IN view of the considerable attention given to the secondary spectrum of hydrogen in recent investigations, it may be worth announcing that this spectrum has been extended photographically so far ...

The light from each star is directed through a prism to produce a spectrum. Each of the spectra has a set of absorption lines created by the presence of hydrogen in the stars' atmospheres.

When a gas is very hot, it doesn’t emit all wavelengths of light. Hot gases don’t produce a continuous emission spectrum. Black hydrogen absorption lines are at the same wavelength as the ...