When we look up at the stars our eyes see the visible light that’s travelled billions of miles to get here. And when early astronomers first turned their telescopes to the sky, the visible light is what they could see. But, as technology improved, astronomers starting looking at the sky using other forms of light energy, like electromagnetic radiation, gravitational waves, and now even neutrinos and cosmic rays. Each is created by different astrophysical processes, and so provide different kinds