Astronomy
Spectroscopic Classification Schemes for Quasars and Blazars
Quick fact
Although blazars are a type of quasar, they are often classified separately because their spectra lack the strong emission lines typical of quasars, appearing almost featureless due to overwhelming jet emission from a jet pointing nearly directly at us.
Why this is interesting
You know how every star has its own spectral fingerprint? Imagine pointing a telescope at an object that outshines an entire galaxy—yet its spectrum can look like two completely different things depending on which way you 'look' at it. Why would that be?