#photon sphere

[thepastisalreadywritten]

Anatomy of a Black Hole

[viablackholes-blog]

Travel Inside A Black Hole (pt 2): The Photon Sphere.

  As you approach the photon sphere light won’t get sucked into the black hole, but it also won’t leave it, in fact at this point, light photons actually orbit around the black hole. If you theoretically could control yourself and stop at this point and look to your side you would be able to see the back of your own head. This is because light reflecting on the back of your head would travel all the way around back to where your eyes are, making it possible to see the back of you.

[alxndrasplace]

(NASA)  Circling a Black Hole at its Photon Sphere Image Credit & Copyright: Robert Nemiroff (MTU)

What would it look like to go right up to a black hole? One particularly interesting place near a black hole is its photon sphere, where photons can orbit in circles, a sphere 50 percent further out than the event horizon. Were you to look out from the photon sphere of a black hole, half of the sky would appear completely black, half of the sky would appear unusually bright, and the back of your head would appear across the middle. The above computer-animated video depicts this view from the photon sphere. The reason that the lower region, as shown, appears black is because all light paths from this dark region comes up from the black hole -- which classically emits no light. The upper half of the sky now appears unusually bright, blueshifted, and shows increasingly many complete sky images increasingly close to the dark-light divide across the middle. That dark-light divide is the photon sphere -- your location -- and since photons can do circles there, light from the back of your head can circle the black hole and come to your eye. No place on the sky is hidden from you -- stars that would normally pass behind the black hole now appear to zip quickly around an Einstein ring, a ring that appears above as a horizontal line about a quarter of the way down from the video top. The above video is part of a sequence of videos visually exploring the space near a black hole's event horizon. (Disclosure: Video creator Robert Nemiroff is an editor for APOD.)

[lsebk1]

Band: Psychotria

Song: Photon Sphere

Genre: Progressive Metal

[wigmund]

From Astronomy Picture Of The Day; July 2, 2013:

Circling a Black Hole at its Photon Sphere  Robert Nemiroff (MTU)

What would it look like to go right up to a black hole? One particularly interesting place near a black hole is its photon sphere, where photons can orbit in circles, a sphere 50 percent further out than the event horizon. Were you to look out from the photon sphere of a black hole, half of the sky would appear completely black, half of the sky would appear unusually bright, and the back of your head would appear across the middle. The above computer-animated video depicts this view from the photon sphere. The reason that the lower region, as shown, appears black is because all light paths from this dark region comes up from the black hole -- which classically emits no light. The upper half of the sky now appears unusually bright, blueshifted, and shows increasingly many complete sky images increasingly close to the dark-light divide across the middle. That dark-light divide is the photon sphere -- your location -- and since photons can do circles there, light from the back of your head can circle the black hole and come to your eye. No place on the sky is hidden from you -- stars that would normally pass behind the black hole now appear to zip quickly around an Einstein ring, a ring that appears above as a horizontal line about a quarter of the way down from the video top. The above video is part of a sequence of videos visually exploring the space near a black hole's event horizon. (Disclosure: Video creator Robert Nemiroff is an editor for APOD.)