What do you mean, key sets of spectral lines?

In practice, it can be measured as a Doppler effect of the spectral lines.

The light was growing brighter at the same time the spectral lines were shifting toward the red.

He established empirical rules for the analysis of spectral lines, which remain associated with his name.

Matter that is further out will produce a narrow, sharper spectral line.

The first term is due to the emission in every single spectral line.

In order to understand spectral lines, color has to be understood.

Since each set of spectral lines was unique, scientists could also be able to use this in a technique called red shift.

A shift in its spectral line, and he'd caught it.

Each substance will have its own unique pattern of spectral lines.