CHAPTER XIII.

THE MOON AS A WORLD: DAY AND NIGHT UPON ITS SURFACE. 155 Existence of Habitants on other Planets—Interest of the Question—Conditions of Life—Absence of these from Moon—No Air or Water and intense Heat and Cold—Possible Existence of Protogerms of Life—A Day on the Moon imagined—Instructiveness of the Realization—Length of Lunar Day—No Dawn or Twilight—Sudden Appearance of Light—Slowness of Sun in Rising—No Atmospheric Tints—Blackness of Sky and Visibility of Stars and fainter Luminosities at Noon-day—Appearance of the Earth as a Stationary Moon—Its Phases—Eclipse of Sun by Earth—Attendant Phenomena—Lunar Landscape—Height essential to secure a Point of View—Sunrise on a Crater—Desolation of Scene—No Vestige of Life—Colour of Volcanic Products—No Atmospheric Perspective—Blackness of Shadows—Impressions on other Senses than Sight—Heat of Sun untempered—Intense Cold in Shade—Dead Silence—No Medium to conduct Sound—Lunar Afternoon and Sunset—Night—The Earth a Moon—Its Size, Rotation, and Features—Shadow of Moon upon it—Lunar Night-Sky—Constellations—Comets and Planets—No Visible Meteors—Bombardment by Dark Meteoric Masses—Lunar Landscape by Night—Intensity of Cold