Question

Imagine that you want to build a radio telescope and an optical telescope and that you want them to both have the same angular resolution, assume that both telescopes can reach the diffraction limit. Which telescope will have to have a larger diameter? Explain your reasoning.

Answer 1

The radio telescope will have to have a larger diameter than the optical telescope in order to achieve the same angular resolution. This is because radio waves have a longer wavelength than optical waves, and the angular resolution of a telescope is inversely proportional to the wavelength of the radiation it is observing. Since the radio waves have a longer wavelength, the telescope observing them will need a larger diameter in order to achieve the same level of resolution as a telescope observing optical waves. Additionally, the diffraction limit for radio telescopes is greater than for optical telescopes, so the radio telescope will need to be larger to reach the diffraction limit.