text: why is a radio telescope not capaple of attaining the same resolutions as an optical telescope of the same? size? the resolution of an imaging system is limited by diffraction. the image of a point source, such as a star, has an angular size that is proportional to the wavelength of the light or radio waves, divided by aperture. light waves are around 500 nanometers (500 x 10^-9 meters), while radio astronomy is typically done at wavelengths of a few centimeters (n x 10^-2 meters). so a radio telescope would have to be around 100,000 times the size of an optical telescope to achieve the same resolution.   rather than build impossibly huge radio dishes, radio astronomy uses synthetic aperture techniques, combining the signals from widely separated dishes to get the resolution of a single dish the diameter of the separation.