This shift was explained by the Doppler Effect. Stellar objects, including the quasar, move away from one another as the universe expands. This results in emitted radiation appearing to have longer wavelengths than what would be called normal. These redshifts can help determine how far form Earth quasars are. These distances, calculated from Hubble's law of galactic expansion, show that most quasars are not part of the Milky Way Galaxy, often billions of light years away.
Astronomers believe black holes hold the answer.
This gaseous matter falls into the black hole, forming an accretion disc. It is this activity that produces the intense radiation characteristic of quasars. These unique bodies are rather miniscule in size compared to other heavenly objects, yet they certainly leave their mark in the depths of space. The quasar averages around one or two light years in size. This quasar physical dimension data came about from observations of varying light outputs.