This image of the northern portion of the Nile River was captured by the Multi-angle Imaging Spectroradiometer's (MISR's) nadir camera on January 30, 2001. Against the barren desert of northeastern Africa, the fertile valley of the Nile River runs northward through Egypt. The city of Cairo can be seen as a gray smudge right where the river widens into its broad fan-shaped delta. Other cities are dotted across the green landscape, giving it a speckled appearance. Where the Nile empties into the Mediterranean Sea (top) the waters are swirling with color, likely a mixture of sediment, organic matter, and possibly marine plant life. Farther west, the bright blue color of the water is likely less-organically rich sediment, perhaps sand.
Excerpted from: Sahara Desert Was Once Lush and Populated