Oddly enough, visible light is the smallest band of radiation. To our eyes, visible light seems like the entire universe. Yet there is much more out there. The Electromagnetic Spectrum Different types of objects in the universe emit different types of radiation. Our Sun is a rather obvious source of visible light.
Some objects emit only radio waves or only X-rays.
This is why it is important to study the Universe with various kinds of telescopes. We don't want to miss anything. We see the lovely spiral shape of the galaxy and the position of all the stars within it. The X-ray image, at first glance, seems like a mess. What you see there are not individual stars but rather the extremely hot gas in between the stars and forming a halo around the galaxies.