The redshifts of the underlying galaxies match the redshifts of the quasars embedded in their centers, thereby proving that quasars obey the Hubble law and are at the great distances implied by their redshifts. The first quasars discovered looked like stars but had strong radio emission.

The quasar spectra obtained so far show redshifts ranging from 15% to more than 96% the speed of light. Observations with the Hubble Space Telescope show that quasars lie at the centers of galaxies and that both spirals and ellipticals can harbor quasars.

quasar — an object of very high redshift that looks like a star but is extragalactic and highly luminous; also called a quasi-stellar object, or QSO. active galaxies — galaxies that house active galactic nuclei. Hubble law and — at the great distances implied by their redshifts. active galactic nuclei (AGN) — galaxies that are almost as luminous as quasars and share many of their properties, although to a less spectacular degree; abnormal amounts of energy are produced in their centers.