XXXIV. LIFE IN OTHER WORLDS 242 XXXV. THE LITTLE PLANETS 254 XXXVI. THE GIANT PLANET 260 XXXVII. THE RINGED PLANET 264 XXXVIII. THE FARTHEST PLANETS 267 XXXIX. THE TRANS-NEPTUNIAN PLANET 270 XL. COMETS--THE HAIRY STARS 273 XLI. WHERE DO COMETS COME FROM? 279 XLII. METEORS AND SHOOTING STARS 283 XLIII. METEORITES 290 XLIV. THE UNIVERSE OF STARS 294 XLV. STAR CHARTS AND CATALOGUES 300 XLVI. THE SUN'S MOTION TOWARD LYRA 304 XLVII. STARS AND THEIR SPECTRAL TYPE 307 XLVIII. STAR DISTANCES 311 XLIX. THE NEAREST STARS 319 L. ACTUAL DIMENSIONS OF THE STARS 321 LI. THE VARIABLE STARS 324 LII. THE NOVÆ, OR NEW STARS 331 LIII. THE DOUBLE STARS 334 LIV. THE STAR CLUSTERS 336 LV. MOVING CLUSTERS 341 LVI. THE TWO STAR STREAMS 345 LVII. THE GALAXY OR MILKY WAY 350 LVIII. STAR CLOUDS AND NEBULÆ 357 LIX. THE SPIRAL NEBULÆ 361 LX. COSMOGONY 366 LXI. COSMOGONY IN TRANSITION 380 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