Chapter I
Reading edition
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