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OTHER WORLDS
by
GARRETT P. SERVISS.
* * * * * *
OTHER WORLDS.
Their Nature and Possibilities in the Light of the Latest
Discoveries. Illustrated. 12mo. Cloth, $1.20 net; postage
additional.
No science has ever equaled astronomy in its appeal to the
imagination, and recently popular interest in the wonders of the
starry heavens has been stimulated by surprising discoveries and
imaginary discoveries, as well as by a marked tendency of writers
of fiction to include other worlds and their possible inhabitants
within the field of romance.
Mr. Serviss's new book on "Other Worlds, their Nature and
Possibilities in the Light of the Latest Discoveries," summarizes
what is known. With helpful illustrations, the most interesting
facts about the planets Venus, Mars, Jupiter, Saturn, etc., as well
as about the nearest of all other worlds, the moon, are presented
in a popular manner, and always from the point of view of human
interest--a point that is too seldom taken by writers on science.
ASTRONOMY WITH AN OPERA-GLASS.
A Popular Introduction to the Study of the Starry Heavens with the
simplest of Optical Instruments. Illustrated. 8vo. Cloth, $1.50.
"By its aid thousands of people who have resigned themselves to the
ignorance in which they were left at school, by our wretched system
of teaching by the book only, will thank Mr. Serviss for the
suggestions he has so well carried out."--_New York Times._
PLEASURES OF THE TELESCOPE.
A Descriptive Guide to Amateur Astronomers and All Lovers of the
Stars. Illustrated. 8vo. Cloth, $1.50.
"The volume will be found interesting by those for whom it is
written, and will inspire many with a love for the study of
astronomy, one of the most far-reaching of the
sciences."--_Milwaukee Journal._
D. APPLETON AND COMPANY, NEW YORK.
* * * * * *
[Illustration: CHART OF MARS. After Schiaparelli.]
OTHER WORLDS
Their Nature, Possibilities and Habitability in the Light of the Latest
Discoveries.
by
GARRETT P. SERVISS
Author of
"Astronomy with an Opera-glass" and "Pleasures of the Telescope"
With Charts and Illustrations
"Shall we measure the councils of heaven by the narrow impotence of
human faculties, or conceive that silence and solitude reign
throughout the mighty empire of nature?"
--DR. THOMAS CHALMERS.
New York
D. Appleton and Company
1901
Copyright, 1901,
by D. Appleton and Company.
TO THE MEMORY OF WILLIAM JAY YOUMANS.
PREFACE
The point of view of this book is human interest in the other worlds
around us. It presents the latest discoveries among the planets of the
solar system, and shows their bearing upon the question of life in those
planets. It points out the resemblances and the differences between the
earth and the other worlds that share with it in the light of the sun.
It shows what we should see and experience if we could visit those
worlds.
While basing itself upon facts, it does not exclude the discussion of
interesting probabilities and theories that have commanded wide popular
attention. It points out, for instance, what is to be thought of the
idea of interplanetary communication. It indicates what must be the
outlook of the possible inhabitants of some of the other planets toward
the earth. As far as may be, it traces the origin and development of the
other worlds of our system, and presents a graphic picture of their
present condition as individuals, and of their wonderful contrasts as
members of a common family.
In short, the aim of the author has been to show how wide, and how rich,
is the field of interest opened to the human mind by man's discoveries
concerning worlds, which, though inaccessible to him in a physical
sense, offer intellectual conquests of the noblest description.
And, finally, in order to assist those who may wish to recognize for
themselves these other worlds in the sky, this book presents a special
series of charts to illustrate a method of finding the planets which
requires no observatory and no instruments, and only such knowledge of
the starry heavens as anybody can easily acquire.
G.P.S.
