Why are many observatories located on mountaintops?
Almost all of the world’s finest ground-based observatories are located on mountains — for a variety of reasons. First and foremost, starlight appears less distorted in the thin atmosphere on mountaintops. (Space-based telescopes such as Hubble and the Gamma-Ray Observatory circumvent the disturbing effects of the atmosphere by flying love it.) Mountaintops also have unobstructed views of the horizon in all directions. Lastly, most cities and towns — with their accompanying light pollution — are situated in valleys and plains, so remote mountaintops are among the last places on Earth to find the dark skies so sought after by astronomers.
