The Nile River near the Fourth Cataract
The upper photograph was taken by astronauts aboard the Space Shuttle, while the lower image of the same area is a specially-processed Shuttle Imaging Radar (SIR-C/X-SAR) image. The radar image shows a previously unknown paleochannel lying north of the Nile that cannot be seen on the photograph. These observations indicate that the course of the Nile along the Fourth Cataract has recently shifted to the south due to relative uplift of adjacent regions of the Nubian Swell (details in Stern & Abdelsalam paper in Science).