BOROUGH OF BROOKLYN, NEW YORK CITY,
_September, 1901._
CONTENTS
CHAPTER I
_INTRODUCTORY_ 1
Remarkable popular interest in questions concerning
other worlds and their inhabitants--Theories of
interplanetary communication--The plurality of worlds in
literature--Romances of foreign planets--Scientific interest
in the subject--Opposing views based on telescopic and
spectroscopic revelations--Changes of opinion--Desirability
of a popular presentation of the latest facts--The natural
tendency to regard other planets as habitable--Some of the
conditions and limitations of the problem--The solar system
viewed from outer space--The resemblances and contrasts of
its various planets--Three planetary groups recognized--The
family character of the solar system
CHAPTER II
_MERCURY, A WORLD OF TWO FACES AND MANY CONTRASTS_ 18
Grotesqueness of Mercury considered as a world--Its
dimensions, mass, and movements--The question of an
atmosphere--Mercury's visibility from the earth--Its
eccentric orbit, and rapid changes of distance from the
sun--Momentous consequences of these peculiarities--A
virtual fall of fourteen million miles toward the sun
in six weeks--The tremendous heat poured upon Mercury
and its great variations--The little planet's singular
manner of rotation on its axis--Schiaparelli's astonishing
discovery--A day side and a night side--Interesting effects
of libration--The heavens as viewed from Mercury--Can it
support life?
CHAPTER III
_VENUS, THE TWIN OF THE EARTH_ 46
A planet that matches ours in size--Its beauty in the
sky--Remarkable circularity of its orbit--Probable
absence of seasons and stable conditions of temperature
and weather on Venus--Its dense and abundant atmosphere--Seeing
the atmosphere of Venus from the earth--Is the real face of the
planet hidden under an atmospheric veil?--Conditions of
habitability--All planetary life need not be of the terrestrial
type--The limit fixed by destructive temperature--Importance of
air and water in the problem--Reasons why Venus may be a
more agreeable abode than the earth--Splendor of our globe
as seen from Venus--What astronomers on Venus might learn
about the earth--A serious question raised--Does Venus, like
Mercury, rotate but once in the course of a revolution about
the sun?--Reasons for and against that view
CHAPTER IV
_MARS, A WORLD MORE ADVANCED THAN OURS_ 85
Resemblances between Mars and the earth--Its seasons and its
white polar caps--Peculiar surface markings--Schiaparelli's
discovery of the canals--His description of their appearance
and of their duplication--Influence of the seasons on the
aspect of the canals--What are the canals?--Mr. Lowell's
observations--The theory of irrigation--How the inhabitants
of Mars are supposed to have taken advantage of the annual
accession of water supplied by the melting of the polar
caps--Wonderful details shown in charts of Mars--Curious
effects that may follow from the small force of gravity
on Mars--Imaginary giants--Reasons for thinking that
Mars may be, in an evolutionary sense, older than the
earth--Speculations about interplanetary signals from
Mars, and their origin--Mars's atmosphere--The question of
water--The problem of temperature--Eccentricities of Mars's
moons
CHAPTER V
_THE ASTEROIDS, A FAMILY OF DWARF WORLDS_ 129
Only four asteroids large enough to be measured--Remarkable
differences in their brightness irrespective of size--Their
widely scattered and intermixed orbits--Eccentric orbit of
Eros--the nearest celestial body to the earth except the
moon--Its existence recorded by photography before it was
discovered--Its great and rapid fluctuations in light, and
the curious hypotheses based upon them--Is it a fragment of
an exploded planet?--The startling theory of Olbers as to
the origin of the asteroids revived--Curious results of the
slight force of gravity on an asteroid--An imaginary visit
to a world only twelve miles in diameter
CHAPTER VI
_JUPITER, THE GREATEST OF KNOWN WORLDS_ 160
Jupiter compared with our globe--His swift rotation on his
axis--Remarkable lack of density--The force of gravity on
Jupiter--Wonderful clouds--Strange phenomena of the great
belts--Brilliant display of colors--The great red spot
and the many theories it has given rise to--Curious facts
about the varying rates of rotation of the huge planet's
surface--The theory of a hidden world in Jupiter--When
Jupiter was a companion star to the sun--The miracle of
world-making before our eyes--Are Jupiter's satellites
habitable?--Magnificent spectacles in the Jovian system
CHAPTER VII
_SATURN, A PRODIGY AMONG PLANETS_ 185
The wonder of the great rings--Saturn's great distance and
long year--The least dense of all the planets--It would
float in water--What kind of a world is it?--Sir Humphry
Davy's imaginary inhabitants of Saturn--Facts about the
rings, which are a phenomenon unparalleled in the visible
universe--The surprising nature of the rings, as revealed
by mathematics and the spectroscope--The question of their
origin and ultimate fate--Dr. Dick's idea of their
habitability--Swedenborg's curious description of the
appearance of the rings from Saturn--Is Saturn a globe of
vapor, or of dust?--The nine satellites and "Roche's
limit"--The play of spectacular shadows in the Saturnian
system--Uranus and Neptune--Is there a yet undiscovered
planet greater than Jupiter?
