... Sun . ... ESA?s Venus Express mission returned this image of sulphuric acid clouds over the southern hemisphere of Venus (Image credit: ESA) . ... Venus was long thought of as Earthт??s т??sister planetт?? ... Galileo was first to see that Venus shows phases just as our Moon does and he cleverly used this fact (along with the planetт??s proximity to the Sun) to demonstrate that Venus orbited the Sun and not the Earth. ... As its surface is hidden by clouds, Venus was regarded as a mysterious planet....