Because quasars look much like stars in photographs, they are sometimes called quasi-stellar objects. Most quasars are about the size of the solar system. But they can be a trillion times brighter than the sun.
Quasars are among the most distant objects yet detected in the universe.
Astronomers determine how distant a quasar is by measuring its red shift. Red shift is a shift in the wavelength of light given off by an astronomical object toward the longer, or red, wavelengths of the object's spectrum. It indicates an object is moving away from the earth. The more distant the object is, the larger is its red shift. All quasars have large red shifts.