Chapter II: 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