Why must geostationary orbits be equatorial?

Only an equatorial orbit keeps the satellite stationary relative to the surface. An inclined orbit traces a figure-eight.

Geosynchronous vs geostationary?

Geosynchronous means the period matches rotation. Geostationary adds zero inclination and zero eccentricity.

In principle yes. Fast-spinning planets have lower altitudes; slow rotators have much higher ones.

Compute the geostationary orbit altitude and speed for any planet given its mass and rotation period.

Planet Mass

Rotation Period

Planet Radius

Orbit Radius

42,163.1 km

Altitude Above Surface35,792.1 km

Orbital Speed3,074.59 m/s

Orbit Radius vs Rotation Period

A geostationary orbit has a period equal to the planet's rotation, so the satellite appears fixed above one equatorial spot.

r = (G M T² / 4π²)^(1/3)

For Earth: T = 86 164 s (sidereal day), giving r ≈ 42 164 km, altitude ≈ 35 786 km.

Find Earth's geostationary orbit.