Looking Up at the Photon Sphere

The first frame is dark as you peer into the black hole itself. You begin to look up and stars come back into view. Now the stars are more blue than ever before as starlight that has fallen into the black hole to reach you has become more energetic. You may notice many dim stars just above the blackness - these are stars that are greatly de-magnified by the enormous gravity. You may also notice that some stars that you see in front of you - you expected to see behind you. Starlight from these stars has been bent around the far side of the black hole.

No starlight can reach you from below - it could not escape the black hole's enormous gravity. In other words, all light that crosses the photon sphere going in can never go outward from the black hole.

Next: Circling the Black Hole at the Photon Sphere.


Play the movie segment: Looking Up at the Photon Sphere.
Play the next movie segment: Circling the Black Hole at the Photon Sphere.
Go to the hypertext describing the next movie segment: Circling the Black Hole at the Photon Sphere.
Peruse the American Journal of Physics Article on this subject.

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