So rapid, indeed, has been the progress of astronomy in very recent years that the present is especially favorable for setting forth its salient features; and this book is an attempt to present the wide range of astronomy in readable fashion, as if a story with a definite plot, from its origin with the shepherds of ancient Chaldea down to present-day ascertainment of the actual scale of the universe, and definite measures of the huge volume of supersolar giants among the stars.

David Todd

Amherst College Observatory
November, 1921

CONTENTS

CHAPTERPAGE
[I]Astronomy a Living Science9
[II]The First Astronomers19
[III]Pyramid, Tomb, and Temple23
[IV]Origin of Greek Astronomy27
[V]Measuring the Earth—Eratosthenes30
[VI]Ptolemy and His Great Book33
[VII]Astronomy of the Middle Ages37
[VIII]Copernicus and the New Era42
[IX]Tycho, the Great Observer45
[X]Kepler, the Great Calculator49
[XI]Galileo, the Great Experimenter53
[XII]After the Great Masters57
[XIII]Newton and Motion62
[XIV]Newton and Gravitation66
[XV]After Newton73
[XVI]Halley and His Comet83
[XVII]Bradley and Aberration90
[XVIII]The Telescope93
[XIX]Reflectors—Mirror Telescopes102
[XX]The Story of the Spectroscope111
[XXI]The Story of Astronomical Photography125
[XXII]Mountain Observatories139
[XXIII]The Program of a Great Observatory152
[XXIV]Our Solar System162
[XXV]The Sun and Observing It165
[XXVI]Sun Spots and Prominences174
[XXVII]The Inner Planets189
[XXVIII]The Moon and Her Surface193
[XXIX]Eclipses of the Moon206
[XXX]Total Eclipses of the Sun209
[XXXI]The Solar Corona 219
[XXXII]The Ruddy Planet227
[XXXIII]The Canals of Mars235
[XXXIV]Life in Other Worlds242
[XXXV]The Little Planets254
[XXXVI]The Giant Planet260
[XXXVII]The Ringed Planet264
[XXXVIII]The Farthest Planets267
[XXXIX]The Trans-Neptunian Planet270
[XL]Comets—the Hairy Stars273
[XLI]Where Do Comets Come From?279
[XLII]Meteors and Shooting Stars283
[XLIII]Meteorites290
[XLIV]The Universe of Stars294
[XLV]Star Charts and Catalogues300
[XLVI]The Sun's Motion Toward Lyra304
[XLVII]Stars and Their Spectral Type307
[XLVIII]Star Distances311
[XLIX]The Nearest Stars319
[L]Actual Dimensions of the Stars321
[LI]The Variable Stars324
[LII]The Novæ, or New Stars331
[LIII]The Double Stars334
[LIV]The Star Clusters336
[LV]Moving Clusters341
[LVI]The Two Star Streams345
[LVII]The Galaxy or Milky Way350
[LVIII]Star Clouds and Nebulæ357
[LIX]The Spiral Nebulæ361
[LX]Cosmogony366
[LXI]Cosmogony in Transition380

LIST OF ILLUSTRATIONS

[Active Prominence of the Sun, 140,000 Miles High]Frontispiece
FACING PAGE
[Nicholas Copernicus]64
[Galileo Galilei]64
[Johann Kepler]65
[Sir Isaac Newton]65
[The Hundred-Inch Reflecting Telescope at Mount Wilson]96
[The Forty-Inch Refracting Telescope, Yerkes Observatory]96
[150-Foot Tower, Mount Wilson, a Diagram of Tower and Pit]97
[150-Foot Tower—Exterior View]97
[View Looking Down into the Pit Beneath 150-Foot Tower]97
[Mount Wilson Solar Observatory—the 100-Foot Dome]128
[Mount Chimborazo, the Best Site in the World for an Observatory]128
[Lick Observatory, Mount Hamilton, California]129
[Photographing with the 40-inch Refractor]129
[Great Sunspot Group of August 8, 1917]160
[Calcium Flocculi on the Sun]161
[Eclipse of the Moon, with the Lunar Surface Visible]161
[Moon's Surface in the Region of Copernicus]192
[South Central Portion of the Moon, at Last Quarter] 193
[Corona of the Sun During an Eclipse]224
[Venus, in the Crescent Phase]225
[Mars, Showing Bright Polar Cap]225
[Jupiter, the Giant Planet]256
[Neptune and Its Satellites]256
[Saturn, with Edge of Rings only in View]257
[Saturn, with Rings Displayed to Fullest Extent]257
[Two Views of Halley's Comet]288
[Swift's Comet, which Showed Remarkable Transformations]288
[Meteor Trail in Field with Fine Nebulæ]289
[Ring Nebula in Lyra]320
[Dumb-bell Nebula]321
[Star Clouds and Black Holes in Sagittarius]352
[Great Nebula in Andromeda]353