The subtropical Canary Islands off Africa’s west coast are pictured in this Envisat image.
The Canary Islands’ favourable climate and beaches attract over 12 million visitors per year. Perhaps some beach-goers were on those aircraft that left the multiple contrails over the dark blue water to the north.
Because the archipelago is far away from areas with high light pollution like big cities, it is an ideal location for astronomical observations. (Full article)