Atacama Desert, Chile
Virtually cloudless, and with an altitude of 8,200 feet and many areas receiving less than an inch of rain annually, this barren, northern Chilean desert is simply one of the highest, driest regions on the planet. (Humidity amplifies horizon lighting and makes celestial objects look blurry.) The optimally clear skies have attracted big bucks from astronomical agencies worldwide; two of the three next-generation, monster ground telescopes are slated to begin operations here in the 2020s. In the meantime, visitors are welcome to camp out under the piercingly bright stars.