Black Hole (2009)
A black hole is a collapsed star, the remains of a once massive star whose core ran
out of nuclear fuel and imploded. All of the star's mass now occupies a single point
in spacetime called a singularity. Black holes cannot be seen by definition, because
they emit no light. But they can be seen indirectly, as in this image, if they are
surrounded by a ring of stellar debris, an accretion disc.
