Black Hole Photon Sphere

In this simulation, your spacecraft orbits at the photon sphere of the black hole. This is defined to be the radius at which light could be put into a circular orbit around the black hole. Thus, at the photon sphere you should (with a large enough telescope) be able to see the back of your head, since light reflected from the back of your head can orbit completely around the black hole and strike your eyes from the front.

The photon sphere is not the same as the event horizon, which lies below it. For a spherical black hole the photon sphere lies at 1.5 times the radius of the event horizon. Usage: Click "Play" to begin and "Stop" to halt. "Step" moves forward one step and "Back" moves backwards one step. "Home" returns to the beginning from any point.