I remember, as a kid, reading about Cygnus X-1, which was discovered in 1964 and is the first black hole ever discovered. What made Cygnus X-1 so cool to my fevered childhood imagination is that it orbits a companion star, at a distance only about 20% of the distance from the Earth to the Sun. That means that stellar material is constantly being torn from the star and drawn towards the black hole. The thought of that both fascinated and terrified me then, and frankly, still does a little bit now. Continued...