Radio astronomy uses radio waves to study regions of space. Radio waves are a form of electromagnetic radiation - like visible light waves only with much longer wavelengths. Visible light waves are oscillating electromagnetic signals with wavelengths of less than one millionth of a metre, whereas radio waves have wavelengths in the range of a few millimetres to several metres. Radio telescopes gather and concentrate the radio waves from an astronomical source. The signal received …showed first 75 words of 336 total…

…showed last 75 words of 336 total…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. A single radio dish would have to be many kilometres across to achieve a sharp image at radio wavelengths and such telescopes have been too difficult to build.