A Black Hole...
You can't see a black hole itself. Einstein's equations
show that where mass is concentrated to an extreme, space
closes in upon itself until not even light can escape the
gravitational pull. But you can see matter glowing with
heat as it falls in. This picture taken by the Hubble Space
Telescope shows a whirlpool of hot gas orbiting an astonishing
object in the middle of the distant galaxy M87.