Circling the Black Hole at the Photon Sphere

You currently sit at the black hole's photon sphere, where light can travel endlessly in a circle due to the star's great gravitational pull. The apparent position of the photon sphere is always easy to spot - it is the apparent dividing line between black hole and sky.

As you circle the black hole the sky appears to move in strange ways. Here an Einstein ring for background stars can be seen as an invisible line above the photon sphere horizon. Stars approaching the exact other side of the black hole from you appear to approach this line, are greatly magnified, and move with high angular speeds. As one background star image is greatly magnified, so is another 180 degrees around the black hole - but with your current point of view you can see only one at a time. Your spaceship's motion can cause a star image below this Einstein ring to become very bright and shoot out of view - while a moment later the other bright image of this same star zooms into view above the Einstein ring and fades.

You are not at the event horizon, which is still below you. Were you to travel to the event horizon the sky would appear to scrunch up into a little dot opposite the black hole. My computer programs cannot yet track you that far with much accuracy, and so I cannot take you there today. Nobody really knows what it looks like inside a black hole, on the other side of the event horizon.

Next: Take a trip to a neutron star.

Replay the movie segment: Circling the Black Hole at the Photon Sphere.
Peruse the American Journal of Physics Article on this subject.

Back to Virtual Trips to Black Holes and Neutron Stars Page