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 […] The post Circling the Black Hole at the Photon Sphere appeared first on NASA Science .
Picture a spacecraft orbiting a black hole, where light can dance endlessly around its edge due to the immense gravitational pull. Known as the photon sphere, this region is the dividing line between the black hole and the surrounding sky. As the spacecraft circles the black hole, the sky seems to move in bizarre ways. An Einstein ring, formed by background stars, appears as an invisible line above the photon sphere.
Stars on the far side of the black hole from the spacecraft approach this line, become magnified, and move rapidly across the sky. However, viewing only one magnified star at a time, due to its 180-degree positioning around the black hole. The motion of the spacecraft can cause a star image near the Einstein ring to become extremely bright and vanish, while the other bright image of the same star reappears above the ring and then fades.
Just remember, you are not at the event horizon, which still lies below. Journeys into the event horizon would transform the sky into a single dot opposite the black hole, a concept that my computer programs cannot accurately depict nor can they venture that far at present. The mysteries of what lies inside a black hole remain unanswered.
For now, you may take a virtual trip to a neutron star or explore more in the American Journal of Physics on this subject.
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- Looking Up at the Photon Sphere science.nasa.gov
