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