THE distribution of the lines in the spectra of the elements is by no means so irregular as it might seem at first sight. Since Lecoq de Boisbaudran, in 1869, discovered the general plan in the ...

Studying the line spectra produced by hot gases and absorbed by cooler gases allows us to identify the elements in stars. When a gas is very hot, it doesn’t emit all wavelengths of light.

The Chi-squared goodness of fit statistical method, which compares either concentrations or spectra lines directly, is used to match an unknown spectrum to possible library candidates. The matching ...