Bruce Murray Space Image LibrarySynthetic aperture radar view of the Congo river Synthetic aperture radar view of the Congo river This wide-swath radar image is a mosaic of two images centred over the Congo River, one of the largest rivers in the world flowing 4,374 kilometers from Zambia to the Atlantic Ocean. It was taken on December 23, 2002 from Envisat and is a synthetic aperture radar image, in which brightness corresponds to roughness of the surface. Water appears black in these images. European Space Agency. All rights reserved.