Question

Why are optical telescope located in unihabitated place on mountain

Answer 1

We use space telescopes, like Hubble, because you gain a lot by getting rid of the atmosphere. For groundbased telescopes, the light from astronomical objects that they receive has to go through all of the atmosphere, which causes attenuation and distortion. Therefore, the less atmosphere and the more stable the atmosphere, the better. For some types of telescopes, humidity is also a problem, so the dryer the atmosphere the better. The sites in the world that fit these criteria are few and generally remote: the top of volcano Mauna Kea in Hawaii, the Atacama desert in Northern Chile (and other sites in altitude in Chile), Antarctica, the desert in Arizona, California and New Mexico (though this last places suffer more and more from light pollution as cities get bigger and bigger).