Dwarfing the Nile, a river of dust flowed out of the deserts of northern Egypt on May 19, 2007.

As the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite passed overhead at 12:05 p.m. local time in Cairo, the sensor captured this image of the dust spreading northward over the Mediterranean Sea from the sandy deserts that span the country. At the margins of the plume, ribbons and ripples of dust are translucent, allowing glimpses of the desert and water beneath, but in the center, the cloud is opaque.

The part of north-central Egypt hidden by the dust plume is the Qattara Depression, the country's lowest point. Dipping down to 133 meters below sea level (436 feet), the depression is home to sandy deserts and dry lake beds that occasionally flood. The sand and fine, lake bed sediments are easily lofted into the air by strong winds that scour the area in late winter and early spring.

In the eastern part of the image at right, dull green vegetation marks the Nile River. Tan-colored spots in the fan-shaped delta identify cities and towns. The Nile Valley and Delta occupy only a small fraction of the country's total land area, yet they support almost the entire population.

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--NASA's Earth Observatory and SPACE.com Staff

Credit: Jeff Schmaltz, MODIS Rapid Response Team, Goddard Space Flight Center