Answer: Astronomers use the entire electromagnetic spectrum to observe a variety of things. Radio waves and microwaves – the longest wavelengths and lowest energies of light – are used to peer inside dense interstellar clouds and track the motion of cold, dark gas
The electromagnetic spectrum is used for identifying what type a wave is. For example, a wave with a very low frequency would be a radio wave, and a wave with a very high wavelength would be a gamma wave.