CHAPTER VIII
_THE MOON, CHILD OF THE EARTH AND THE SUN_ 212
The moon a favorite subject for intellectual speculation--Its
nearness to the earth graphically illustrated--Ideas of the
ancients--Galileo's discoveries--What first raised a serious
question as to its habitability--Singularity of the moon's
motions--Appearance of its surface to the naked eye and with
the telescope--The "seas" and the wonderful mountains and
craters--A terrible abyss described--Tycho's mysterious
rays--Difference between lunar and terrestrial
volcanoes--Mountain-ringed valleys--Gigantic cracks in the
lunar globe--Slight force of gravity of the moon and some
interesting deductions--The moon a world of giantism--What
kind of atmospheric gases can the moon contain--The question
of water and of former oceans--The great volcanic cataclysm
in the moon's history--Evidence of volcanic and other
changes now occurring--Is there vegetation on the
moon?--Lunar day and night--The earth as seen from the
moon--Discoveries yet to be made
CHAPTER IX
_HOW TO FIND THE PLANETS_ 256
It is easy to make acquaintance with the planets and to
follow them among the stars--The first step a knowledge of
the constellations--How this is to be acquired--How to use
the Nautical Almanac in connection with the charts in this
book--The visibility of Mercury and Venus--The oppositions
of Mars, Jupiter, and Saturn
INDEX 277
LIST OF ILLUSTRATIONS
PAGE
Chart of Mars _Frontispiece_
Diagram showing causes of day and night on portions of Mercury 35
Regions of day and night on Mercury 38
Venus's atmosphere seen as a ring of light 56
View of Jupiter _facing_ 168
Three views of Saturn _facing_ 186
Diagram showing the moon's path through space 217
The lunar Alps, Apennines, and Caucasus _facing_ 222
The moon at first and last quarter _facing_ 226
Phases and rotation of the moon 250
Charts showing the zodiacal constellations:
1. From right ascension 0 hours to 4 hours 259
2. " " 4 " " 8 " 261
3. " " 8 " " 2 " 263
4. " " 12 " " 16 " 265
5. " " 16 " " 20 " 267
6. " " 20 " " 24 " 269
OTHER WORLDS
CHAPTER I
INTRODUCTORY
Other worlds and their inhabitants are remarkably popular subjects of
speculation at the present time. Every day we hear people asking one
another if it is true that we shall soon be able to communicate with
some of the far-off globes, such as Mars, that circle in company with
our earth about the sun. One of the masters of practical electrical
science in our time has suggested that the principle of wireless
telegraphy may be extended to the transmission of messages across space
from planet to planet. The existence of intelligent inhabitants in some
of the other planets has become, with many, a matter of conviction, and
for everybody it presents a question of fascinating interest, which has
deeply stirred the popular imagination.
The importance of this subject as an intellectual phenomenon of the
opening century is clearly indicated by the extent to which it has
entered into recent literature. Poets feel its inspiration, and
novelists and romancers freely select other planets as the scenes of
their stories. One tells us of a visit paid by men to the moon, and of
the wonderful things seen, and adventures had, there. Lucian, it is
true, did the same thing eighteen hundred years ago, but he had not the
aid of hints from modern science to guide his speculations and lend
verisimilitude to his narrative.
