In article ,
Roy Smith wrote:
I know what a geo synchronous orbit is, but what's the "figure eight"
part all about?

A satellite in geosynchronous orbit (i.e. one that completes an orbit in
exactly one Earth rotation) only appears to be stationary if the orbit is
circular and inclined exactly along the equator.

If it isn't, the satellite appears to move eastward as it travels faster
around perigee, and westward as it slows around apogee. Differences in
inclination account for apparent north and south movement.

The combination of the two sets of apparent movements describes a figure
of eight path above an observer on the ground.

Stationary satellites tend to acquire such orbits when they are left to
their own devices, e.g when propellant runs low, or are put in such
orbits deliberately, allowing them to continue to be used for odd jobs
after being replaced.

-- don