What was the key breakthrough in the interpretation of quasar spectra?

The key leap forward was made by Schmidt in 1963. He understood that few of the emanation lines in the spectra had the example of hydrogen - and that the spectra was hydrogen gas that had been Doppler moved. He understood that these quasars were tremendously redshifted - which was amazing on the grounds that no stargazers figured stars could have immense redshifts like that. This acknowledgment enabled stargazers to better comprehend why quasar spectra looked so unusual.