The city lights of Spain and Portugal define the Iberian Peninsula in this photograph taken from the International Space Station (ISS) on 4 December 2011. Several large metropolitan areas are visible, marked by their relatively large and brightly lit areas, such as the capital cities of Madrid, Spain - located near the center of the peninsula's interior - and Lisbon, Portugal - located along the southwestern coastline. The ancient city of Seville, visible at image right to the north of the approximately 14 km (9 mi)-wide Strait of Gibraltar, is one of the largest cities in Spain. The view is looking outwards from the ISS towards the east.
The network of smaller cities and towns in the interior and along the coastline attest to the areal extent of human presence on the Iberian landscape. Blurring of the city lights is caused by thin cloud cover (image left and center), while the cloud tops are dimly illuminated by moonlight. Though obscured, the lights of France are visible near the horizon line at image upper left, while the lights of northern Africa are more clearly discernable at image right. The gold to green line of airglow, caused by excitation of upper atmosphere gas molecules by ultraviolet radiation, parallels the horizon line (or Earth limb). Image courtesy of NASA.