Effect of Earth's Oblateness on the Period of a Satellite

Abstract

The effect of the earth's oblateness on the period of the lat i tudinal mot ion of a satellite in a near-circular orbit is investigated, and it is shown that in addition to the usual dependence on alt i tude the period depends as well on the incl ination of the orbit to the equator. For orbits in the neighborhood of the equator, the period is less than for a n orbit at the same he ight around a spherical earth. The period increases wi th orbit incl inat ion, and for polar orbits the period is greater than for an orbit at the same he ight over a spherical earth. For a satell ite at a he ight of 300 miles the difference in periods between polar and nearequatorial orbits is 12 sec.