Reflectory and Refractory
Researchers use all of these: -- optical telescopes -- radio telescopes -- x-ray telescopes -- infra-red telescopes -- ultraviolet telescopes
Optical telescopes are of two types: refractive and reflective. The refractive telescopes have chromatic aberration (huh? different colors are focused in different plains -- huh?). This is less of a problem with reflective telescopes.
Refracting telescopes and reflecting telescopes are commonly used to observe stars in visible light. These telescopes utilize lenses or mirrors to gather and focus light, allowing astronomers to view stars with clarity and detail.
Reflecting telescopes do this. There are many different kinds of reflectors.
Y
They study all kinds of things or look through telescopes and look at the sky to see what's happening
refracting
No they are not bigger then radio telescopes at all.
Radio telescopes collect radio waves. Optical telescopes capture visible light waves.
Ground-based telescopes, and space telescopes. Or: refracting telescopes (main collector is a lens), and reflecting telescopes (main collector is a mirror). Or: Home telescopes (small ones), and professional ones (larger and more expensive).
At a store for telescopes!
All space telescopes are unmanned - unless you want to count the small telescopes on the Shuttle or IIS as space telescopes.