# What is the maximum inclination a geosynchronous orbit can have?

A geosynchronous orbit is one where a satellite's orbital period (more or less) matches a planet's rotation period. However, this is distinct from a geostationary orbit, where a satellite must remain over the same spot on the Earth. In an inclined geosynchronous orbit, a satellite would trace out an analemma over the course of a sidereal day. Such an orbit would also slowly decay, requiring adjustment over time.

Since you can have a geosynchronous orbit that is inclined, what is the maximum inclination you can have before it is no longer considered "geosynchronous"?

Asking because I found an interesting paper which considers the possibility of detecting aliens through geosynchronous satellites in orbit around their planets.

• 180°, same as any other orbit. Commented Feb 28, 2018 at 21:24
• @notovny Orbital inclinations go from -90° to 90°, not to 180°. Commented Feb 28, 2018 at 21:25
• @Phileros Orbital inclinations of >90° are how retrograde orbits are traditionally expressed. I've never seen a negative orbital inclination in a list of orbital parameters, myself. Commented Feb 28, 2018 at 21:47
• It would be important for a geosynchronous orbit, since it would correspond to the latitude of the spot it is geosynchronous over. Commented Feb 28, 2018 at 21:48
• @Phiteros as the inclination is the angle between the orbit angular momentum vector and the Z axis of the reference frame, the domain is in fact 0-180, not -90-90. Commented Mar 1, 2018 at 1:50