompanying it is the Moon.
[Illustration: FIG. 44.--The Earth viewed from Mars.]
Yes, to the Martians our Earth is a star of the morning and evening;
doubtless they have determined her phases. Many a vow, and many a hope
must have been wafted toward her, more than one broken heart must have
permitted its unrealized dreams to wander forth to our planet as to an
abode of happiness where all who have suffered in their native world
might find a haven. But our planet, alas! is not as perfect as they
imagine.
We must not dally upon Mars, but hasten our celestial excursion toward
Jupiter.