Geostationary orbit
= Geostationary orbit
{wiki}
A <geostationary orbit> is a prograde equatorial <circular Kepler orbit> whose <orbital period> equals one <sidereal day>, so its satellite remains above a fixed location on <Earth>'s equator. It is the terrestrial case of a <planet-stationary orbit>. Its radius follows from <Newton's law of universal gravitation> and circular <acceleration>: $r=(GM_ET^2/(4\pi^2))^{1/3}$, approximately $42164\ \mathrm{km}$ from <Earth>'s centre. Its altitude above the surface is smaller by <Earth>'s radius.