[Footnote 21:  In our latitudes, planets are never seen in the northern quarter of the sky.  When on the meridian, they are always somewhere between the zenith and the southern horizon.]

[Illustration:  CHART NO. 1.—­FROM RIGHT ASCENSION 0 HOURS TO 4 HOURS; DECLINATION 30 deg.  NORTH TO 10 deg.  SOUTH.]

Having learned to recognize the constellations and their chief stars on sight, one other step, an extremely easy one, remains to be taken before beginning your search for the planets—­buy the American Ephemeris and Nautical Almanac for the current year.  It is published under the direction of the United States Naval Observatory at Washington, and can be purchased for one dollar.

This book, which may appear to you rather bulky and formidable for an almanac, contains hundreds of pages and scores of tables to which you need pay no attention.  They are for navigators and astronomers, and are much more innocent than they look.  The plain citizen, seeking only an introduction to the planets, can return their stare and pass by, without feeling in the least humiliated.

[Illustration:  CHART NO. 2.—­FROM RIGHT ASCENSION 4 HOURS TO 8 HOURS; DECLINATION 30 deg.  NORTH TO 10 deg.  SOUTH.]

In the front part of the book, after the long calendar, and the tables relating to the sun and the moon, will be found about thirty pages of tables headed, in large black letters, with the names of the planets—­Mercury, Venus, Mars, Jupiter, Saturn, etc.  Two months are represented on each page, and opposite the number of each successive day of the month the position of the planet is given in hours, minutes, and seconds of right ascension, and degrees, minutes, and seconds of north and south declination, the sign + meaning north, and the sign — south.  Do not trouble yourself with the seconds in either column, and take the minutes only when the number is large.  The hours of right ascension and the degrees of declination are the main things to be noticed.

Right ascension, by the way, expresses the distance of a celestial body, such as a star or a planet, east of the vernal equinox, or the first point of Aries, which is an arbitrary point on the equator of the heavens, which serves, like the meridian of Greenwich on the earth, as a starting-place for reckoning longitude.  The entire circuit of the heavens along the equator is divided into twenty-four hours of right ascension, each hour covering 15 deg. of space.  If a planet then is in right ascension (usually printed for short R.A.) 0 h. 0 m. 0 s., it is on the meridian of the vernal equinox, or the celestial Greenwich; if it is in R.A. 1 h., it will be found 15 deg. east of the vernal equinox, and so on.

[Illustration:  CHART NO. 3.—­FROM RIGHT ASCENSION 8 HOURS TO 12 HOURS; DECLINATION 30 deg.  NORTH TO 10 deg.  SOUTH.]

Declination (printed D. or Dec.) expresses the distance of a celestial body north or south of the equator of the heavens.