Venus by Radar

On the Cover: The thick, sulfuric-acid clouds of Venus hide its surface from conventional imaging techniques. Scientists have turned to cloud-piercing radar to "see" through to the surface. Soviet <i>Venera</i> and U.S. <i>Pioneer</i> orbiters returned radar data that scientists have compiled into images and maps of the planet's surface. Earth-based radar systems, such as the Arecibo Radio Telescope in Puerto Rico, can also be used to study Venus. Here is an Arecibo image of a region southeast of Lakshmi Planum in the northern hemisphere. Purples and blues represent smooth areas, while greens and yellows are rougher areas.