Quasars are most likely the centers of active galaxies, and may produce their energy from the huge black holes found in the center of the galaxies in which the quasars are located.
Quasars drown out the light from all the other stars in the same galaxy because they are so bright.
Quasars look like stars, but are much farther away than stars in our galaxy, and they are much brighter. Even though they are very far away, the visible light and the strong radio radiation astronomers see shows that quasars must be very bright. In 1963 astronomers figured out that these massive objects were about one billion to ten billion light years away. The energy from a quasar takes billions of years to get to the Earth's atmosphere. In 1987, British and American astronomers discovered an object that may be 12 billion light years away.