I can't say I understand how one can get accurate images a bizzillion miles away using RF. RF just fans out like light?
The National Radio Astronomy Observatory was a customer of mine for 20 years. One of my favorite and least productive customer visits, lots of cool stuff, not Much $. Usually some University funded program and they typically wanted EVERYTHING for free.
Radio astronomy is part of astronomy in general. People tend to think of optical or visual light astronomy, Galileos spy glass and the like. It is. But there are other kinds of astronomy.
Generally speaking, all types of astronomy receive electromagnetic energy to see the universe. Humans see light, which is also electromagnetic energy, photons, just like radio energy, just a different frequency. The least energetic EM waves and lowest frequency, or longest wavelength would be radio and i guess the most energetic shortest wavelength gamma rays? Visible light is there in the middle.
Radio astronomy receives a narrow section of EM energy emitted from various objects. These are radio wavelengths which approach infrared. All objects emit all kinds of energies, radio astronomy looks at the radio emissions to determine the make up of objects.
One really cool thing they do, thanks to the power of the computer I hate to admit. They put receivers, dishes, all over the place and using boo koo processing powers to somehow stitch together the various antenna signals and generate an image. You basically build a synthetic aperture by distributing the antennas. You fool mother nature. In medicine it's called tomography.
Other folks do similar things in defense, like radar cross sections.
