Earth's darkest, clearest skies, by most estimates, can be found in the remote high deserts of northern Chile—which is why astronomers have for decades heavily invested in building telescopes there. The latest, greatest observatory for the region is the European Southern Observatory's (ESO) $1.5-billion Extremely Large Telescope (ELT)—which will, upon completion, be the world's largest optical telescope.
This gargantuan observatory will be a workhorse for breakthrough investigations of potentially habitable exoplanets, dark energy and an assortment of other enticing topics at astronomy's frontiers. Unless, as our top story explains, a proposed multibillion-dollar renewable-energy megaproject is built too close for comfort. Light pollution and other disturbances from the sprawling complex could encroach upon the delicate celestial observations of the ELT and other nearby telescopes, ESO officials say, effectively stifling what could otherwise be a new golden age of ground-based astronomy.
The matter remains unsettled, and in dispute, with a planned period of public and stakeholder feedback on the renewable-energy project now underway. But you can bet the global astronomy community will be watching it closely—and Scientific American will be, too. Stay tuned for more updates, and in the meantime, keep looking up! —Lee Billings
