As I write, engineers and scientists are firing up a very important radio telescope. Used in conjunction with ground-based instruments, it will make it possible to emulate a radio telescope bigger than our planet.
Radio waves are just like light waves, but much bigger.
For a given ability to resolve detail, radio telescopes have to be far larger than optical ones. Radio waves coming to us from space show us things we would not find out about in any other way. They can be used to study quasars and the bright nuclei of active galaxies. However, these objects are very distant, and appear too small in the sky to map with any radio telescope. The quest to look inside quasars and active galactic nuclei led an informal race among the world's astronomers to come up with some way of emulating the performance of radio telescopes too big to build.