black hole

A black hole is a single point in space where pressure and density are infinite. It is the remains of a massive star (a star at least two or three times the mass of our sun) that has burned out its nuclear fuel and collapsed under tremendous gravitational force. Any object even light that gets too close to a black hole gets pulled in, stretched to infinity, and remains forever trapped. While black holes are impossible to see, they may account for 90 percent of the content of the universe.

The concept of black holes was introduced by English geologist (a scientist specializing in the origin, history, and structure of the Earth) John Michell and French astronomer (a scientist specializing in the study of outer space) Pierre-Simon Laplace in the late eighteenth century. Scientists first called black holes "gravitationally collapsed objects." Russian scientists later re-named them "collapsars."