Physics · Ch 6 — Gravitation
Geo-stationary and Polar Satellite
Geo-stationary and Polar Satellite
Satellites orbiting at different heights have different orbital periods (from Kepler's third law, Section 6.4.1) -- so by choosing the right height, a satellite's period can be made to match any value we want, including exactly one day.
Geostationary satellites. Setting the orbital period to hours () in and solving for gives a height of about above the equator. A satellite placed there, in the plane of the equator, orbits at exactly the same rate the Earth spins, so it appears to hang motionless over one fixed spot on Earth as seen from the ground -- hence "geostationary." India's INSAT group of satellites, used for telecommunication, are geostationary satellites of exactly this kind. …
What this figure shows. Earth is shown at the centre with two very different orbital paths drawn around it. One is a wide circular orbit in the plane of the equator, far from the surface, labelled the geostationary orbit, carrying a geostationary satellite. The other is a much lower, narrower circular orbit that passes directly over the North and South poles, labelled the polar orbit, carrying a polar orbiting satellite -- visually contrasting their very differ …
What this figure shows. The Earth is shown as a sphere with a single narrow curved strip running from pole to pole highlighted on its surface, representing the ground area a polar satellite scans during one revolution; because the Earth keeps rotating underneath the satellite's fixed orbital plane, the next revolution covers a different adjacent strip, so that a full day's worth of orbits eventually images the entire …