Matter orbiting the black hole at the center of a galaxy sometimes falls into the hole. Scientists recently gave an explanation for this saying that magnetic fields involved cause some matter to fall. Otherwise, of course, it would orbit the black hole forever, just as the earth orbits the sun forever (as long as the sun does not explode!).

 

When matter falls into the black hole, powerful light comes out. This is the brightest light in the universe. This light is so bright that it can shine from one end of the universe to the other.

 

Here is an artist's conception of a quasar. See

http://chandra.harvard.edu/press/04_releases/press_010504.html

 

This is from the Chandra X-ray Observatory, a telescope in orbit. A large blue star is near the black hole, and parts of the star are falling into the hole. As stuff falls into the hole, the jets come out. These jets are the quasar lights.