Geosynchronous satellites are used for many telecommunication and broadcast purposes. Such satellites appear to be stationary as viewed from the ground, and are able to provide coverage over large areas. Around the time of equinoxes each year the Sun passes close to a given geostationary satellite at some time of the day.

The time of year at which interference takes place depends on the latitude of the observing station. The duration of the interference depends on the receiving antenna beamwidth. The time of day at which the interference will occur depends upon the relative position of the satellite. A satellite in the western sky will be subject to interference in the afternoon; but in the morning if in the eastern sky.