Voici pourquoi:

* Thickly Clouded: Venus has a dense, highly reflective atmosphere of carbon dioxide, making it perpetually shrouded in thick clouds. This makes it difficult to see its surface from space using visible light.

* Radar Mapping: Radar can penetrate these clouds and map the surface by bouncing radio waves off the terrain.

* Varied Topography: La cartographie radar a révélé que la surface de Vénus est étonnamment diversifiée, avec de vastes plaines, des hautes terres imposantes et de nombreuses structures volcaniques, y compris des volcans de bouclier, des flux de lave et même des calderas.

Let me know if you have any other planetary mysteries!