As before, from this orientation, the black hole’s enormous gravity bends light to make two discernible images of the constellation Orion. You now descend to the photon sphere. A photon sphere is a location where gravity is so strong that light can travel in circles. Photons orbit the black hole at the distance of the photon sphere. A photon could leave the back of your head, go once around the black hole, and be seen by your eye – you can see the back of your head.
At the photon sphere, no light emitted outside can reach you from below – you look into the vast emptiness of the black hole. The sky you once knew is now behind you, compacted to occupy only half its original area.
Next: Looking up at the photon sphere.
Replay the movie segment: Approaching the Photon Sphere.
Play the next movie segment: Looking Up at the Photon Sphere.
Go to the hypertext describing the next movie segment: Looking Up at the Photon Sphere.
Peruse the American Journal of Physics Article on this subject.
