With the aid of the Nautical Almanac and the charts the amateur will find no difficulty, after a little practise, in keeping track of any of the planets.

In the back part of the Nautical Almanac will be found two pages headed “Phenomena:  Planetary Configurations.”  With the aid of these the student can determine the position of the planets with respect to the sun and the moon, and with respect to one another.  The meaning of the various symbols used in the tables will be found explained on a page facing the calendar at the beginning of the book.  From these tables, among other things, the times of greatest elongation from the sun of the planets Mercury and Venus can be found.

It may be added that only bright stars, and stars easily seen, are included in the charts, and there will be no danger of mistaking any of these stars for a planet, if the observer first carefully learns to recognize their configurations.  Neither Mars, Jupiter, nor Saturn ever appears as faint as any of the stars, except those of the first magnitude, included in the charts.  Uranus and Neptune being invisible to the naked eye—­Uranus can occasionally be just glimpsed by a keen eye—­are too faint to be found without the aid of more effective appliances.

INDEX

Agassiz, Alexander, on deep-sea animals, 63.

Asteroids, the, 16, 129.
  brightness of, 130.
  imaginary adventures on, 146.
  life on, 144.
  number of, known, 129.
  orbits of, 132.
  origin of, 138, 143.
  size of, 129.

Aristarchus, lunar crater, 226.

Atmosphere, importance of, 20.

Bailey, Solon I., on oppositions of Eros, 134.

Barnard, E.E., discovers fifth satellite of Jupiter, 181.
  measures asteroids, 129.
  on Saturn’s rings, 205.

Belopolski, on rotation of Venus, 79.

Ceres, an asteroid, 129, 130.

Clefts in the moon, 226.

Copernicus, lunar crater, 223, 242.

Darwin, George H., on Jupiter and Saturn, 206.
  on origin of moon, 235.
  theory of tidal friction, 32.

Davy, Sir Humphry, on Saturn, 190.

Dawes sees canals on Mars, 93.

Deimos, satellite of Mars, 125.

Denning, W.F., description of Jupiter, 175.

De Vico on rotation of Venus, 76.

Dewar, James, discovers free hydrogen in air, 232.

De Witt discovers Eros, 133.

Dick, Thomas, on Saturn, 201.

Douglass, A.E., sees Mars’s canals, 92.
  sees clouds in Mars, 119.

Doppler’s principle, 79, 200.

Earth and moon’s orbit, 217.
  birth of moon from, 236.
  change of distance from sun, 27.
  less advanced than Mars, 89.
  older than Venus, 58.
  seen from Mercury, 41.
  seen from Venus, 69-71, 75.
  seen from moon, 214.

Earth, similarity to Venus, 46.
  supposed signals to and from Mars, 110.