Sun and planets motion navigation


Sun and planets motion navigationThe center of the sun oscillates around a small orbit whose diameter is only about 280 miles. This is an insignificant distance when compared with the distances of the planets from the sun, and for practical purposes, the sun may be considered as being at rest with regard to the other members of the solar system.

The planets move about the sun in accordance with the following laws, known as Kepler's Laws:

(1) The orbit of every planet is an ellipse, having the sun at one of its foci.
(2) The radius vector of a planet sweeps over equal areas in equal times.
(3) The squares of the times of revolution about the sun of any two planets are proportional to the cubes of their mean distances from the sun.

The above laws are not of great use in navigation but the reader should retain from them the facts that:

(1) the orbits of the planets are not circular, but elliptical; and
(2) the motions of the planets in their orbits, while following regular laws, are not uniform, and that the nearer a planet is to the sun, the shorter is its period of revolution and hence the greater is its angular speed.

The planes of the orbits of all of the planets nearly coincide with the plane of the earth's orbit, i.e., with the plane of the ecliptic. The direction of revolution about the sun of all the planets is in the same direction as the earth's revolution, i.e., eastward.