Stargazing on Teide: how dark Tenerife's sky really is, and where to stand
Tenerife is the easiest high-altitude sky in Europe to get to: two international airports and a paved road up to the Teide cable car’s base station at 2,356 m. The catch is in the photometry. The professional observatory on the Izaña ridge measures its moonless zenith at 21.20 magnitudes per square arcsecond, half a magnitude brighter than La Palma’s Roque de los Muchachos, about 144 km to the west-northwest. Below I go through where that extra light comes from, which caldera viewpoints to use, what the guided tours cost, and what a winter trip to 28° north shows you that Cyprus can’t. ...