Spain's Dark Skies Threatened by Satellites as Aurora Borealis Becomes Visible

Spain’s prime astronomical sites are facing two contrasting developments. The country’s legislation, the 1988 Ley del Cielo, restricts artificial light to protect sky quality, and locations such as the Roque de los Muchachos observatory on La Palma and the Calar Alto Observatory in Almería continue to offer some of Europe’s clearest night skies. At the same time, the rapid growth of satellite constellations—about 15,000 objects in orbit—poses a new source of light pollution that could compromise astronomical observations.

Recent solar activity has expanded the auroral oval far enough south for the northern lights to be seen from northern Spain when geomagnetic conditions reach a Kp index of 8 or higher. Historical sightings date back to 1938, with renewed visibility recorded in May 2024 and projected for future solar maxima. Optimal viewing spots include high‑altitude, low‑light‑pollution sites such as Calar Alto and the Serra del Montsec in Lleida, turning these areas into emerging destinations for astrotourism.