_HOW TO FIND THE PLANETS_ 256 It is easy to make acquaintance with the planets and to follow them among the stars--The first step a knowledge of the constellations--How this is to be acquired--How to use the Nautical Almanac in connection with the charts in this book--The visibility of Mercury and Venus--The oppositions of Mars, Jupiter, and Saturn INDEX 277 LIST OF ILLUSTRATIONS PAGE Chart of Mars _Frontispiece_ Diagram showing causes of day and night on portions of Mercury 35 Regions of day and night on Mercury 38 Venus's atmosphere seen as a ring of light 56 View of Jupiter _facing_ 168 Three views of Saturn _facing_ 186 Diagram showing the moon's path through space 217 The lunar Alps, Apennines, and Caucasus _facing_ 222 The moon at first and last quarter _facing_ 226 Phases and rotation of the moon 250 Charts showing the zodiacal constellations: 1.

From right ascension 0 hours to 4 hours 259 2.

" " 4 " " 8 " 261 3.

" " 8 " " 2 " 263 4.

" " 12 " " 16 " 265 5.