How are radio telescopes different from optical telescopes?

Radio telescopes and optical telescopes are both essential tools for astronomy, but they differ fundamentally in the type of radiation they detect and their physical construction.12

• Detection Range: Optical telescopes are designed to observe visible light within or near the range detectable by the human eye. In contrast, radio telescopes are instrumented to detect cosmic emitters of radio waves, allowing astronomers to study the universe across a different portion of the electromagnetic spectrum.2
• Physical Design: Because cosmic radio sources are extremely weak, radio telescopes are typically much larger than optical telescopes, often featuring massive parabolic antennas or "dishes" that can span hundreds of metres. While optical telescopes focus light to form images, radio telescopes use a radio receiver to amplify and detect incoming signals.3
• Environmental Sensitivity: Radio telescopes are highly susceptible to terrestrial radio interference, requiring them to be protected from man-made emissions. Some are even located in designated "quiet zones" to ensure signal clarity.34