An astronaut aboard the International Space Station (ISS) focused a camera lens on a brilliant spot in Iran: the sun reflecting off Darodzan Lake. This waterbody in the desert, surrounded by the Zagros Mountains, is impounded behind a dam wall just upstream of the town of Darodzan.

Winds ruffle the water surface so that the reflection pattern is quite varied; it changes by the minute when viewed from the ISS. At the moment this image was taken, the sunglint effect was strongest near the dam wall. (The science of sunglint is explained here.) Other bright streaks in the middle of the lake show the counter-clockwise circulation of water. Yet more streaks show the direction of the wind (from the west).

Agricultural fields in deserts are closely tied to sources of water. In this region, fields are clustered along the river that feeds the lake. The river enters Darodzan Lake at a small delta (image left). Other fields are clustered downstream of the dam wall, next to the town. The dam wall itself was built at a narrow gap in steep ridges.