Black holes in galaxies

Not all stars shine, the universe is home to many dark stars. Black holes are very massive objects whose gravitational field is so intense that it prevents any form of matter or radiation from escaping. Black holes are described by the general theory of relativity. When the core of the dead star is too massive to become a neutron star, it contracts inexorably until it forms this mysterious astronomical object, the black hole. Stellar black holes range in mass from a few solar masses to billions of solar masses.