Terkezi Oasis, Chad, Africa

A series of rocky outcroppings are a prominent feature of this Sahara Desert landscape near the Terkezi Oasis in the country of Chad. The rocks are dark blue and the desert sand is pale orange in this image.

This image was taken on 10/22/2000.

Volga River Delta, Kazakhstan (Eurasia)

Where the Volga River flows into the Caspian Sea, it creates an extensive delta. The Volga Delta has more than 500 channels, and includes the most productive fishing grounds in Eurasia.

This image was taken on 8/29/1999.

Karman Vortices, Selkirk Island, off South America

Each of these swirling clouds is caused by a weather condition known as a Karman vortex. These vortices appeared over Alexander Selkirk Island in the southern Pacific Ocean. Rising sharply from the surrounding waters, the island's highest point is nearly a 1.6 kilometer (1 mile) above sea level. As wind-driven clouds run into this obstacle, they flow around it to form these large, spinning eddies.

This image was taken on 9/15/1999.