The top image is shown in the visible spectrum, then (below) the 21 cm (1.42 GHz) radio spectrum of the Hydrogen atom emission. Hydrogen, H, is THE most abundant element in the universe.
Notice the (21 cm) radio waves ‘see’ right through the dark ‘dust’ lanes that block the visible light. This is another advantage of radio over optical, as it can penetrate celestial structures otherwise obscured by dirt & dust.
RADIO ‘IMAGE’ DATA