12. Nodes are the opposite points of a planet where its orbit cuts the ecliptic or the earth’s orbit.
13. Apogee is the point of a planet’s orbit farthest from the earth. Perigee is the nearest point.
14. The terms Culmination, Conjunction, and Opposition require no special explanation. But planets are in conjunction with each other when in the same sign and degree. A planet with the sun between it and the earth is in conjunction with the sun. With the earth between it and the sun it is in opposition.
15. Latitude and longitude upon a celestial globe are known respectively as “Declination” and “Right Ascension.”
16. The Radius Vector is a line drawn from a planet to the sun, wherever the planet may be (see fig. 497).
CHAPTER XXXIV.
ANGLES AND MEASUREMENT OF ANGLES.
THE QUADRANT—TRANSIT INSTRUMENT—CLOCKS—STELLAR TIME—SOLAR TIME—“MEAN” TIME.
We must say a few words respecting the various instruments and aids to astronomical observation before proceeding, for astronomy requires very accurate calculations; and though we do not propose to be very scientific in our descriptions, some little idea of the manner in which observations may be made is necessary. The first thing to see about is the Angle.