Any light that enters a black hole can't escape from it - that's the definition of a black hole - that escape velocity is greater than the speed of light.
So - light from behind the black hole would be absorbed by it. So it should seem black.
But - it is likely to be surrounded by matter continually falling into it, in an accretion disk - and that can get very bright.
And then gravitational lensing lets you see the far side of the accretion disk, which is actually behind the black hole, warped above it.
This is what the black hole of Interestellar would look like, to naked eye taking account of colour shifting.
Though the movie makers thought that would confuse the audience so simplified it to the more symmetrical:
See
The Truth Behind Interstellar's "Scientifically Accurate" Black Hole
So - light from behind the black hole would be absorbed by it. So it should seem black.
But - it is likely to be surrounded by matter continually falling into it, in an accretion disk - and that can get very bright.
And then gravitational lensing lets you see the far side of the accretion disk, which is actually behind the black hole, warped above it.
This is what the black hole of Interestellar would look like, to naked eye taking account of colour shifting.
Though the movie makers thought that would confuse the audience so simplified it to the more symmetrical:
The Truth Behind Interstellar's "Scientifically Accurate" Black Hole
About the Author
Robert Walker
Writer of articles on Mars and Space issues - Software Developer of Tune Smithy, Bounce Metronome etc.Studied at Wolfson College, Oxford
Lives in Isle of Mull
4.8m answer views110.3k this month
Top Writer2017, 2016, and 2015
Published WriterHuffPost, Slate, and 4 moreHuffPost, Slate, Forbes, Newsweek, Business Insider, and Science 2.0