Another startles us from our sense of planetary security with a
realistic account of the invasion of the earth by the terrible sons of
warlike Mars, seeking to extend their empire by the conquest of foreign
globes.
Sometimes it is a trip from world to world, a kind of celestial pleasure
yachting, with depictions of creatures more wonderful than--
"The anthropophagi and men whose heads
Do grow beneath their shoulders"--
that is presented to our imagination; and sometimes we are informed of
the visions beheld by the temporarily disembodied spirits of trance
mediums, or other modern thaumaturgists, flitting about among the
planets.
Then, to vary the theme, we find charming inhabitants of other worlds
represented as coming down to the earth and sojourning for a time on our
dull planet, to the delight of susceptible successors of father Adam,
who become, henceforth, ready to follow their captivating visitors to
the ends of the universe.
In short, writers of fiction have already established interplanetary
communication to their entire satisfaction, thus vastly and indefinitely
enlarging the bounds of romance, and making us so familiar with the
peculiarities of our remarkable brothers and sisters of Mars, Venus,
and the moon, that we can not help feeling, notwithstanding the many
divergences in the descriptions, that we should certainly recognize them
on sight wherever we might meet them.
But the subject is by no means abandoned to the tellers of tales and the
dreamers of dreams. Men of science, also, eagerly enter into the
discussion of the possibilities of other worlds, and become warm over
it.
Around Mars, in particular, a lively war of opinions rages. Not all
astronomers have joined in the dispute--some have not imagination
enough, and some are waiting for more light before choosing sides--but
those who have entered the arena are divided between two opposed camps.
One side holds that Mars is not only a world capable of having
inhabitants, but that it actually has them, and that they have given
visual proof of their existence and their intelligence through the
changes they have produced upon its surface. The other side maintains
that Mars is neither inhabited nor habitable, and that what are taken
for vast public works and engineering marvels wrought by its
industrious inhabitants, are nothing but illusions of the telescope, or
delusions of the observer's mind. Both adduce numerous observations,
telescopic and spectroscopic, and many arguments, scientific and
theoretic, to support their respective contentions, but neither side has
yet been able to convince or silence the other, although both have made
themselves and their views intensely interesting to the world at large,
which would very much like to know what the truth really is.
And not only Mars, but Venus--the beauteous twin sister of the earth,
who, when she glows in the evening sky, makes everybody a lover of the
stars--and even Mercury, the Moor among the planets, wearing "the
shadowed livery of the burnished sun," to whom he is "a neighbor and
near bred," and Jupiter, Saturn, and the moon itself--all these have
their advocates, who refuse to believe that they are lifeless globes,
mere reflectors of useless sunshine.
The case of the moon is, in this respect, especially interesting, on
account of the change that has occurred in the opinions held concerning
its physical condition. For a very long time our satellite was
confidently, and almost universally, regarded as an airless, waterless,
lifeless desert, a completely "dead world," a bare, desiccated skull of
rock, circling about the living earth.
But within a few years there has been a reaction from this extreme view
of the lifelessness of the moon. Observers tell us of clouds suddenly
appearing and then melting to invisibility over volcanic craters; of
evidences of an atmosphere, rare as compared with ours, yet manifest in
its effects; of variations of color witnessed in certain places as the
sunlight drifts over them at changing angles of incidence; of what seem
to be immense fields of vegetation covering level ground, and of
appearances indicating the existence of clouds of ice crystals and
deposits of snow among the mountainous lunar landscapes. Thus, in a
manner, the moon is rehabilitated, and we are invited to regard its
silvery beams not as the reflections of the surface of a desert, but as
sent back to our eyes from the face of a world that yet has some slight
remnants of life to brighten it.
The suggestion that there is an atmosphere lying close upon the shell of
the lunar globe, filling the deep cavities that pit its face and
penetrating to an unknown depth in its interior, recalls a speculation
of the ingenious and entertaining Fontenelle, in the seventeenth
century--recently revived and enlarged upon by the author of one of our
modern romances of adventure in the moon--to the effect that the lunar
inhabitants dwell beneath the surface of their globe instead of on the
top of it.
Now, because of this widespread and continually increasing interest in
the subject of other worlds, and on account of the many curious
revelations that we owe to modern telescopes and other improved means of
investigation, it is certainly to be desired that the most important and
interesting discoveries that have lately been made concerning the
various globes which together with the earth constitute the sun's
family, should be assembled in a convenient and popular form--and that
is the object of this book. Fact is admittedly often stranger and more
wonderful than fiction, and there are no facts that appeal more
powerfully to the imagination than do those of astronomy. Technical
books on astronomy usually either ignore the subject of the habitability
of the planets, or dismiss it with scarcely any recognition of the
overpowering human interest that it possesses. Hence, a book written
specially from the point of view of that subject would appear calculated
to meet a popular want; and this the more, because, since Mr. Proctor
wrote his Other Worlds than Ours and M. Flammarion his Pluralité des
Mondes Habités, many most important and significant discoveries have
been made that, in several notable instances, have completely altered
the aspect in which the planets present themselves for our judgment as
to their conditions of habitability.
No doubt the natural tendency of the mind is to regard all the planets
as habitable worlds, for there seems to be deeply implanted in human
nature a consciousness of the universality of life, giving rise to a
conviction that one world, even in the material sense, is not enough for
it, but that every planet must belong to its kingdom. We are apt to say
to ourselves: "The earth is one of a number of planets, all similarly
circumstanced; the earth is inhabited, why should not the others also be
inhabited?"
What has been learned of the unity in chemical constitution and
mechanical operation prevailing throughout the solar system, together
with the continually accumulating evidence of the common origin of its
various members, and the identity of the evolutionary processes that
have brought them into being, all tends to strengthen the _a priori_
hypothesis that life is a phenomenon general to the entire system, and
only absent where its essential and fundamental conditions, for special
and local, and perhaps temporary, reasons, do not exist.
If we look for life in the sun, for instance, while accepting the
prevalent conception of the sun as a center of intense thermal action,
we must abandon all our ideas of the physical organization of life
formed upon what we know of it from experimental evidence. We can not
imagine any form of life that has ever been presented to our senses as
existing in the sun.
But this is not generally true of the planets. Life, in our sense of it,
is a planetary, not a solar, phenomenon, and while we may find reasons
for believing that on some of the planets the conditions are such that
creatures organized like ourselves could not survive, yet we can not
positively say that every form of living organism must necessarily be
excluded from a world whose environment would be unsuited for us and our
contemporaries in terrestrial life.
Although our sole knowledge of animated nature is confined to what we
learn by experience on the earth, yet it is a most entertaining, and by
no means unedifying, occupation, to seek to apply to the exceedingly
diversified conditions prevailing in the other planets, as astronomical
observations reveal them to us, the principles, types, and limitations
that govern the living creatures of our world, and to judge, as best we
can, how far those types and limits may be modified or extended so that
those other planets may reasonably be included among the probable abodes
of life.
In order to form such judgments each planet must be examined by itself,
but first it is desirable to glance at the planetary system as a whole.
To do this we may throw off, in imagination, the dominance of the sun,
and suppose ourselves to be in the midst of open space, far removed both
from the sun and the other stars. In this situation it is only by
chance, or through foreknowledge, that we can distinguish our sun at
all, for it is lost among the stars; and when we discover it we find
that it is only one of the smaller and less conspicuous members of the
sparkling host.
We rapidly approach, and when we have arrived within a distance
comparable with that of its planets, we see that the sun has increased
in apparent magnitude, until now it enormously outshines all the other
stars, and its rays begin to produce the effect of daylight upon the
orbs that they reach. But we are in no danger of mistaking its apparent
superiority to its fellow stars for a real one, because we clearly
perceive that our nearness alone makes it seem so great and
overpowering.
