VenusΓÇÖs thick atmosphere obscures its surface in visible light. To Earth-basedΓÇöeven to space- basedΓÇöoptical telescopes the planet presents a bright but largely featureless face. Before the advent of unmanned space flights, clever astronomers, knowing that radio waves can penetrate even thick cloud cover, bounced radar signals off the planet, inferring surface features from the returning signals. This technique gave tantalizing glimpses of the surface, but it took spacecraft like the Venus Pioneer and the Magellan expeditions to provide the radar imaging necessary to create detailed false color maps of the planet, like that seen here (from Magellan data).
