The geostationary ring is a volume segment around the geostationary orbit defined by variations in altitude and declination that can occur for uncontrolled objects left in the geostationary orbit.
The geostationary orbit is subject to orbit perturbations caused by anomalies in the gravitational field of the Earth, by the gravitational effects of Sun and Moon, and by solar radiation pressure.
A precessional motion of the orbit plane is caused by the oblatedness of the Earth (
On the other hand, solar radiation pressure induces an eccentricity that leads to a variation of the orbit radius by ± 75 kilometers in some cases.
This leads to the definition of the geostationary ring as being a segment of space around the geostationary orbit that ranges from 75 km below GEO to 75 km above GEO and from -15 degrees to 15 degrees declination.