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 ...

The findings could shed important new light on how the outer ... "We've strongly suspected that hydrogen sulphide gas was influencing the millimetre spectrum of Uranus for some time, but we ...