Tenerife, Canary Islands, Spain

Tenerife's Teide Observatory at 2,390 metres delivers some of the Northern Hemisphere's clearest astronomical conditions, thanks to strict light-pollution laws and a temperature inversion layer that traps clouds below the summit. The site's altitude reduces atmospheric distortion by 30% compared to sea-level locations like #8 Elqui Valley, and its median seeing of 0.8 arcseconds rivals that of professional mountaintop facilities worldwide. With over 250 clear nights per year and an annual precipitation of just 200 millimetres, Tenerife is drier than the average European stargazing site. The inversion layer ensures that even when coastal towns are overcast, the peak remains above the clouds under a pitch-black sky. Winter night temperatures hover near 0°C, so pack thermal layers, but the reward is unobstructed views from the zenith down to 15 degrees above the horizon.