A composite satellite image of the geography of Africa, the Earth's second-largest continent, and its adjacent islands. Separated from Europe by the Mediterranean Sea and from much of Asia by the Red Sea, Africa is joined to Asia at its northeast extremity by the Isthmus of Suez. For geopolitical purposes, the Sinai Peninsula – east of the Suez Canal – is often considered part of Africa, although geographically it belongs in Asia. Africa can be divided into a number of geographic zones: The Atlas Mountains in the north, the Sahara, the coastal plains, and the inner plateaus.Photo: NASA