Radius of a photon's circular orbit around a mass

birulami
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What is the radius of a photon's circular orbit around a mass M? My guess would be the Scharzschild radius. Is that true?
 
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For Kerr, the Wikipedia article only mentions the two (co-rotating and counter-rotating) circular equatorial photon orbits. Does Kerr have closed non-equatorial photon orbits? (If so, they would presumably be noncircular.)
 
Wow, that's very interesting! Thanks
 
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