The large white feature at the bottom of the view is a dry lake known locally as Etosha Pan. Its white color is the result of a salt residue left behind from the evaporation of water that annually gathers in this semiarid region. The straight line across the top of this scene is the international boundary between Namibia (bottom) and Angola (top). A marked contrast in land-use practices on either side of this border accounts for the difference in the color. In Namibia, a greater amount of livestock grazing has occurred, resulting in less vegetative cover (and higher reflectivity) than in neighboring Angola. A greater population density in northern Namibia may contribute to this trend.
While many international borders lie along waterways (such as seas, lakes, and rivers) and other natural barriers (such as mountains), they are sometimes oriented parallel to lines of latitude or longitude. The straight border in this scene is a remnant from colonial occupation in southwest Africa and was only established in the late nineteenth century. It trends east-west along a line of constant latitude and divides the traditional lands of the Ovambo people. Although such stark contrasts in land use are generally uncommon, they are also apparent at the Egypt-Israel border and the western U.S.-Canada border.
June 1985, image STS-51G-46-78.