QSO - Quasi Stellar Object, also Quasar: QSOs are star like objects with very large redshifts (i.e. the light they emit is strongly displaced toward the red end of the spectrum). Although their exact nature is controversial, they are commonly considered to be extremely distant, unusually bright nuclei of galaxies. If so, then the light we see from them would have been emitted when the universe was a fraction of its present age.