[amsat-bb] Re: sirius orbit name?

melachri@speakeasy.net melachri at speakeasy.net
Thu Feb 21 14:10:25 PST 2008

> Strictly speaking, you can't have a truly geosynchronous orbit that's  
> elliptical (it must be circular). It must also have an inclination of  
> zero.

Rick -

You are confusing geosynchronous with geostationary. Geosynchronous simply means that the orbit period is equal to one sidereal day, so it's "synchronized" with the earth's rotation. As a result, it will always trace the same pattern on the earth's surface. The orbit shape can be just about anything as long as the period is 23 hours, 56 minutes, 4.1 seconds.

A special case of geosynchronous orbits is the geostationary orbit, which as you point out, is circular with zero inclination. As its name indicates, it appears stationary to an earth observer, so the "pattern" on the earth's surface is simply the single sub-satellite point.


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