Synchronous orbit

The synchronous orbit is a Orbite on which a Natural satellite will put as much time to achieve a Révolution around a Astre than this star will take some to even carry out a turn on him.

In the particular case of the Ground, one speaks about a geosynchronous orbit.

So moreover the Slope and the orbital Excentricité of this orbit is null, then the satellite will appear motionless seen central star - in the contrary case it will appear to describe a Analemme.

Note : not to confuse the synchronous orbit with the synchronous Rotation in which the satellite puts as much time to carry out a full rotation on itself than to achieve a revolution around the central star.

Implication in Planetology

The fact for a Natural satellite of orbiting in on this side of the synchronous orbit (i.e. to achieve a revolution around a Planet in less time than does not put this one to carry out a full rotation on itself) generally involves fatal consequences.

Indeed, the Forces of tide exerted by planet slowly slow down the satellite, which loses little by little altitude and will end up being crushed one day on planet, unless it is not dislocated before by reaching the Limite of Rock and forms possibly new a planetary Anneau.

Several moons of our Solar system are in this critical situation: it is in particular the case of Phobos (satellite of Mars), Cordélia and Ophélie (Natural satellite of Uranus) and of Naïade, Thalassa and Despina (Natural satellite of Neptune).

Synchronous orbit for the principal bodies of the solar system

(1) Altitude measured from surface

See too

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