lenses
because he explore telescopes
Galileo Galilei
Radio telescopes gather data from radio sources and they target the radio frequency part of the electromagnetic spectrum.
Visible light
We can see more stuff.
Optical telescopes are placed high to avoid having to look through the thickest part of the atmosphere. Radio telescopes are place in valleys to avoid the effects of man-made electrical noise in the telescope.
The biggest telescopes on Earth typically operate in the optical and infrared parts of the electromagnetic spectrum. These telescopes are used to study a wide range of celestial objects, from planets and stars to galaxies and quasars.
Researchers use all of these: -- optical telescopes -- radio telescopes -- x-ray telescopes -- infra-red telescopes -- ultraviolet telescopes
refracting
Well, the diameter of the Earth would be a quite irrevocable pragmatic limit.
No they are not bigger then radio telescopes at all.
Radio telescopes collect radio waves. Optical telescopes capture visible light waves.