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Credit & Copyright: Robert Nemiroff
(MTU)
Explanation:
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.)
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NASA Official: Jay Norris. Specific rights apply.
A service of: LHEA at NASA / GSFC
& Michigan Tech. U.
Based on Astronomy Picture
Of the Day
Publications with keywords: black hole
Publications with words: black hole
See also: