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Radio astronomy uses radio waves to study regions of space.
Single-dish radio telescopes produce blurry images. When an optical image of an object is formed by reflecting light rays from a mirror onto a focus, quite sharp images of extended objects can be made. The blurring stems from a basic principle that affects all types of telescopes. Light waves have wavelengths of less than one millionth of a metre, and so collecting mirrors are large enough compared to a wavelegth of light that they can resolve the details of objects observed. However, radio waves have wavelengths of roughly one tenth of a metre and so even large radio telescope dishes produce blurry images.