Spectroscopy
When the media covers astronomy, they nearly always show pretty pictures. This gives a biassed view of what astronomers actually do: well over 70% of all observations are not pictures - they are spectra.
Spectra are the most vital tool of astronomy - without them we’d be lost. However, they are slightly more complicated to understand than pictures (and nothing like as pretty), so the media ignores them.
Light is made up of waves of entwined electricity and magnetism. This applies to all types of light, including radio waves and X-rays. The general term for these waves is “Electromagnetic Waves”.
These waves always travel at the same speed: 300,000 kilometres per second.