And now we observe that this star that we have drawn near to has
attending it a number of minute satellites, faintly shining specks, that
circle about it as if charmed, like night-wandering insects, by its
splendor. It is manifest to us at the first glance that without the sun
these obedient little planets would not exist; it is his attraction that
binds them together in a system, and his rays that make them visible to
one another in the abyss of space. Although they vary in relative size,
yet we observe a striking similarity among them. They are all globular
bodies, they all turn upon their axes, they all travel about the sun in
the same direction, and their paths all lie very nearly in one plane.
Some of them have one or more moons, or satellites, circling about them
in imitation of their own revolution about the sun. Their family
relationship to one another and to the sun is so evident that it colors
our judgment about them as individuals; and when we happen to find, upon
closer approach, that one of them, the earth, is covered with vegetation
and water and filled with thousands of species of animated creatures, we
are disposed to believe, without further examination, that they are all
alike in this respect, just as they are all alike in receiving light and
heat from the sun.
This preliminary judgment, arising from the evident unity of the
planetary system, can only be varied by an examination of its members in
detail.
One striking fact that commands our attention as soon as we have entered
the narrow precincts of the solar system is the isolation of the sun and
its attendants in space. The solar system occupies a disk-shaped, or
flat circular, expanse, about 5,580,000,000 miles across and relatively
very thin, the sun being in the center. From the sun to the nearest
star, or other sun, the distance is approximately five thousand times
the entire diameter of the solar system. But the vast majority of the
stars are probably a hundred times yet more remote. In other words, if
the Solar system be represented by a circular flower-bed ten feet
across, the nearest star must be placed at a distance of nine and a half
miles, and the great multitude of the stars at a distance of nine
hundred miles!
Or, to put it in another way, let us suppose the sun and his planets to
be represented by a fleet of ships at sea, all included within a space
about half a mile across; then, in order that there might be no shore
relatively nearer than the nearest fixed star is to the sun, we should
have to place our fleet in the middle of the Pacific Ocean, while the
distance of the main shore of the starry universe would be so immense
that the whole surface of the earth would be far too small to hold the
expanse of ocean needed to represent it!
From these general considerations we next proceed to recall some of the
details of the system of worlds amid which we dwell. Besides the earth,
the sun has seven other principal planets in attendance. These eight
planets fall into two classes--the terrestrial planets and the major, or
jovian, planets. The former class comprises Mercury, Venus, the earth,
and Mars, and the latter Jupiter, Saturn, Uranus, and Neptune. I have
named them all in the order of their distance from the sun, beginning
with the nearest.
The terrestrial planets, taking their class name from _terra_, the
earth, are relatively close to the sun and comparatively small. The
major planets--or the jovian planets, if we give them a common title
based upon the name of their chief, Jupiter or Jove--are relatively
distant from the sun and are characterized both by great comparative
size and slight mean density. The terrestrial planets are all included
within a circle, having the sun for a center, about 140,000,000 miles
in radius. The space, or gap, between the outermost of them, Mars, and
the innermost of the jovian planets, Jupiter, is nearly two and a half
times as broad as the entire radius of the circle within which they are
included. And not only is the jovian group of planets widely separated
from the terrestrial group, but the distances between the orbits of its
four members are likewise very great and progressively increasing.
Between Jupiter and Saturn is a gap 400,000,000 miles across, and this
becomes 900,000,000 miles between Saturn and Uranus, and more than
1,000,000,000 miles between Uranus and Neptune. All of these distances
are given in round numbers.
Finally, we come to some very extraordinary worlds--if we can call them
worlds at all--the asteroids. They form a third group, characterized by
the extreme smallness of its individual members, their astonishing
number, and the unusual eccentricities and inclinations of their orbits.
They are situated in the gap between the terrestrial and the jovian
planets, and about 500 of them have been discovered, while there is
reason to think that their real number may be many thousands. The
largest of them is less than 500 miles in diameter, and many of those
recently discovered may be not more than ten or twenty miles in
diameter. What marvelous places of abode such little planets would be if
it were possible to believe them inhabited, we shall see more clearly
when we come to consider them in their turn. But without regard to the
question of habitability, the asteroids will be found extremely
interesting.
In the next chapter we proceed to take up the planets for study as
individuals, beginning with Mercury, the one nearest the sun.