The emission lines in quasar spectra were difficult to identify at first because:
A)emission lines of such intensity were not expected from astronomical sources.
B)no one expected far-ultraviolet spectral lines to be shifted to visible wavelengths.
C)they were very faint and could not be measured accurately.
D)they arise from elements that do not exist on Earth.

Question

Quizplus · Accepted Answer

Quasar spectra showed emission lines that were unexpected, as they were far-ultraviolet spectral lines shifted to visible wavelengths (known as redshift). This phenomenon was not initially understood, making it difficult to identify the emission lines in the spectra.

The Emission Lines in Quasar Spectra Were Difficult to Identify