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The Question

(Submitted February 06, 2000)

Hi, I am interested in black holes and have taken a Astronomy 100 college class. My question is: if you were to take a picture of a star-field and a black hole were to come between you and the center of the same star-field, and it is relatively near to you, how would the appearance of the star-field change? Thanks!

The Answer

The black hole would look black, since any stars behind it would be shadowed by it. Around the black hole, outside its event horizon, though, you would see a rim of light from stars behind it. Some of the light from these stars that started out at an angle from you will be bent by the strong gravitational field and would reach your eye. In a very real sense, the black hole is a "gravitational lens."

We hope this helps!

Enectali Figueroa and John Cannizzo
for "Ask a NASA Scientist"

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