Solution:

Astronomers make use of all possible information coming from astronomical objects, even information we cannot see. For example, all objects in the universe emit radio waves naturally. We call these cosmic radio waves. Observations of cosmic radio waves has revealed an “invisible” universe whose existence was undreamed of a century ago. Those waves to which our eyes respond are called “light”. Our bodies sense infra-red waves as radiant heat. At long wavelengths, cosmic radio waves tend to come from violent processes in the universe such as exploding stars or galaxies.